STRIBILD

Integrase Strand Transfer Inhibitor (INSTI) and Nucleoside and Nucleotide Reverse Transcriptase Inhibitor (NRTI) Combinations

Oral Administration

Administer tablet with food.

Severe

bone fractures / Delayed / 3.9-3.9
suicidal ideation / Delayed / 0.3-0.3
lactic acidosis / Delayed / Incidence not known
Fanconi syndrome / Delayed / Incidence not known
renal failure (unspecified) / Delayed / Incidence not known
rhabdomyolysis / Delayed / Incidence not known
hepatitis B exacerbation / Delayed / Incidence not known
hepatic decompensation / Delayed / Incidence not known
hepatic failure / Delayed / Incidence not known
pancreatitis / Delayed / Incidence not known
angioedema / Rapid / Incidence not known

Moderate

proteinuria / Delayed / 44.0-52.0
hematuria / Delayed / 4.0-4.0
elevated hepatic enzymes / Delayed / 3.0-3.0
hyperamylasemia / Delayed / 3.0-3.0
steatosis / Delayed / Incidence not known
hepatomegaly / Delayed / Incidence not known
hypophosphatemia / Delayed / Incidence not known
bone pain / Delayed / Incidence not known
myasthenia / Delayed / Incidence not known
osteopenia / Delayed / Incidence not known
osteomalacia / Delayed / Incidence not known
myopathy / Delayed / Incidence not known
hyperbilirubinemia / Delayed / Incidence not known
peripheral neuropathy / Delayed / Incidence not known
depression / Delayed / Incidence not known
hyperglycemia / Delayed / Incidence not known
hyperlipidemia / Delayed / Incidence not known
hypertriglyceridemia / Delayed / Incidence not known
hypercholesterolemia / Delayed / Incidence not known
hypokalemia / Delayed / Incidence not known
hypoglycemia / Early / Incidence not known
glycosuria / Early / Incidence not known
dyspnea / Early / Incidence not known
neutropenia / Delayed / Incidence not known

Mild

nausea / Early / 4.0-16.0
diarrhea / Early / 12.0-12.0
headache / Early / 2.0-7.0
fatigue / Early / 1.0-4.0
rash / Early / 4.0-4.0
dizziness / Early / 3.0-3.0
insomnia / Early / 3.0-3.0
flatulence / Early / 2.0-2.0
asthenia / Delayed / Incidence not known
arthralgia / Delayed / Incidence not known
back pain / Delayed / Incidence not known
myalgia / Early / Incidence not known
vomiting / Early / Incidence not known
abdominal pain / Early / Incidence not known
weight gain / Delayed / Incidence not known
dyspepsia / Early / Incidence not known
anxiety / Delayed / Incidence not known
paresthesias / Delayed / Incidence not known
skin hyperpigmentation / Delayed / Incidence not known
maculopapular rash / Early / Incidence not known
skin discoloration / Delayed / Incidence not known
pruritus / Rapid / Incidence not known
urticaria / Rapid / Incidence not known
infection / Delayed / Incidence not known
sinusitis / Delayed / Incidence not known
fever / Early / Incidence not known
rhinitis / Early / Incidence not known
cough / Delayed / Incidence not known
pharyngitis / Delayed / Incidence not known

Hepatitis B and HIV coinfection, hepatitis B exacerbation

Elvitegravir; cobicistat; emtricitabine; tenofovir disoproxil fumarate is not indicated for the treatment of chronic hepatitis B virus (HBV) infection, and safety and efficacy have not been established in patients with hepatitis B and HIV coinfection. However, both tenofovir disoproxil fumarate and emtricitabine are used for the treatment of HBV infection. Perform HBV screening in any patient who presents with HIV infection to assure appropriate treatment. Patients who are coinfected with HIV and HBV should be started on a fully suppressive antiretroviral (ARV) regimen with activity against both viruses (regardless of CD4 counts and HBV DNA concentrations). HIV treatment guidelines recommend these patients receive an ARV regimen that contains a dual NRTI backbone of tenofovir alafenamide or tenofovir disoproxil fumarate with either emtricitabine or lamivudine. If tenofovir cannot be used, entecavir should be used in combination with a fully suppressive ARV regimen (note: entecavir should not be considered part of the ARV regimen). Avoid using single-drug therapy to treat HBV (i.e., lamivudine, emtricitabine, tenofovir, or entecavir as the only active agent) as this may result in HIV resistant strains. Further, HBV treatment regimens that include adefovir or telbivudine should also be avoided, as these regimens are associated with a higher incidence of toxicities and increased rates of HBV treatment failure. Most coinfected patients should continue treatment indefinitely with the goal of maximal HIV suppression and prevention of HBV relapse. Patients with coexisting HBV and HIV infection who discontinue tenofovir or emtricitabine may experience a severe acute hepatitis B exacerbation with some cases resulting in hepatic decompensation and hepatic failure. Therefore, close monitoring of transaminase concentrations every 6 weeks for the first 3 months, and every 3 to 6 months thereafter is recommended in coinfected patients who discontinue NRTI therapy. If appropriate, resumption of anti-hepatitis B treatment may be required. For patients who refuse a fully suppressive ARV regimen, but still require treatment for HBV, consider 48 weeks of peginterferon alfa; do not administer HIV-active medications in the absence of a fully suppressive ARV regimen. Instruct patients to avoid consuming alcohol, and offer vaccinations against hepatitis A and hepatitis B as appropriate. [34362] [46638] [51664]

STRIBILD

Rx

Fixed-dose combination tablet containing elvitegravir, an HIV integrase strand transfer inhibitor; cobicistat, a pharmacokinetic enhancer; emtricitabine, a nucleoside reverse transcriptase inhibitor or NRTI; and tenofovir DF, an acyclic nucleotide reverse transcriptase inhibitor
Used for the treatment of HIV-1 infection in patients who are least 12 years of age and weigh at least 35 kg
Carries a Black Box Warning for acute exacerbations of hepatitis

For the treatment of human immunodeficiency virus (HIV) infection in antiretroviral-naive and certain treatment-experienced patients.
NOTE: Use in treatment-experienced patients is limited to those who have been virologically-suppressed (i.e., HIV RNA less than 50 copies/mL) on a stable antiretroviral regimen for at least 6 months, have no history of treatment failure, and who are without known substitutions associated with resistance to any of the individual components. For patients meeting these criteria, elvitegravir; cobicistat; emtricitabine; tenofovir disoproxil fumarate may replace the current antiretroviral therapy.
NOTE: Test all patients for hepatitis B virus (HBV) infection prior to initiating therapy. Elvitegravir; cobicistat; emtricitabine; tenofovir disoproxil fumarate is not indicated for the treatment of chronic hepatitis B virus (HBV) infection, and the safety and efficacy of treatment have not been established in patients co-infected with HBV and HIV.[51664] Oral dosage Adults

One tablet (elvitegravir 150 mg; cobicistat 150 mg; emtricitabine 200 mg; tenofovir disoproxil fumarate 300 mg) PO once daily. This dosage constitutes a complete treatment regimen; use with other antiretroviral medications is not recommended.

Children and Adolescents 12 to 17 years weighing 35 kg or more

One tablet (elvitegravir 150 mg; cobicistat 150 mg; emtricitabine 200 mg; tenofovir disoproxil fumarate 300 mg) PO once daily. This dosage constitutes a complete treatment regimen; use with other antiretroviral medications is not recommended.

For human immunodeficiency virus (HIV) prophylaxis† after occupational exposure to HIV. Oral dosage Adults

One tablet (elvitegravir 150 mg; cobicistat 150 mg; emtricitabine 200 mg; tenofovir disoproxil fumarate 300 mg) PO once daily for 4 weeks as alternative therapy. This dosage constitutes a complete regimen; use with other antiretroviral medications is not recommended. Although animal studies suggest PEP started more than 72 hours following exposure is substantially less effective, the interval after which no benefit is derived for humans is undefined. Decisions regarding initiation of prophylaxis beyond 72 hours after exposure should be made on a case-by-case basis with the realization of diminished efficacy when the timing is prolonged.

†Indicates off-label use

Hepatic Impairment

Dosage adjustments are not required for mild to moderate hepatic impairment (Child-Pugh Class A and B). Due to lack of data, use is not recommended in patients with severe hepatic impairment (Child-Pugh Class C).

Renal Impairment

CrCl 70 mL/minute or more: No dosage adjustment needed.
CrCl less than 70 mL/minute: Do not initiate treatment.
CrCl less than 50 mL/minute: Discontinue if CrCl falls below 50 mL/minute during treatment, as the required dose adjustments for emtricitabine and tenofovir disoproxil fumarate cannot be accomplished with this fixed-dose regimen.

Abacavir; Dolutegravir; Lamivudine: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine. (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp.
Abacavir; Lamivudine, 3TC: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine.
Abacavir; Lamivudine, 3TC; Zidovudine, ZDV: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine.
Abemaciclib: (Major) If coadministration with cobicistat is necessary, reduce the dose of abemaciclib to 100 mg PO twice daily in patients on either of the recommended starting doses of either 200 mg or 150 mg twice daily. In patients who have had already had a dose reduction to 100 mg twice daily due to adverse reactions, further reduce the dose of abemaciclib to 50 mg PO twice daily. Discontinue abemaciclib for patients unable to tolerate 50 mg twice daily. If cobicistat is discontinued, increase the dose of abemaciclib to the original dose after 3 to 5 half-lives of cobicistat. Abemaciclib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the relative potency adjusted unbound AUC of abemaciclib plus its active metabolites (M2, M18, and M20) by 2.5-fold in cancer patients.
Abrocitinib: (Moderate) Coadministration of tenofovir disoproxil fumarate with abrocitinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and abrocitinib is a P-gp inhibitor.
Acalabrutinib: (Major) Avoid the concomitant use of acalabrutinib and cobicistat; significantly increased acalabrutinib exposure may occur. Acalabrutinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In healthy subjects, the Cmax and AUC values of acalabrutinib were increased by 3.9-fold and 5.1-fold, respectively, when acalabrutinib was coadministered with another strong inhibitor for 5 days. (Moderate) Coadministration of acalabrutinib and tenofovir disoproxil fumerate may increase may increase the absorption and plasma concentration of tenofovir disoproxil fumerate. Monitor patients for tenofovir-related adverse reactions and discontinue use in patients who experience an adverse reaction. Acalabrutinib is an inhibitor of the breast cancer resistance protein (BCRP) transporter in vitro; it may inhibit intestinal BCRP. Tenofovir disoproxil fumerate is a BCRP substrate.
Acetaminophen; Aspirin, ASA; Caffeine: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Acetaminophen; Aspirin: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Acetaminophen; Aspirin; Diphenhydramine: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus. (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Caution is warranted when elvitegravir is administered with diphenhydramine as there is a potential for decreased diphenhydramine concentrations. Diphenhydramine is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Concomitant use of dihydrocodeine with cobicistat may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
Acetaminophen; Chlorpheniramine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Acetaminophen; Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Acetaminophen; Dextromethorphan: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Acetaminophen; Diphenhydramine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Caution is warranted when elvitegravir is administered with diphenhydramine as there is a potential for decreased diphenhydramine concentrations. Diphenhydramine is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Acetaminophen; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
Acetaminophen; Ibuprofen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Acetaminophen; Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone.
Acyclovir: (Moderate) Monitor for acyclovir or emtricitabine-related adverse events during concomitant use. Concomitant use may increase acyclovir or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as acyclovir and emtricitabine, may increase the risk of adverse reactions. (Moderate) Monitor for changes in serum creatinine and phosphorus if tenofovir disoproxil fumarate is administered in combination with nephrotoxic agents, such as acyclovir. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Concurrent administration with drugs that decrease renal function may increase concentrations of tenofovir. In addition, use with drugs that are also eliminated by active tubular secretion may increase concentrations of the co-administered drug. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate; a majority of the cases occurred in patients who had underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir containing products should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus, and urine glucose and protein.
Adagrasib: (Moderate) Coadministration of tenofovir disoproxil fumarate with adagrasib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and adagrasib is a P-gp inhibitor. (Moderate) Monitor for an increase in adverse effects from both drugs during concomitant use of adagrasib and cobicistat. Avoid concomitant use during adagrasib therapy initiation (approximately 8 days); concomitant use before steady state is achieved may increase adagrasib exposure and the risk for adagrasib-related adverse reactions. Adagrasib and cobicistat are both CYP3A substrates and strong CYP3A inhibitors. Concomitant use of a single 200 mg dose of adagrasib with another strong CYP3A inhibitor increased adagrasib exposure by approximately 4-fold, however, no clinically significant differences in pharmacokinetics are predicted at steady state.
Adefovir: (Major) Avoid coadministration of tenofovir disoproxil fumarate with adefovir. Both tenofovir and adefovir are primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Concurrent administration may increase concentrations of both drugs resulting in additive nephrotoxicity. Additionally, in the treatment of chronic hepatitis B, tenofovir should not be administered in combination with adefovir to avoid multi-drug resistance. If coadministration is necessary, patients should be carefully monitored for changes in serum creatinine and phosphorus, and urine glucose and protein. (Moderate) Patients who are concurrently taking adefovir with emtricitabine are at risk of developing lactic acidosis and severe hepatomegaly with steatosis. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination with antiretrovirals. A majority of these cases have been in women; obesity and prolonged nucleoside exposure may also be risk factors. Particular caution should be exercised when administering nucleoside analogs to any patient with known risk factors for hepatic disease; however, cases have also been reported in patients with no known risk factors. Suspend adefovir in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations).
Ado-Trastuzumab emtansine: (Major) Avoid coadministration of cobicistat with ado-trastuzumab emtansine if possible due to the risk of elevated exposure to the cytotoxic component of ado-trastuzumab emtansine, DM1. Delay ado-trastuzumab emtansine treatment until cobicistat has cleared from the circulation (approximately 3 half-lives of cobicistat) when possible. If concomitant use is unavoidable, closely monitor patients for ado-trastuzumab emtansine-related adverse reactions. The cytotoxic component of ado-trastuzumab emtansine, DM1, is metabolized mainly by CYP3A4 and to a lesser extent by CYP3A5; cobicistat is a strong CYP3A4 inhibitor. Formal drug interaction studies with ado-trastuzumab emtansine have not been conducted.
Afatinib: (Moderate) If the concomitant use of cobicistat and afatinib is necessary, monitor for afatinib-related adverse reactions. If the original dose of afatinib is not tolerated, consider reducing the daily dose of afatinib by 10 mg; resume the previous dose of afatinib as tolerated after discontinuation of cobicistat. The manufacturer of afatinib recommends permanent discontinuation of therapy for severe or intolerant adverse drug reactions at a dose of 20 mg per day, but does not address a minimum dose otherwise. Afatinib is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor; coadministration may increase plasma concentrations of afatinib. Administration with another P-gp inhibitor, given 1 hour before a single dose of afatinib, increased afatinib exposure by 48%; there was no change in afatinib exposure when the P-gp inhibitor was administered at the same time as afatinib or 6 hours later. In healthy subjects, the relative bioavailability for AUC and Cmax of afatinib was 119% and 104%, respectively, when coadministered with the same P-gp inhibitor, and 111% and 105% when the inhibitor was administered 6 hours after afatinib.
Albuterol; Budesonide: (Moderate) Avoid coadministration of oral budesonide and cobistat due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Elevated budesonide serum concentrations may result in Cushing's syndrome and adrenal suppression. Budesonide is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and P-gp. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Aldesleukin, IL-2: (Moderate) Caution is warranted when cobicistat is administered with aldesleukin, IL-2 as there is a potential for elevated cobicistat concentrations. Aldesleukin, IL-2 is a CYP3A4 inhibitor and cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with aldesleukin, IL-2 as there is a potential for elevated elvitegravir concentrations. Aldesleukin, IL-2 is a CYP3A4 inhibitor and elvitegravir is a substrate of CYP3A4.
Alfentanil: (Moderate) The plasma concentrations of alfentanil may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as hypotension, nausea, itching, and respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor and alfentanil is a CYP3A4 substrate.
Alfuzosin: (Contraindicated) Alfuzosin is contraindicated for use with cobicistat due to the potential for serious/life-threatening reactions, including hypotension. Coadministration is expected to reduce the metabolism and increase systemic exposure to alfuzosin. Alfuzosin is primarily metabolized by CYP3A4; cobicistat is a strong inhibitor of this enzyme. Coadministration of another strong CYP3A4 inhibitor increased the alfuzosin AUC by 2.5-fold to 3.2-fold.
Aliskiren: (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor and aliskiren is a CYP3A4 and P-gp substrate.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor and aliskiren is a CYP3A4 and P-gp substrate.
Almotriptan: (Moderate) The maximum recommended starting dose of almotriptan is 6.25 mg if coadministration with cobicistat is necessary; do not exceed 12.5 mg within a 24-hour period. Concomitant use of almotriptan and cobicistat should be avoided in patients with renal or hepatic impairment. Almotriptan is a CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased almotriptan exposure by approximately 60%.
Alogliptin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Alosetron: (Moderate) Concomitant use of alosetron with cobicistat may result in increased serum concentrations of alosetron and increase the risk for adverse reactions. Caution and close monitoring are advised if these drugs are used together. Alosetron is a substrate of hepatic isoenzyme CYP3A4; cobicistat is a strong inhibitor of this enzyme. In a study of healthy female subjects, another strong CYP3A4 inhibitor increased mean alosetron AUC by 29%.
Alpelisib: (Major) Avoid coadministration of alpelisib with cobicistat due to increased exposure to alpelisib and the risk of alpelisib-related toxicity. If concomitant use is unavoidable, closely monitor for alpelisib-related adverse reactions. Alpelisib is a BCRP substrate and cobicistat is a BCRP inhibitor.
Alprazolam: (Contraindicated) Coadministration of cobicistat and alprazolam is contraindicated due to the potential for elevated alprazolam concentrations, which may cause prolonged sedation and respiratory depression. Lorazepam, oxazepam, or temazepam may be safer alternatives if a benzodiazepine must be administered in combination with cobicistat, as these benzodiazepines are not oxidatively metabolized. Alprazolam is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased alprazolam exposure by 2.7- to 3.98-fold.
Amikacin: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as aminoglycosides. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and aminoglycosides are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Aminoglycosides: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as aminoglycosides. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and aminoglycosides are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Aminosalicylate sodium, Aminosalicylic acid: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Amiodarone: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of amiodarone with cobicistat. Amiodarone is a substrate and inhibitor of CYP3A4 and an inhibitor CYP2D6, cobicistat is a substrate and strong inhibitor of CYP3A and CYP2D6. Concurrent use may result in elevated concentration of both drugs. (Moderate) Coadministration of tenofovir disoproxil fumarate with amiodarone may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and amiodarone is a P-gp inhibitor.
Amitriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Amlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Amlodipine; Atorvastatin: (Major) When administering atorvastatin concurrently with cobicistat, use the lowest starting dose of atorvastatin and carefully titrate while monitoring for adverse events (myopathy); DO NOT exceed a maximum daily atorvastatin dose of 20 mg daily. Cobicistat is a strong CYP3A4 inhibitor and atorvastatin is a CYP3A4 substrate. Coadministration with other strong CYP3A4 inhibitors increased atorvastatin exposure by 3.3- to 4.4-fold. (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Amlodipine; Benazepril: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Amlodipine; Celecoxib: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent. (Moderate) The plasma concentrations of celecoxib may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased analgesic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while celecoxib is a CYP2C9 substrate.
Amlodipine; Olmesartan: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Amlodipine; Valsartan: (Moderate) Caution is warranted when elvitegravir is administered with valsartan as there is a potential for decreased valsartan concentrations. Valsartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Caution is warranted when elvitegravir is administered with valsartan as there is a potential for decreased valsartan concentrations. Valsartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
Amoxicillin; Clarithromycin; Omeprazole: (Major) Avoid concurrent use of clarithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of clarithromycin, cobicistat, atazanavir and darunavir. Both clarithromycin and cobicistat are inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as clarithromycin. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
Amphotericin B lipid complex (ABLC): (Minor) Additive nephrotoxicity can also occur if amphotericin B is given concomitantly with tenofovir. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Amphotericin B liposomal (LAmB): (Minor) Additive nephrotoxicity can also occur if amphotericin B is given concomitantly with tenofovir. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Amphotericin B: (Minor) Additive nephrotoxicity can also occur if amphotericin B is given concomitantly with tenofovir. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Antacids: (Moderate) Separate administration of elvitegravir and antacids by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Apalutamide: (Major) Coadministration of cobicistat with apalutamide is not recommended as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. In addition, there is a potential for increased apalutamide exposure. If these drugs are used together, monitor for an increase in apalutamide-related adverse reactions. Consider reducing the dose of apalutamide if necessary based on tolerability in patients experiencing grade 3 or higher adverse reactions or intolerable toxicities. Apalutamide is a substrate and strong inducer of CYP3A4. Cobicistat is a substrate and strong inhibitor of CYP3A4. Coadministration with one strong CYP3A4 inhibitor decreased the Cmax of single-dose apalutamide by 22% and the AUC remained similar. Concomitant use with another strong CYP3A4 inhibitor is predicted to increase the single-dose apalutamide AUC by 24% but have no effect on Cmax; the steady-state Cmax and AUC are predicted to increase by 38% and 51%, respectively. The steady-state exposure of the active moieties (unbound apalutamide plus potency-adjusted unbound N-desmethyl apalutamide) is predicted to increase by 28%. (Major) Coadministration of elvitegravir with apalutamide is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is metabolized by CYP3A4 and apalutamide is a strong CYP3A4 inducer.
Apixaban: (Major) Reduce the apixaban dose by 50% when coadministered with drugs that are both strong inhibitors of CYP3A4 and P-gp, such as cobicistat containing medications. If patients are already receiving 2.5 mg twice daily, avoid concomitant administration. Concomitant administration results in increased exposure to apixaban and an increase in the risk of bleeding.
Aprepitant, Fosaprepitant: (Major) Avoid the concomitant use due to substantially increased exposure of aprepitant; increased cobicistat exposure may also occur. If coadministration cannot be avoided, use caution and monitor for an increase in cobicistat- and aprepitant-related adverse effects for several days after administration of a multi-day aprepitant regimen. After administration, fosaprepitant is rapidly converted to aprepitant and shares the same drug interactions. Cobicistat is a strong CYP3A4 inhibitor and aprepitant is a CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased the AUC of aprepitant by approximately 5-fold, and the mean terminal half-life by approximately 3-fold. Cobicistat is also a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor. When administered as a single oral or single intravenous dose, the inhibitory effect of aprepitant on CYP3A4 is weak and did not result in a clinically significant increase in the AUC of a sensitive substrate. (Major) Use caution if elvitegravir and aprepitant, fosaprepitant are used concurrently and monitor for an increase in elvitegravir-related adverse effects for several days after administration of a multi-day aprepitant regimen. Elvitegravir is a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer and may increase plasma concentrations of elvitegravir. For example, a 5-day oral aprepitant regimen increased the AUC of another CYP3A4 substrate, midazolam (single dose), by 2.3-fold on day 1 and by 3.3-fold on day 5. After a 3-day oral aprepitant regimen, the AUC of midazolam (given on days 1, 4, 8, and 15) increased by 25% on day 4, and then decreased by 19% and 4% on days 8 and 15, respectively. As a single 125 mg or 40 mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.5-fold and 1.2-fold, respectively. After administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. However, as a single 150 mg intravenous dose, fosaprepitant only weakly inhibits CYP3A4 for a duration of 2 days; there is no evidence of CYP3A4 induction. Fosaprepitant 150 mg IV as a single dose increased the AUC of midazolam (given on days 1 and 4) by approximately 1.8-fold on day 1; there was no effect on day 4. Less than a 2-fold increase in the midazolam AUC is not considered clinically important.
Aripiprazole: (Major) Recommendations for managing aripiprazole and cobicistat vary by aripiprazole dosage form. For aripiprazole oral dosage forms, administer a quarter of the usual dose. For monthly extended-release aripiprazole injections (Abilify Maintena), reduce the dosage from 400 mg to 200 mg/month or from 300 mg to 160 mg/month. For extended-release aripiprazole injections given once every 2 months (Abilify Asimtufii), reduce the dosage from 960 mg to 720 mg; avoid use in patients known to be poor metabolizers of CYP2D6. Further dosage reductions may be required in patients who are also receiving a strong CYP2D6 inhibitor; see individual product prescribing information for details. Concomitant use may increase aripiprazole exposure and risk for side effects. Aripiprazole is CYP2D6 and CYP3A substrate; cobicistat is a weak CYP2D6 and strong CYP3A inhibitor. (Major) Recommendations for managing aripiprazole and cobicistat vary by aripiprazole dosage form. For extended-release aripiprazole lauroxil injections (Aristada), reduce the dose to the next lowest strength; no dosage adjustment is required for patients tolerating 441 mg. For extended-release aripiprazole lauroxil injections (Aristada) in patients who are known to be poor metabolizers of CYP2D6, reduce the dose to 441 mg; no dosage adjustment is necessary for patients already tolerating 441 mg. For fixed dose extended-release aripiprazole lauroxil injections (Aristada Initio), avoid concomitant use because the dose cannot be modified. Further dosage reductions may be required in patients who are also receiving a strong CYP2D6 inhibitor; see individual product prescribing information for details. Concomitant use may increase aripiprazole exposure and risk for side effects. Aripiprazole is CYP2D6 and CYP3A substrate; cobicistat is a weak CYP2D6 and strong CYP3A inhibitor.
Armodafinil: (Major) Coadministration of cobicistat with armodafinil is not recommended as there is a potential for elevated armodafinil concentrations and decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Armodafinil is a CYP3A4 substrate/inducer and a P-glycoprotein (P-gp) substrate. Cobicistat is an inhibitor of CYP3A4 and P-gp, and a substrate of CYP3A4. (Major) Coadministration of with armodafinil is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Armodafinil is a CYP3A4 inducer, while elvitegravir is a substrate of CYP3A4.
Artemether; Lumefantrine: (Moderate) Caution is warranted when cobicistat with artemether; lumefantrine as there is a potential for elevated artemether, lumefantrine, and cobicistat concentrations. Both artemether and lumefantrine are CYP3A4 substrate and lumefantrine is CYP2D6 inhibitor. Cobicistat is a strong inhibitor of CYP3A4 and a substrate of CYP2D6. Coadministration with another strong CYP3A4 inhibitor increased lumefantrine exposure by 1.6-fold. (Moderate) Caution is warranted when cobicistat with artemether; lumefantrine as there is a potential for elevated artemether, lumefantrine, and cobicistat concentrations. Both artemether and lumefantrine are CYP3A4 substrates and lumefantrine is CYP2D6 inhibitor. Cobicistat is a strong inhibitor of CYP3A4 and a substrate of CYP2D6. In a drug interaction study, administration of a strong CYP3A4 inhibitor, resulted in a moderate increase in exposure to artemether, DHA, and lumefantrine.
Asciminib: (Moderate) Closely monitor for asciminib-related adverse reactions if concurrent use of asciminib 200 mg twice daily with cobicistat is necessary as asciminib exposure may increase. Asciminib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor.
Asenapine: (Moderate) Caution is warranted when cobicistat is administered with asenapine as there is a potential for increased aspenapine concentrations. Asenapine is a substrate of CYP3A4 and CYP2D6. Cobicistat is an inhibitor of CYP3A4 and CYP2D6.
Aspirin, ASA: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Aspirin, ASA; Butalbital; Caffeine: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Aspirin, ASA; Caffeine: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Aspirin, ASA; Caffeine; Orphenadrine: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Aspirin, ASA; Carisoprodol: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Aspirin, ASA; Carisoprodol; Codeine: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Aspirin, ASA; Citric Acid; Sodium Bicarbonate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus. (Moderate) Separate administration of elvitegravir and antacids by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Aspirin, ASA; Dipyridamole: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Aspirin, ASA; Omeprazole: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus. (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
Aspirin, ASA; Oxycodone: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus. (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone.
Atazanavir: (Moderate) Coadministration of atazanavir boosted with ritonavir and elvitagravir results in significantly elevated plasma concentrations of elvitegravir. The recommended dosing regimen for these drugs used in combination is: elvitegravir 85 mg PO once daily with atazanavir/ritonavir 300/100 mg PO once daily. No data are available for use of other dosage. (Moderate) Tenofovir decreases atazanavir AUC and Cmin. If atazanavir and tenofovir, PMPA are to be coadministered, it is recommended that atazanavir 300 mg be given with ritonavir 100 mg and tenofovir 300 mg once per day with food in patients >= 40 kg; atazanavir should not be coadministered with tenofovir without ritonavir. Data are insufficient to recommend atazanavir dosing in children < 40 kg who are also receiving concomitant tenofovir. In three post-marketing clinical trials, atazanavir AUC and Cmin were decreased by approximately 25% and 23 to 40%, respectively, when atazanavir was coadministered with tenofovir, PMPA as compared to atazanavir alone. Coadministration of atazanavir and tenofovir without ritonavir could lead to loss or lack of virologic response and possible resistance to atazanavir. In addition, atazanavir appears to increase tenofovir plasma concentrations, which could lead to adverse effects associated with tenofovir, including renal disorders. Increased tenofovir concentrations have been noted in the following combination regimens: tenofovir with ritonavir 'boosted' atazanavir; tenofovir, atazanavir, and lopinavir; ritonavir. Patients who receive tenofovir with atazanavir and any form/dose of ritonavir should be monitored for tenofovir-associated adverse events, with tenofovir being discontinued in patients who develop such adverse events. Although there are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir, the clinical significance of an interaction is suspected to be insignificant. In treatment-experienced patients >= 40 kg receiving H2-antagonists and tenofovir, atazanavir should be dosed 400 mg with ritonavir 100 mg once daily with food.
Atazanavir; Cobicistat: (Moderate) Coadministration of atazanavir boosted with ritonavir and elvitagravir results in significantly elevated plasma concentrations of elvitegravir. The recommended dosing regimen for these drugs used in combination is: elvitegravir 85 mg PO once daily with atazanavir/ritonavir 300/100 mg PO once daily. No data are available for use of other dosage. (Moderate) Tenofovir decreases atazanavir AUC and Cmin. If atazanavir and tenofovir, PMPA are to be coadministered, it is recommended that atazanavir 300 mg be given with ritonavir 100 mg and tenofovir 300 mg once per day with food in patients >= 40 kg; atazanavir should not be coadministered with tenofovir without ritonavir. Data are insufficient to recommend atazanavir dosing in children < 40 kg who are also receiving concomitant tenofovir. In three post-marketing clinical trials, atazanavir AUC and Cmin were decreased by approximately 25% and 23 to 40%, respectively, when atazanavir was coadministered with tenofovir, PMPA as compared to atazanavir alone. Coadministration of atazanavir and tenofovir without ritonavir could lead to loss or lack of virologic response and possible resistance to atazanavir. In addition, atazanavir appears to increase tenofovir plasma concentrations, which could lead to adverse effects associated with tenofovir, including renal disorders. Increased tenofovir concentrations have been noted in the following combination regimens: tenofovir with ritonavir 'boosted' atazanavir; tenofovir, atazanavir, and lopinavir; ritonavir. Patients who receive tenofovir with atazanavir and any form/dose of ritonavir should be monitored for tenofovir-associated adverse events, with tenofovir being discontinued in patients who develop such adverse events. Although there are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir, the clinical significance of an interaction is suspected to be insignificant. In treatment-experienced patients >= 40 kg receiving H2-antagonists and tenofovir, atazanavir should be dosed 400 mg with ritonavir 100 mg once daily with food.
Atogepant: (Major) Avoid use of atogepant and cobicistat when atogepant is used for chronic migraine. Limit the dose of atogepant to 10 mg PO once daily for episodic migraine if coadministered with cobicistat. Concurrent use may increase atogepant exposure and the risk of adverse effects. Atogepant is a substrate of CYP3A and OATP1B1/3; cobicistat is a strong CYP3A inhibitor and an OATP1B1/3 inhibitor. Coadministration with a strong CYP3A inhibitor resulted in a 5.5-fold increase in atogepant overall exposure and a 2.15-fold increase in atogepant peak concentration. Coadministration with an OATP1B1/3 inhibitor resulted in a 2.85-fold increase in atogepant overall exposure and a 2.23-fold increase in atogepant peak concentration.
Atomoxetine: (Moderate) The plasma concentrations of atomoxetine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as dizziness, drowsiness, hypertension, and other cardiac adverse events, is recommended during coadministration and dosage adjustments for atomoxetine may be warranted. Cobicistat is a CYP2D6 inhibitor and atomoxetine is a CYP2D6 substrate.
Atorvastatin: (Major) When administering atorvastatin concurrently with cobicistat, use the lowest starting dose of atorvastatin and carefully titrate while monitoring for adverse events (myopathy); DO NOT exceed a maximum daily atorvastatin dose of 20 mg daily. Cobicistat is a strong CYP3A4 inhibitor and atorvastatin is a CYP3A4 substrate. Coadministration with other strong CYP3A4 inhibitors increased atorvastatin exposure by 3.3- to 4.4-fold.
Atorvastatin; Ezetimibe: (Major) When administering atorvastatin concurrently with cobicistat, use the lowest starting dose of atorvastatin and carefully titrate while monitoring for adverse events (myopathy); DO NOT exceed a maximum daily atorvastatin dose of 20 mg daily. Cobicistat is a strong CYP3A4 inhibitor and atorvastatin is a CYP3A4 substrate. Coadministration with other strong CYP3A4 inhibitors increased atorvastatin exposure by 3.3- to 4.4-fold.
Avacopan: (Major) Reduce the dose of avacopan to 30 mg once daily if concomitant use of cobicistat is necessary. Concomitant use may increase avacopan exposure and risk for avacopan-related adverse effects. Avacopan is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use of another strong CYP3A inhibitor increased avacopan overall exposure 2.19-fold.
Avanafil: (Major) Do not use avanafil in patients receiving cobicistat due to the risk for increased avanafil serum concentrations and serious adverse reactions. Avanafil is a sensitive CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of other strong CYP3A4 inhibitors increased the avanafil AUC by 13-fold.
Avapritinib: (Major) Avoid coadministration of avapritinib with cobicistat due to the risk of increased avapritinib-related adverse reactions. Avapritinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor is predicted to increase the AUC of avapritinib by 600% at steady-state.
Axitinib: (Major) Avoid coadministration of axitinib with cobicistat due to the risk of increased axitinib-related adverse reactions. If coadministration is unavoidable, decrease the dose of axitinib by approximately half; subsequent doses can be increased or decreased based on individual safety and tolerability. Resume the original dose of axitini

b approximately 3 to 5 half-lives after cobicistat is discontinued. Axitinib is a CYP3A4/5 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4/5 inhibitor significantly increased the plasma exposure of axitinib in healthy volunteers.
Azelastine; Fluticasone: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate.
Bacitracin: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as bacitracin. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Bedaquiline: (Major) Concurrent use of bedaquiline and cobicistat should be avoided due to the potential risk of adverse reactions to bedaquiline because of increased systemic exposure. Bedaquiline is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Concurrent use of another strong CYP3A4 inhibitor increased bedaquiline exposure by 22%.
Benzhydrocodone; Acetaminophen: (Moderate) Concurrent use of benzhydrocodone with cobicistat may increase the risk of increased opioid-related adverse reactions, such as fatal respiratory depression. Consider a dose reduction of benzhydrocodone until stable drug effects are achieved. Monitor patients for respiratory depression and sedation at frequent intervals. Discontinuation of cobicistat in a patient taking benzhydrocodone may decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to opioid agonists. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Benzhydrocodone is a prodrug for hydrocodone. Hydrocodone is a substrate for CYP3A4 and CYP2D6. Cobicistat is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Berotralstat: (Major) Reduce the berotralstat dose to 110 mg PO once daily in patients chronically taking cobicistat. Concurrent use may increase berotralstat exposure and the risk of adverse effects. Additionally, monitor for cobicistat-related adverse effects as concurrent use may also increase cobicistat exposure. Berotralstat is a P-gp and BCRP substrate and moderate CYP3A4 inhibitor; cobicistat is a CYP3A4 substrate and P-gp and BCRP inhibitor. Coadministration with another P-gp and BCRP inhibitor increased berotralstat exposure by 69%. (Moderate) Coadministration of tenofovir disoproxil fumarate with berotralstat may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and berotralstat is a P-gp inhibitor.
Betamethasone: (Moderate) Monitor for corticosteroid-related adverse effects if coadministration is necessary. Consider using an alternative treatment to betametasone, such as a corticosteroid less affected by CYP3A4 (i.e., beclomethasone or prednisolone), particularly if long term use is indicated. Cobicistat is a strong CYP3A4 inhibitor and betamethasone is a CYP3A4 substrate. Another strong CYP3A4 inhibitor has been reported to decrease the metabolism of certain corticosteroids by up to 60%, leading to increased risk of corticosteroid side effects.
Betrixaban: (Major) Avoid betrixaban use in patients with severe renal impairment receiving cobicistat. Reduce betrixaban dosage to 80 mg PO once followed by 40 mg PO once daily in all other patients receiving cobicistat. Bleeding risk may be increased; monitor patients closely for signs and symptoms of bleeding. Betrixaban is a substrate of P-gp; cobicistat inhibits P-gp.
Bexarotene: (Major) Coadministration of cobicistat with bexarotene is not recommended as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Bexarotene is a CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Major) Coadministration of elvitegravir with bexarotene is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Bexarotene is a CYP3A4 inducer, while elvitegravir is a substrate of CYP3A4.
Bismuth Subsalicylate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Bismuth Subsalicylate; Metronidazole; Tetracycline: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Bortezomib: (Moderate) Monitor for signs of bortezomib toxicity and consider a bortezomib dose reduction if coadministration of cobicistat is necessary. Bortezomib exposure may be increased. Bortezomib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased bortezomib exposure by 35%.
Bosentan: (Major) Coadministation of bosentan with elvitegravir may result in elevated bosentan plasma concentrations and reduced elvitegravir concentrations. In patients receiving the antiretroviral for at least 10 days, start bosentan at 62.5 mg daily or every other day (depending on tolerability). When the antiretroviral is initiated in a patients currently receiving bosentan, discontinue bosentan at least 36 hours prior to starting the antiretroviral. After at least 10 days, restart bosentan at 62.5 mg daily or every other day based on tolerability. (Major) The plasma concentrations of bosentan may increase when administered with regimens containing cobicistat and atazanavir or darunavir. In addition, coadministration may result in decreased concentrations of cobicistat, atazanavir, and darunavir. In patients receiving the antiretrovirals for at least 10 days, start bosentan at 62.5 mg daily or every other day (depending on tolerability). When the antiretrovirals are initiated in a patients currently receiving bosentan, discontinue bosentan at least 36 hours prior to starting the antiretroviral regimen. After at least 10 days, restart bosentan at 62.5 mg daily or every other day based on tolerability. If switching from a ritonavir boosted antiretroviral regimen to a cobicistat boosted regimen, maintain current bosentan dose.
Bosutinib: (Major) Avoid concomitant use of bosutinib and cobicistat; bosutinib plasma exposure may be significantly increased resulting in an increased risk of bosutinib adverse events (e.g., myelosuppression, GI toxicity). Bosutinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The Cmax and AUC values of bosutinib were increased 5.2-fold and 8.6-fold, respectively, when a single oral dose of bosutinib 100 mg PO was administered after 5 days of a strong CYP3A4 inhibitor.
Brentuximab vedotin: (Moderate) Closely monitor for an increase in brentuximab-related adverse reactions, including peripheral neuropathy or gastrointestinal side effects, if coadministration with cobicistat is necessary. Monomethyl auristatin E (MMAE), one of the 3 components released from brentuximab vedotin, is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased MMAE exposure by approximately 34%.
Brexpiprazole: (Major) Because brexpiprazole is primarily metabolized by CYP3A4 and CYP2D6, the manufacturer recommends that the brexpiprazole dose be reduced to one-quarter (25%) of the usual dose in patients receiving a moderate to strong inhibitor of CYP3A4 in combination with a moderate to strong inhibitor of CYP2D6. Cobicistat is a moderate to strong inhibitor of both CYP3A4 and CYP2D6. If these agents are used in combination, the patient should be carefully monitored for brexpiprazole-related adverse reactions. If cobicistat is discontinued, adjust the brexpiprazole dosage to its original level.
Brigatinib: (Major) Avoid coadministration of brigatinib with cobicistat if possible due to increased plasma exposure of brigatinib; an increase in brigatinib-related adverse reactions may occur. If concomitant use is unavoidable, reduce the dose of brigatinib by approximately 50% without breaking tablets (i.e., from 180 mg to 90 mg; from 90 mg to 60 mg); after discontinuation of cobicistat, resume the brigatinib dose that was tolerated prior to initiation of cobicistat. Brigatinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the AUC and Cmax of brigatinib by 101% and 21%, respectively. (Moderate) Monitor for an increase in tenofovir-related adverse reactions if coadministration with brigatinib is necessary. Tenofovir disoproxil fumarate is a substrate of P-glycoprotein (P-gp) and BCRP. Brigatinib inhibits both P-gp and BCRP in vitro and may have the potential to increase concentrations of substrates of these transporters.
Brimonidine; Timolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as timolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
Brincidofovir: (Moderate) Postpone the administration of cobicistat for at least three hours after brincidofovir administration and increase monitoring for brincidofovir-related adverse reactions (i.e., elevated hepatic enzymes and bilirubin, diarrhea, other gastrointestinal adverse events) if concomitant use of brincidofovir and cobicistat is necessary. Brincidofovir is an OATP1B1/3 substrate and cobicistat is an OATP1B1/3 inhibitor. In a drug interaction study, the mean AUC and Cmax of brincidofovir increased by 374% and 269%, respectively, when administered with another OATP1B1/3 inhibitor.
Bromocriptine: (Major) When bromocriptine is used for diabetes, avoid coadministration with cobicistat ensuring adequate washout before initiating bromocriptine. Use this combination with caution in patients receiving bromocriptine for other indications. Concurrent use may significantly increase bromocriptine concentrations. Bromocriptine is extensively metabolized in the liver via CYP3A4; cobicistat is a strong inhibitor of CYP3A4.
Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Budesonide: (Moderate) Avoid coadministration of oral budesonide and cobistat due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Elevated budesonide serum concentrations may result in Cushing's syndrome and adrenal suppression. Budesonide is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and P-gp. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Budesonide; Formoterol: (Moderate) Avoid coadministration of oral budesonide and cobistat due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Elevated budesonide serum concentrations may result in Cushing's syndrome and adrenal suppression. Budesonide is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and P-gp. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Avoid coadministration of oral budesonide and cobistat due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Elevated budesonide serum concentrations may result in Cushing's syndrome and adrenal suppression. Budesonide is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and P-gp. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Bupivacaine Liposomal: (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
Bupivacaine: (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
Bupivacaine; Epinephrine: (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
Bupivacaine; Lidocaine: (Moderate) Monitor for lidocaine-related adverse reactions if coadministration with cobicistat is necessary. Lidocaine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
Bupivacaine; Meloxicam: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Caution is warranted when elvitegravir is administered with meloxicam as there is a potential for decreased meloxicam concentrations. Meloxicam is primarily metabolized by CYP2C9, while elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
Buprenorphine: (Moderate) Concomitant use of buprenorphine and cobicistat can increase the plasma concentration of buprenorphine, resulting in increased or prolonged opioid effects, particularly when cobicistat is added after a stable buprenorphine dose is achieved. If concurrent use is necessary, consider dosage reduction of buprenorphine until stable drug effects are achieved. Monitor patient for respiratory depression and sedation at frequent intervals. When stopping cobicistat, the buprenorphine concentration may decrease, potentially resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependency. If cobicistat is discontinued, consider increasing buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. Buprenorphine is a substrate of CYP3A and cobicistat is a CYP3A inhibitor. (Moderate) The plasma concentrations of buprenorphine and its metabolite, norbuprenorphine, are elevated when administered concurrently with elvitegravir. Dose adjustments are not required; however clinical monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration.
Buprenorphine; Naloxone: (Moderate) Concomitant use of buprenorphine and cobicistat can increase the plasma concentration of buprenorphine, resulting in increased or prolonged opioid effects, particularly when cobicistat is added after a stable buprenorphine dose is achieved. If concurrent use is necessary, consider dosage reduction of buprenorphine until stable drug effects are achieved. Monitor patient for respiratory depression and sedation at frequent intervals. When stopping cobicistat, the buprenorphine concentration may decrease, potentially resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependency. If cobicistat is discontinued, consider increasing buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. Buprenorphine is a substrate of CYP3A and cobicistat is a CYP3A inhibitor. (Moderate) The plasma concentrations of buprenorphine and its metabolite, norbuprenorphine, are elevated when administered concurrently with elvitegravir. Dose adjustments are not required; however clinical monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. (Moderate) The plasma concentrations of buprenorphine and naloxone may be elevated when administered concurrently with cobicistat. When initiating buprenorphine; naloxone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest buprenorphine; naloxone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on buprenorphine; naloxone, an adjustment of buprenorphine; naloxone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while buprenorphine is a CYP3A4 substrate.
Bupropion: (Moderate) Caution is warranted when cobicistat is administered with bupropion as there is a potential for elevated cobicistat concentrations. Bupropion is a CYP2D6 inhibitor in vitro, while cobicistat is a substrate of CYP2D6.
Bupropion; Naltrexone: (Moderate) Caution is warranted when cobicistat is administered with bupropion as there is a potential for elevated cobicistat concentrations. Bupropion is a CYP2D6 inhibitor in vitro, while cobicistat is a substrate of CYP2D6.
Buspirone: (Moderate) A low dose of buspirone used cautiously is recommended when coadministered with cobicistat. If a patient has been titrated to a stable dosage of buspirone, a dose adjustment of buspirone may be necessary to avoid adverse events attributable to buspirone. Administering cobicistat with buspirone may increase buspirone concentration and risk for adverse events. Buspirone is a sensitive substrate of CYP3A4. Cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the buspirone AUC by 19-fold with an increased incidence of buspirone-related adverse effects.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Butalbital; Aspirin; Caffeine; Codeine: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Cabazitaxel: (Major) Avoid coadministration of cabazitaxel with cobicistat if possible due to increased cabazitaxel exposure. If concomitant use is unavoidable, consider reducing the dose of cabazitaxel by 25%. Cabazitaxel is primarily metabolized by CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with another strong CYP3A4 inhibitor increased cabazitaxel exposure by 25%.
Cabotegravir; Rilpivirine: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
Cabozantinib: (Major) Avoid concomitant use of cabozantinib and cobicistat due to the risk of increased cabozantinib exposure which may increase the incidence and severity of adverse reactions. If concomitant use is unavoidable, reduce the dose of cabozantinib. For patients taking cabozantinib tablets, reduce the dose of cabozantinib by 20 mg; for patients taking cabozantinib capsules, reduce the dose of cabozantinib by 40 mg. Resume the cabozantinib dose that was used prior to initiating treatment with cobicistat 2 to 3 days after discontinuation of cobicistat. Cabozantinib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased cabozantinib exposure by 38%. (Minor) Monitor for an increase in both cabozantinib- and tenofovir-related adverse reactions if coadministration is necessary. Cabozantinib is a Multidrug Resistance Protein 2 (MRP2) substrate and tenofovir is an MRP2 inhibitor. MRP2 inhibitors have the potential to increase plasma concentrations of cabozantinib. Cabozantinib is also P-gp inhibitor and has the potential to increase plasma concentrations of P-gp substrates such as tenofovir. The clinical relevance of either of these interactions is unknown.
Calcium (oral): (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium Acetate: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium Carbonate: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium Carbonate; Famotidine; Magnesium Hydroxide: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium Carbonate; Magnesium Hydroxide: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium Carbonate; Magnesium Hydroxide; Simethicone: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium Carbonate; Simethicone: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium Gluconate: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Calcium; Vitamin D: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Canagliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Cannabidiol: (Moderate) Coadministration of tenofovir disoproxil fumarate with cannabidiol may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and cannabidiol is a P-gp inhibitor.
Capmatinib: (Moderate) Coadministration of tenofovir disoproxil fumarate with capmatinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-glycoprotein (P-gp) and BCRP substrate and capmatinib is a P-gp and BCRP inhibitor. (Moderate) Monitor for an increase in capmatinib-related adverse reactions if coadministration with cobicistat is necessary. Capmatinib is a CYP3A substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased capmatinib exposure by 42%.
Carbamazepine: (Contraindicated) Coadministration of carbamazepine with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. In addition, inhibition of CYP3A4 by cobicistat may result in elevated carbamazepine concentrations. Consider use of an alternative anticonvulsant or antiretroviral therapy. (Major) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Carbamazepine induces the CYP3A4 metabolism of elvitegravir. Consider an alternative anticonvulsant when using elvitegravir. The combination product cobicistat; elvitegravir; emtricitabine; tenofovir is contraindicated in combination with carbamazepine as the concentrations of both elvitegravir and cobicistat may be significantly decreased.
Carboplatin: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as carboplatin. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Cariprazine: (Major) The dose of cariprazine should be reduced in patients also receiving cobicistat. When cobicistat is initiated in a patient who is on a stable dose of cariprazine, reduce the cariprazine dosage by half. For adult patients taking cariprazine 4.5 mg daily, the dosage should be reduced to 1.5 mg or 3 mg daily. For patients taking cariprazine 1.5 mg daily, the dosing frequency should be adjusted to every other day. When initiating cariprazine in a patient who is stable on cobicistat, the patient should be administered 1.5 mg of cariprazine on Day 1 and on Day 3 with no dose administered on Day 2. From Day 4 onward, the dose should be administered at 1.5 mg daily, and then increased to a maximum dose of 3 mg daily. If cobicistat is withdrawn, the cariprazine dosage may need to be increased. Cariprazine is metabolized by CYP3A4 to its major active metabolite. Cobicistat is a strong CYP3A4 inhibitor. Concurrent use with another strong CYP3A4 inhibitor increased the exposure of cariprazine by about 4-fold; increased the AUC of DDCAR metabolite by about 1.5-fold; and decreased DCAR metabolite AUC by about one-third.
Carvedilol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as carvedilol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advise. (Moderate) Increased concentrations of tenofovir may occur if it is coadministered with carvedilol; exercise caution. Carvedilol is a P-glycoprotein (P-gp) inhibitor and tenofovir is a P-gp substrate.
Celecoxib: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of celecoxib may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased analgesic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while celecoxib is a CYP2C9 substrate.
Celecoxib; Tramadol: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of celecoxib may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased analgesic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while celecoxib is a CYP2C9 substrate.
Cenobamate: (Moderate) Coadministration of cobicistat with cenobamate may result in significant decreases in the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is a CYP3A4 substrate and cenobamate is a moderate CYP3A4 inducer. (Moderate) Coadministration of elvitegravir with cenobamate may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is a CYP3A4 substrate and cenobamate is a moderate CYP3A4 inducer.
Ceritinib: (Major) Avoid concomitant use of ceritinib with cobicistat due to increased ceritinib exposure which may increase the incidence and severity of adverse reactions; cobicistat exposure may also increase. If concomitant use is necessary, decrease the dose of ceritinib by approximately one-third, rounded to the nearest multiple of 150 mg and monitor for ceritinib-related adverse reactions. After cobicistat is discontinued, resume the dose of ceritinib taken prior to initiating cobicistat. Both drugs are CYP3A substrates and strong CYP3A4 inhibitors. Coadministration with a strong CYP3A inhibitor increased ceritinib exposure by 2.9-fold.
Chloramphenicol: (Moderate) Caution is warranted when cobicistat is administered with chloramphenicol as there is a potential for elevated cobicistat concentrations. Chloramphenicol is a CYP3A4 inhibitor and cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with chloramphenicol as there is a potential for elevated elvitegravir concentrations. Chloramphenicol is a CYP3A4 inhibitor and elvitegravir is a substrate of CYP3A4.
Chlordiazepoxide: (Moderate) The plasma concentrations of chlordiazepoxide may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while chlordiazepoxide is a CYP3A4 substrate.
Chlordiazepoxide; Amitriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations. (Moderate) The plasma concentrations of chlordiazepoxide may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while chlordiazepoxide is a CYP3A4 substrate.
Chlordiazepoxide; Clidinium: (Moderate) The plasma concentrations of chlordiazepoxide may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while chlordiazepoxide is a CYP3A4 substrate.
Chlorpheniramine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Chlorpheniramine; Codeine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Chlorpheniramine; Dextromethorphan: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of dihydrocodeine with cobicistat may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
Chlorpheniramine; Hydrocodone: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Chlorpheniramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Chlorpheniramine; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Separate administration of elvitegravir and zinc by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Chlorpromazine: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Choline Salicylate; Magnesium Salicylate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Chromium: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Ciclesonide: (Moderate) Coadministration of ciclesonide with cobicistat may cause elevated ciclesonide serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Ciclesonide is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Cidofovir: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as cidofovir. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and cidofovir are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Tenofovir disoproxil fumarate should be avoided with concurrent or recent use of a nephrotoxic agent, such as cidofovir. If concurrent use is necessary, closely monitor for changes in renal function. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Concurrent administration with a drug that reduces renal function or competes for active tubular secretion may increase concentrations of tenofovir and other renally eliminated drugs; thus, increasing the risk of developing renal-related adverse events. Renal impairment, which may include acute renal failure and hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate.
Cilostazol: (Major) Reduce the dose of cilostazol to 50 mg twice daily when coadministered with cobicistat. Monitor for an increase in cilostazol-related adverse reactions. Cobicistat is a strong CYP3A4 inhibitor and cilostazol is a CYP3A4 substrate. Coadministration of another strong CYP3A4 inhibitor increased the cilostazol AUC by 117%.
Cimetidine: (Moderate) Caution is warranted when elvitegravir is administered with cimetidine as there is a potential for elevated elvitegravir concentrations. Cimetidine is a CYP3A4 and CYP2D6 inhibitor, while elvitegravir is a substrate of CYP3A4.
Cinacalcet: (Moderate) Monitor for cinacalcet-related adverse effects during concomitant use of cobicistat and adjust dosage as appropriate based on response. Concomitant use may increase cinacalcet exposure. Cinacalcet is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use with another strong CYP3A inhibitor increased cinacalcet overall exposure by 127%.
Cisapride: (Contraindicated) Coadministration of cisapride with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A4, and plasma concentrations of drugs extensively metabolized by this enzyme, such as cisapride, are expected to increase with concurrent use. Elevated plasma concentrations of cisapride have been associated with QT prolongation and serious cardiovascular adverse events including death due to torsade de pointes.
Cisplatin: (Major) Avoid tenofovir administration with concurrent or recent treatment with cisplatin. Cisplatin can cause nephrotoxicity. Tenofovir is primarily eliminated by the kidneys; drugs that decrease renal function may increase concentrations of tenofovir. Also, cases of acute renal failure after initiation of other nephrotoxic drugs have been reported in HIV-infected patients with risk factors for renal dysfunction who appeared stable on tenofovir treatment; some patients required hospitalization and renal replacement therapy.
Citalopram: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Clarithromycin: (Major) Avoid concurrent use of clarithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of clarithromycin, cobicistat, atazanavir and darunavir. Both clarithromycin and cobicistat are inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as clarithromycin. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Clindamycin: (Moderate) Concomitant use of tenofovir and clindamycin may result in additive nephrotoxicity. Monitor for renal toxicity if concomitant use is required. (Moderate) Monitor for an increase in clindamycin-related adverse reactions with coadministration of cobicistat as concurrent use may increase clindamycin exposure. Clindamycin is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4.
Clobazam: (Major) Coadministration of cobicistat with clobazam is not recommended. There is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Clobazam is a weak inducer of CYP3A4. Cobicistat is a substrate of CYP3A4. (Major) Coadministration of elvitegravir with clobazam is not recommended. There is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Clobazam is a weak inducer of CYP3A4. Elvitegravir is a substrate of CYP3A4.
Clofarabine: (Major) Avoid the concomitant use of clofarabine and tenofovir; coadministration may result in additive nephrotoxicity. Additionally, taking these drugs together may alter clofarabine concentrations; clofarabine and tenofovir are both substrates of OAT1 and OAT3.
Clomipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Clonazepam: (Moderate) Monitor for increased sedation and respiratory depression if clonazepam is coadministered with cobicistat; adjust the dose of clonazepam if necessary. The systemic exposure of clonazepam may be increased resulting in increase in treatment-related adverse reactions. Cobicistat is a strong CYP3A4 inhibitor and clonazepam is a CYP3A4 substrate.
Clopidogrel: (Major) Avoid coadministration of clopidogrel with cobicistat due to the potential for decreased clopidogrel efficacy. Prasugrel may be preferred to clopidogrel if coadministration with cobicistat is necessary. Although clopidogrel is primarily converted to its active metabolite via CYP2C19, it has been suggested that inhibition of CYP3A4 also reduces its conversion to the active metabolite, thereby reducing its antiplatelet effect. Cobicistat is a strong CYP3A4 inhibitor.
Clorazepate: (Moderate) Use caution if coadministration of cobicistat with clorazepate is necessary, as the systemic exposure of the active metabolite of clorazepate may be increased resulting in an increase in treatment-related adverse reactions; adjust the dose of clorazepate if necessary. Cobicistat is a strong CYP3A4 inhibitor. Clorazepate is a pro-drug converted to N-desmethyldiazepam in the GI tract; N-desmethyldiazepam is metabolized by 2C19 and 3A4.
Clozapine: (Moderate) Caution is advisable during concurrent use of cobicistat and clozapine. Cobicistat is an inhibitor of CYP2D6 and CYP3A4, two of the isoenzymes responsible for the metabolism of clozapine. Elevated plasma concentrations of clozapine occurring through CYP inhibition may potentially increase the risk of life-threatening arrhythmias, sedation, anticholinergic effects, seizures, orthostasis, or other adverse effects. According to the manufacturer, patients receiving clozapine in combination with a CYP3A4 or CYP2D6 inhibitor should be monitored for adverse reactions. Consideration should be given to reducing the clozapine dose if necessary. If the inhibitor is discontinued after dose adjustments are made, monitor for lack of clozapine effectiveness and consider increasing the clozapine dose if necessary.
Cobimetinib: (Major) Avoid the concurrent use of cobimetinib with chronic cobicistat due to the risk of cobimetinib toxicity. If concurrent short-term (14 days or less) use of cobicistat is unavoidable, reduce the dose of cobimetinib to 20 mg once daily for patients normally taking 60 mg daily; after discontinuation of cobicistat, resume cobimetinib at the previous dose. Use an alternative to cobicistat in patients who are already taking a reduced dose of cobimetinib (40 or 20 mg daily). Cobimetinib is a P-glycoprotein (P-gp) substrate as well as a CYP3A substrate in vitro; cobicistat is a moderate inhibitor of both P-gp and CYP3A. In healthy subjects (n = 15), coadministration of a single 10 mg dose of cobimetinib with itraconazole (200 mg once daily for 14 days), a strong CYP3A4 inhibitor, increased the mean cobimetinib AUC by 6.7-fold (90% CI, 5.6 to 8) and the mean Cmax by 3.2-fold (90% CI, 2.7 to 3.7).
Cocaine: (Moderate) Caution is warranted when cobicistat is administered with cocaine as there is a potential for elevated concentrations of both drugs. Clinical monitoring for adverse effects is recommended during coadministration. Both drugs are substrates and inhibitors of CYP3A4. Cocaine is also an inhibitor of CYP2D6; cobicistat is a CYP2D6 substrates/inhibitors. (Moderate) Caution is warranted when elvitegravir; is administered with cocaine as there is a potential for elevated concentrations of elvitegravir. Clinical monitoring for adverse effects is recommended during coadministration. Cocaine is an inhibitor of CYP3A4. Elvitegravir is a CYP3A4 substrate.
Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals an d consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Codeine; Guaifenesin: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Codeine; Phenylephrine; Promethazine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Codeine; Promethazine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
Colchicine: (Major) Due to the risk for serious colchicine toxicity including multi-organ failure and death, avoid coadministration of colchicine and cobicistat in patients with normal renal and hepatic function unless the use of both agents is imperative. Coadministration is contraindicated in patients with renal or hepatic impairment because colchicine accumulation may be greater in these populations. Cobicistat can inhibit colchicine's metabolism via P-glycoprotein (P-gp) and CYP3A4, resulting in increased colchicine exposure. If coadministration in patients with normal renal and hepatic function cannot be avoided, adjust the dose of colchicine by either reducing the daily dose or the dosage frequency, and carefully monitor for colchicine toxicity. Specific dosage adjustment recommendations are available for the Colcrys product for patients who have taken a P-gp/strong CYP3A4 inhibitor like cobicistat in the past 14 days or require concurrent use: for prophylaxis of gout flares, if the original dose is 0.6 mg twice daily, decrease to 0.3 mg once daily or if the original dose is 0.6 mg once daily, decrease to 0.3 mg once every other day; for treatment of gout flares, give 0.6 mg as a single dose, then 0.3 mg 1 hour later, and do not repeat for at least 3 days; for familial Mediterranean fever, do not exceed a 0.6 mg/day.
Colistimethate, Colistin, Polymyxin E: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as colistimethate sodium. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus, and urine glucose and protein.
Colistin: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as colistimethate sodium. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus, and urine glucose and protein.
Conivaptan: (Contraindicated) Coadministration of conivaptan and cobicistat is contraindicated due to the potential for increased conivaptan exposure. Concomitant use may also increase cobicistat exposure and risk for cobicistat-related adverse effects. Conivaptan is a CYP3A substrate and moderate CYP3A inhibitor; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. In a drug interaction study, coadministration of a strong CYP3A inhibitor increased the exposure of oral conivaptan by 11-fold. (Moderate) Use caution when administering conivaptan and tenofovir concurrently. Conivaptan is an inhibitor of P-glycoprotein (P-gp). Co-administration of conivaptan with P-gp substrates, such as tenofovir, PMPA, can increase tenofovir exposure leading to increased or prolonged therapeutic effects and adverse events.
Conjugated Estrogens; Medroxyprogesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with medroxyprogesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
Copanlisib: (Major) Avoid the concomitant use of copanlisib and cobicistat if possible; increased copanlisib exposure may occur. If coadministration cannot be avoided, reduce the copanlisib dose to 45 mg and monitor patients for copanlisib-related adverse events (e.g., hypertension, infection, and skin rash). Copanlisib is a CYP3A substrate; cobicistat is a strong CYP3A inhibitor. The AUC of copanlisib increased by 53% when a single IV dose of copanlisib 60 mg was administered following 10 days of another strong CYP3A4 inhibitor in a drug interaction study in patients with cancer.
Crizotinib: (Major) Avoid concomitant use of cobicistat and crizotinib due to increased plasma concentrations of crizotinib, which may increase the incidence and severity of adverse reactions; exposure to cobicistat may also increase. If concomitant use is necessary for adults with non-small cell lung cancer (NSCLC) or inflammatory myofibroblastic tumor (IMT), reduce the dose of crizotinib to 250 mg PO once daily. If concomitant use is necessary for young adult or pediatric patients with anaplastic large cell lymphoma or pediatric patients with IMT, reduce the dose of crizotinib to 250 mg PO twice daily for BSA of 1.7 m2 or more; 200 mg PO twice daily for BSA of 1.17 to 1.69 m2; and 250 mg PO once daily for BSA of 0.81 to 1.16 m2; do not use this combination in patients with a BSA of 0.6 to 0.8 m2. Resume the original crizotinib dose after discontinuation of cobicistat. Crizotinib is a CYP3A substrate and moderate inhibitor. Cobicistat is a CYP3A substrate and strong CYP3A inhibitor. Coadministration with one strong CYP3A inhibitor increased the AUC of single-dose crizotinib by 216%. Concomitant use with another strong CYP3A inhibitor increased the steady-state AUC of crizotinib by 57% compared to crizotinib alone.
Cyclosporine: (Major) Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, such as cyclosporine, should be carefully monitored for changes in serum creatinine and phosphorus. (Moderate) Cyclosporine therapeutic drug monitoring is recommended when administered concurrently with cobicistat. Use of these medications together may result in elevated cyclosporine serum concentrations, causing an increased risk for cyclosporine-related adverse events. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of cyclosporine.
Dabigatran: (Moderate) Monitor for an increase in dabigatran-related adverse reactions if coadministration with cobicistat is necessary in patients with creatinine clearance (CrCl) greater than 50 mL/minute. Avoid coadministration in patients with CrCl less than 50 mL/minute when dabigatran is administered for treatment or reduction in risk of recurrence of deep venous thrombosis (DVT) or pulmonary embolism (PE) or prophylaxis of DVT or PE following hip replacement surgery. Avoid coadministration in patients with CrCl less than 30 mL/minute in patients with non-valvular atrial fibrillation. Serum concentrations of dabigatran are expected to be higher in patients with renal impairment compared to patients with normal renal function. Dabigatran is a P-gp substrate and cobicistat is a P-gp inhibitor.
Dabrafenib: (Major) Avoid coadministration of dabrafenib and cobicistat due to the potential for decreased cobicistat concentrations and increased dabrafenib exposure. If another agent cannot be substituted and coadministration of these agents is unavoidable, monitor patients closely for reduced antiretroviral efficacy and dabrafenib adverse reactions including skin toxicity, ocular toxicity, and cardiotoxicity. Both drugs are CYP3A4 substrates. Darafenib is a moderate CYP3A4 inducer, while cobicistat is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration of a strong CYP3A4 inhibitor increased the dabrafenib AUC by 71%, hydroxy-dabrafenib AUC by 82%, and desmethyl-dabrafenib AUC by 68%. (Major) Coadministration of elvitegravir with dabrafenib is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is metabolized by CYP3A4; dabrafenib is a moderate CYP3A4 inducer.
Daclatasvir: (Major) The dose of daclatasvir, a CYP3A4 substrate, must be reduced to 30 mg PO once daily when administered in combination with strong CYP3A4 inhibitors, such as cobicistat. Taking these drugs together may increase daclatasvir serum concentrations, and potentially increase the risk for adverse effects.
Danazol: (Moderate) Caution is warranted when cobicistat is administered with danazol as there is a potential for elevated cobicistat concentrations. Danazol is a CYP3A4 inhibitor and cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when cobicistat is administered with danazol as there is a potential for elevated elvitegravir concentrations. Danazol is a CYP3A4 inhibitor and elvitegravir is a substrate of CYP3A4.
Dapagliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Dapagliflozin; Saxagliptin: (Major) Limit the dose of saxagliptin to 2.5 mg PO once daily when administered with cobicistat due to significantly increased saxagliptin exposure. Saxagliptin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 100 mg dose of saxagliptin and a single 20 mg dose of saxagliptin increased the saxagliptin AUC by 2.45-fold and 3.67-fold, respectively.
Dapsone: (Minor) Plasma concentrations of dapsone may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as hemolytic anemia, methemoglobinemia, or peripheral neuropathy, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while dapsone is a CYP3A4 substrate.
Daridorexant: (Major) Avoid concomitant use of daridorexant and cobicistat. Concomitant use may increase daridorexant exposure and the risk for daridorexant-related adverse effects. Daridorexant is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use of another strong CYP3A inhibitor increased daridorexant overall exposure by over 400%.
Darifenacin: (Major) The daily dose of darifenacin should not exceed 7.5 mg PO when administered with cobicistat due to increased darifenacin exposure. Darifenacin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor.
Darolutamide: (Moderate) Caution is advised with the coadministration of darolutamide and tenofovir disoproxil fumarate due to the potential for increased plasma concentrations of tenofovir disoproxil fumarate increasing the risk of adverse effects. Tenofovir disoproxil fumarate is a substrate of breast cancer resistance protein (BCRP) and darolutamide is a BCRP inhibitor. (Moderate) Monitor patients more frequently for darolutamide-related adverse reactions if coadministration with cobicistat is necessary due to the risk of increased darolutamide exposure; decrease the dose of darolutamide for grade 3 or 4 adverse reactions or for otherwise intolerable adverse reactions. Cobicistat is a P-glycoprotein (P-gp) inhibitor and a strong CYP3A4 inhibitor; darolutamide is a CYP3A4 substrate. Concomitant use with another combined P-gp inhibitor and strong CYP3A4 inhibitor increased the mean AUC and Cmax of darolutamide by 1.7-fold and 1.4-fold, respectively.
Darunavir: (Moderate) Coadministration of darunavir boosted with cobicistat and elvitegravir is not recommended. Dosing recommendations for such combinations have not been established and coadministration may result in decreased plasma concentrations of the antiretrovirals, resulting in reduction of antiretroviral efficacy and development of viral resistance. However, elvitegravir may be administered with darunavir if boosted with ritonavir. When elvitegravir is administered in combination with darunavir and ritonavir, the recommended dosing is: elvitegravir 150 mg PO once daily with darunavir/ritonavir 600/100 mg PO twice daily. No data are available for use of other dosage for this combination. (Moderate) Pharmacokinetic parameters (AUC, Cmax, Cmin) of tenofovir, PMPA are elevated when administered in combination with darunavir and ritonavir. The clinical significance of this interaction has not been established, and dosage adjustments are not recommended. Monitor the patients closely for tenofovir-related adverse events.
Darunavir; Cobicistat: (Moderate) Coadministration of darunavir boosted with cobicistat and elvitegravir is not recommended. Dosing recommendations for such combinations have not been established and coadministration may result in decreased plasma concentrations of the antiretrovirals, resulting in reduction of antiretroviral efficacy and development of viral resistance. However, elvitegravir may be administered with darunavir if boosted with ritonavir. When elvitegravir is administered in combination with darunavir and ritonavir, the recommended dosing is: elvitegravir 150 mg PO once daily with darunavir/ritonavir 600/100 mg PO twice daily. No data are available for use of other dosage for this combination. (Moderate) Pharmacokinetic parameters (AUC, Cmax, Cmin) of tenofovir, PMPA are elevated when administered in combination with darunavir and ritonavir. The clinical significance of this interaction has not been established, and dosage adjustments are not recommended. Monitor the patients closely for tenofovir-related adverse events.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Moderate) Coadministration of darunavir boosted with cobicistat and elvitegravir is not recommended. Dosing recommendations for such combinations have not been established and coadministration may result in decreased plasma concentrations of the antiretrovirals, resulting in reduction of antiretroviral efficacy and development of viral resistance. However, elvitegravir may be administered with darunavir if boosted with ritonavir. When elvitegravir is administered in combination with darunavir and ritonavir, the recommended dosing is: elvitegravir 150 mg PO once daily with darunavir/ritonavir 600/100 mg PO twice daily. No data are available for use of other dosage for this combination. (Moderate) Pharmacokinetic parameters (AUC, Cmax, Cmin) of tenofovir, PMPA are elevated when administered in combination with darunavir and ritonavir. The clinical significance of this interaction has not been established, and dosage adjustments are not recommended. Monitor the patients closely for tenofovir-related adverse events.
Dasatinib: (Major) Avoid coadministration of dasatinib and cobicistat due to the potential for increased dasatinib exposure and subsequent toxicity. An alternative to cobicistat with no or minimal enzyme inhibition potential is recommended if possible. If coadministration cannot be avoided, consider a dasatinib dose reduction to 40 mg PO daily if original dose was 140 mg daily, 20 mg PO daily if original dose was 100 mg daily, or 20 mg PO daily if original dose was 70 mg daily. Concomitant use of cobicistat is not recommended in patients receiving dasatinib 60 mg or 40 mg daily. If dasatinib is not tolerated after dose reduction, consider alternative therapies. If cobicistat is stopped, allow a washout of approximately 1 week before increasing the dasatinib dose. Dasatinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the mean Cmax and AUC of dasatinib by 4-fold and 5-fold, respectively.
Deflazacort: (Major) Decrease deflazacort dose to one third of the recommended dosage when coadministered with cobicistat. Concurrent use may significantly increase concentrations of 21-desDFZ , the active metabolite of deflazacort, resulting in an increased risk of toxicity. Deflazacort is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Administration of deflazacort with another strong CYP3A4 inhibitor, increased total exposure to 21-desDFZ by about 3-fold.
Delavirdine: (Moderate) The plasma concentrations of delavirdine and cobicistat may be elevated when administered concurrently. Clinical monitoring for adverse effects is recommended during coadministration. Delavirdine is a CYP2D6 and CYP3A4 substrate/inhibitor. Cobicistat is a substrate/inhibitor of both CYP2D6 and CYP3A4.
Desipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Desogestrel; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with desogestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Desvenlafaxine: (Moderate) Caution is warranted when cobicistat is administered with desvenlafaxine as there is a potential for elevated cobicistat concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Desvenlafaxine is an inhibitor of CYP2D6; cobicistat is partially metabolized by CYP2D6.
Dexamethasone: (Major) Avoid concurrent use of dexamethasone with cobicistat-containing regimens due to the risk of decreased antiretroviral efficacy and the potential development of viral resistance. In addition, serum concentrations of dexamethasone may be increased, potentially resulting in Cushing's syndrome and adrenal suppression. Consider an alternative corticosteroid (i.e., beclomethasone, prednisone, prednisolone) for long-term use. If concomitant use is necessary, monitor virologic response and for corticosteroid-related adverse effects. Dexamethasone is a CYP3A4 substrate and weak CYP3A inducer; cobicistat is a CYP3A4 substrate and strong CYP3A inhibitor. Another strong CYP3A inhibitor has been reported to decrease the metabolism of certain corticosteroids by up to 60%, leading to increased risk of corticosteroid side effects. (Moderate) Monitor for a decrease in elvitegravir efficacy during concurrent use of elvitegravir and dexamethasone. If long term coadministration is required, consider using an alternative corticosteroid, such as prednisone or prednisolone. Concomitant use may decrease elvitegravir exposure leading to potential loss of virologic control. Elvitegravir is a CYP3A substrate and dexamethasone is a weak CYP3A inducer.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dexlansoprazole: (Minor) The plasma concentrations of dexlansoprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dexlansoprazole is a CYP3A4 substrate.
Dextromethorphan: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dextromethorphan; Bupropion: (Moderate) Caution is warranted when cobicistat is administered with bupropion as there is a potential for elevated cobicistat concentrations. Bupropion is a CYP2D6 inhibitor in vitro, while cobicistat is a substrate of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Caution is warranted when elvitegravir is administered with diphenhydramine as there is a potential for decreased diphenhydramine concentrations. Diphenhydramine is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dextromethorphan; Guaifenesin: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dextromethorphan; Guaifenesin; Potassium Guaiacolsulfonate: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Dextromethorphan; Quinidine: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of quinidine with cobicistat. Quinidine is a substrate for CYP3A4 and P-glycoprotein (P-gp) and an inhibitor of CYP2D6 and P-gp; cobicistat is a substrate and inhibitor of both these enzymes and an inhibitor of P-gp. Concurrent use may result in elevated plasma concentration of both drugs. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as quinidine. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Diazepam: (Moderate) The plasma concentrations of diazepam may be elevated when administered concurrently with cobicistat. Close clinical monitoring is recommended during coadministration; diazepam dose reductions may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of diazepam. These drugs used in combination may result in elevated diazepam plasma concentrations, causing an increased risk for diazepam-related adverse events.
Dichlorphenamide: (Major) Use of dichlorphenamide and tenofovir disoproxil fumarate is not recommended because of increased tenofovir exposure and a risk of tenofovir-related adverse effects. Monitor closely for signs of drug toxicity if coadministration cannot be avoided. For example, it is important to monitor renal and hepatic function for all patients during treatment with tenofovir, as the drug may cause hepatotoxicity or nephrotoxicity. Increased tenofovir exposure is possible. Tenofovir is a sensitive OAT1 substrate. Dichlorphenamide inhibits OAT1.
Diclofenac: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Caution is warranted when cobicistat is administered with diclofenac as there is a potential for increased diclofenac concentrations. Diclofenac is a substrate of CYP3A4 and CYP2C9. Cobicistat is an inhibitor of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with diclofenac as there is a potential for decreased diclofenac concentrations. Diclofenac is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Diclofenac; Misoprostol: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Caution is warranted when cobicistat is administered with diclofenac as there is a potential for increased diclofenac concentrations. Diclofenac is a substrate of CYP3A4 and CYP2C9. Cobicistat is an inhibitor of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with diclofenac as there is a potential for decreased diclofenac concentrations. Diclofenac is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Didanosine, ddI: (Major) HIV guidelines recommend against concurrent use of tenofovir, PMPA and didanosine; however, these medications can be used together, if necessary, in patients with a creatinine clearance 60 mL/min or more if the didanosine dose is reduced; decrease the didanosine dose to 250 mg in patients weighing 60 kg or more and to 200 mg in patients weighing 25 to 59 kg. Concurrent administration of tenofovir, PMPA and didanosine, ddI increases the concentration of both didanosine and its active metabolite (dideoxyadenosine 5-triphosphate) which may cause or worsen didanosine-related clinical toxicities, including pancreatitis, symptomatic hyperlactatemia/lactic acidosis, and peripheral neuropathy. In addition, this combination has been associated with CD4 cell count decline despite viral suppression, high rates of early virologic failure, and rapid selection of resistance mutations. The mechanism of the interaction is not known, but the interaction occurs with both buffered and non-buffered didanosine formulations. When coadministered, tenofovir and didanosine EC may be taken under fasted conditions or with a light meal (under 400 kcal, containing 20% or less fat); coadministration of didanosine buffered tablet formulation with tenofovir should be under fasted conditions. Coadministration of tenofovir and didanosine should be undertaken with caution and patients receiving this combination should be monitored closely for didanosine-associated adverse events. Didanosine therapy should be suspended if signs or symptoms of pancreatitis, symptomatic hyperlactatemia, or lactic acidosis develop. (Moderate) Elvitegravir must be taken with food; didanosine, ddI must be taken on an empty stomach. If these drug are administered together, give didanosine on an empty stomach at least 1 hour before or 2 hours after adminstering elvitegravir with food.
Dienogest; Estradiol valerate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with dienogest. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Diflunisal: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Digoxin: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of digoxin with cobicistat. Digoxin is a substrate for P-gp; cobicistat is an inhibitor of this drug transporter. Concurrent use may result in elevated digoxin plasma concentration.
Dihydroergotamine: (Contraindicated) Concomitant use of ergotamine with cobicistat is contraindicated due to an increased risk for vasospasm which may lead to cerebral or peripheral ischemia. Concomitant use may increase ergotamine exposure. Ergotamine is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor.
Diltiazem: (Moderate) Monitor blood pressure and heart rate if coadministration of diltiazem with cobicistat is necessary. Diltiazem is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Diphenhydramine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Caution is warranted when elvitegravir is administered with diphenhydramine as there is a potential for decreased diphenhydramine concentrations. Diphenhydramine is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Diphenhydramine; Ibuprofen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Caution is warranted when elvitegravir is administered with diphenhydramine as there is a potential for decreased diphenhydramine concentrations. Diphenhydramine is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Diphenhydramine; Naproxen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Caution is warranted when elvitegravir is administered with diphenhydramine as there is a potential for decreased diphenhydramine concentrations. Diphenhydramine is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of naproxen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while naproxen is a CYP2C9 substrate.
Diphenhydramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Caution is warranted when elvitegravir is administered with diphenhydramine as there is a potential for decreased diphenhydramine concentrations. Diphenhydramine is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Disopyramide: (Major) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of disopyramide with cobicistat. Disopyramide is a substrate for CYP3A4; cobicistat is a strong inhibitor of this enzyme. Concurrent use may result in elevated disopyramide plasma concentration. Cases of life-threatening interactions have been reported for disopyramide when given with another strong CYP3A4 inhibitor.
Disulfiram: (Moderate) The plasma concentrations of disulfiram may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while disulfiram is a CYP3A4 substrate.
Docetaxel: (Major) Avoid coadministration of docetaxel with cobicistat if possible due to increased plasma concentrations of docetaxel. If concomitant use is unavoidable, closely monitor for docetaxel-related adverse reactions and consider a 50% dose reduction of docetaxel. Docetaxel is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Concomitant use with another strong CYP3A4 inhibitor increased docetaxel exposure by 2.2-fold.
Dofetilide: (Major) Dofetilide should be co-administered with tenofovir, PMPA with caution since both drugs are actively secreted via cationic secretion and could compete for common renal tubular transport systems. This results in a possible increase in plasma concentrations of either drug. Increased concentrations of dofetilide may increase the risk for side effects including proarrhythmia. Careful patient monitoring and dose adjustment of dofetilide is recommended. (Moderate) Use caution when administering dofetilide concurrently with emtricitabine as both drugs are actively secreted via cationic secretion and could compete for common renal tubular transport systems. This results in a possible increase in plasma concentrations of either drug. Increased concentrations of dofetilide may increase the risk for side effects including proarrhythmia.
Dolasetron: (Moderate) The plasma concentrations of hydrodolasetron (primary dolasetron metabolite) may be elevated when dolasetron is administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as headache or cardiovascular effects, is recommended during coadministration. Cobicistat is a CYP3A4 and CYP2D6 inhibitor, while hydrodolasetron is a CYP3A4 and CYP2D6 substrate.
Dolutegravir: (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp.
Dolutegravir; Lamivudine: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine. (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp.
Dolutegravir; Rilpivirine: (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp. (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
Donepezil: (Moderate) The plasma concentrations of donepezil may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or cholinergic effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor, while donepezil is a CYP3A4 and CYP2D6 substrate.
Donepezil; Memantine: (Moderate) The plasma concentrations of donepezil may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or cholinergic effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor, while donepezil is a CYP3A4 and CYP2D6 substrate.
Doravirine: (Minor) Coadministration of doravirine and cobicistat may result in increased doravirine plasma concentrations. Doravirine is a CYP3A4 substrate; cobicistat is a strong inhibitor. In drug interaction studies, concurrent use of strong CYP3A4 inhibitors increased doravirine exposure by more than 3-fold; however, this increase was not considered clinically significant.
Doravirine; Lamivudine; Tenofovir disoproxil fumarate: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine. (Minor) Coadministration of doravirine and cobicistat may result in increased doravirine plasma concentrations. Doravirine is a CYP3A4 substrate; cobicistat is a strong inhibitor. In drug interaction studies, concurrent use of strong CYP3A4 inhibitors increased doravirine exposure by more than 3-fold; however, this increase was not considered clinically significant.
Dorzolamide; Timolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as timolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
Doxazosin: (Moderate) Monitor blood pressure and for signs of hypotension during coadministration. The plasma concentrations of doxazosin may be elevated when administered concurrently with cobicistat. Cobicistat is a strong CYP3A4 inhibitor; doxazosin is a CYP3A4 substrate. Coadministration of doxazosin with a moderate CYP3A4 inhibitor resulted in a 10% increase in mean AUC and an insignificant increase in mean Cmax and mean half-life of doxazosin. Although not studied in combination with doxazosin, strong CYP3A4 inhibitors may have a larger impact on doxazosin concentrations and therefore should be used with caution.
Doxepin: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Doxorubicin Liposomal: (Major) Avoid coadministration of cobicistat and doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-glycoprotein (P-gp); doxorubicin is a major CYP2D6, CYP3A4, and P-gp substrate. Clinically significant interactions have been reported when doxorubicin was coadministered with inhibitors of CYP2D6, CYP3A4, and/or P-gp, resulting in increased concentration and clinical effect of doxorubicin.
Doxorubicin: (Major) Avoid coadministration of cobicistat and doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-glycoprotein (P-gp); doxorubicin is a major CYP2D6, CYP3A4, and P-gp substrate. Clinically significant interactions have been reported when doxorubicin was coadministered with inhibitors of CYP2D6, CYP3A4, and/or P-gp, resulting in increased concentration and clinical effect of doxorubicin.
Dronabinol: (Moderate) Use caution if coadministration of dronabinol with cobicistat is necessary, and closely monitor for an increase in dronabinol-related adverse reactions (e.g., cognitive impairment, psychosis, seizures, and hemodynamic instability, as well as feeling high, dizziness, confusion, somnolence). Concomitant use may result in elevated plasma concentrations of dronabinol. Cobicistat is a strong inhibitor of CYP3A4; dronabinol is a CYP2C9 and 3A4 substrate. (Moderate) Use caution if coadministration of dronabinol with elvitegravir is necessary, and monitor for a decrease in the efficacy of dronabinol. Dronabinol is a CYP2C9 and 3A4 substrate; elvitegravir is a moderate inducer of CYP2C9. Concomitant use may result in decreased plasma concentrations of dronabinol.
Dronedarone: (Contraindicated) Coadministration of cobicistat with dronedarone is contraindicated due to the potential for elevated dronedarone concentrations. Dronedarone is a CYP3A4 inhibitor/substrate and a CYP2D6 inhibitor. Cobicistat is an inhibitor/substrate of both CYP3A4 and CYP2D6. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as dronedarone. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Drospirenone: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Drospirenone; Estetrol: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Drospirenone; Estradiol: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Drospirenone; Ethinyl Estradiol: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Duloxetine: (Moderate) Caution is warranted when cobicistat is administered with duloxetine as there is a potential for elevated duloxetine and cobicistat concentrations. Duloxetine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Dutasteride: (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Dutasteride; Tamsulosin: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Duvelisib: (Major) Reduce duvelisib dose to 15 mg PO twice daily and monitor for increased toxicity when coadministered with cobicistat. Coadministration may increase the exposure of duvelisib. Duvelisib is a CYP3A substrate; cobicistat is a strong CYP3A inhibitor. The increase in exposure to duvelisib is estimated to be approximately 2-fold when used concomitantly with strong CYP3A inhibitors such as cobicistat.
Echinacea: (Moderate) Use Echinacea sp. with caution in patients taking medications for human immunodeficiency virus (HIV) infection. Some experts have suggested that Echinacea's effects on the immune system might cause problems for patients with HIV infection, particularly with long-term use. There may be less risk with short-term use (less than 2 weeks). A few pharmacokinetic studies have shown reductions in blood levels of some antiretroviral medications when Echinacea was given, presumably due to CYP induction. However, more study is needed for various HIV treatment regimens. Of the agents studied, the interactions do not appear to be significant or to require dose adjustments at the time of use. Although no dose adjustments are required, monitoring drug concentrations may give reassurance during co-administration. Monitor viral load and other parameters carefully during therapy.
Edoxaban: (Moderate) Coadministration of edoxaban and cobicistat may result in increased concentrations of edoxaban. Edoxaban is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor. Increased concentrations of edoxaban may occur during concomitant use of cobicistat; monitor for increased adverse effects of edoxaban. Dosage reduction may be considered for patients being treated for deep venous thrombosis (DVT) or pulmonary embolism.
Efavirenz: (Major) Avoid coadministration of elvitegravir with efavirenz or efavirenz; emtricitabine; tenofovir, as concurrent use is expected to decrease elvitegravir plasma concentrations. Efavirenz is a substrate and inducer of CYP3A4; elvitegravir is a CYP3A4 substrate. Use of these drugs together may result in loss of antiviral efficacy and potentially the development of viral resistance. (Major) Due to the potential for decreased antiretroviral efficacy, use of efavirenz with cobicistat and darunavir should be avoided. In addition, efavirenz is not recommended for use in combination with cobicistat and atazanavir in antiretroviral-experienced patients; however, this combination may be used in treatment-naive patients if the following dose recommendations are followed: cobicistat 150 mg PO and atazanavir 400 mg PO once daily with food, plus efavirenz 600 mg once daily on an empty stomach. When these drugs are given together, the concentrations of cobicistat, darunavir, and atazanavir are decreased. Efavirenz is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, and darunavir and atazanavir are CYP3A4 substrates.
Efavirenz; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) Avoid coadministration of elvitegravir with efavirenz or efavirenz; emtricitabine; tenofovir, as concurrent use is expected to decrease elvitegravir plasma concentrations. Efavirenz is a substrate and inducer of CYP3A4; elvitegravir is a CYP3A4 substrate. Use of these drugs together may result in loss of antiviral efficacy and potentially the development of viral resistance. (Major) Due to the potential for decreased antiretroviral efficacy, use of efavirenz with cobicistat and darunavir should be avoided. In addition, efavirenz is not recommended for use in combination with cobicistat and atazanavir in antiretroviral-experienced patients; however, this combination may be used in treatment-naive patients if the following dose recommendations are followed: cobicistat 150 mg PO and atazanavir 400 mg PO once daily with food, plus efavirenz 600 mg once daily on an empty stomach. When these drugs are given together, the concentrations of cobicistat, darunavir, and atazanavir are decreased. Efavirenz is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, and darunavir and atazanavir are CYP3A4 substrates.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Major) Avoid coadministration of elvitegravir with efavirenz or efavirenz; emtricitabine; tenofovir, as concurrent use is expected to decrease elvitegravir plasma concentrations. Efavirenz is a substrate and inducer of CYP3A4; elvitegravir is a CYP3A4 substrate. Use of these drugs together may result in loss of antiviral efficacy and potentially the development of viral resistance. (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine. (Major) Due to the potential for decreased antiretroviral efficacy, use of efavirenz with cobicistat and darunavir should be avoided. In addition, efavirenz is not recommended for use in combination with cobicistat and atazanavir in antiretroviral-experienced patients; however, this combination may be used in treatment-naive patients if the following dose recommendations are followed: cobicistat 150 mg PO and atazanavir 400 mg PO once daily with food, plus efavirenz 600 mg once daily on an empty stomach. When these drugs are given together, the concentrations of cobicistat, darunavir, and atazanavir are decreased. Efavirenz is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, and darunavir and atazanavir are CYP3A4 substrates.
Elacestrant: (Major) Avoid concomitant use of elacestrant and cobicistat due to the risk of increased elacestrant exposure which may increase the risk for adverse effects. Elacestrant is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use with another strong CYP3A inhibitor increased elacestrant overall exposure by 5.3-fold. (Moderate) Coadministration of tenofovir disoproxil fumarate with elacestrant may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is substrate of BCRP and P-gp; elacestrant is an inhibitor of BCRP and P-gp.
Elagolix: (Contraindicated) Concomitant use of elagolix and strong organic anion transporting polypeptide (OATP) 1B1 inhibitors such as cobicistat is contraindicated. Use of elagolix with drugs that inhibit OATP1B1 may increase elagolix plasma concentrations. Elagolix is a substrate of CYP3A, P-gp, and OATP1B1. Cobicistat is a combined inhibitor; it is a potent inhibitor of CYP3A and inhibits OATP1B1 and P-gp. Another OATP1B1 potent inhibitor increased elagolix AUC in the range of 2- to 5.58-fold. Increased elagolix concentrations increase the risk for dose-related side effects, including loss of bone mineral density.
Elagolix; Estradiol; Norethindrone acetate: (Contraindicated) Concomitant use of elagolix and strong organic anion transporting polypeptide (OATP) 1B1 inhibitors such as cobicistat is contraindicated. Use of elagolix with drugs that inhibit OATP1B1 may increase elagolix plasma concentrations. Elagolix is a substrate of CYP3A, P-gp, and OATP1B1. Cobicistat is a combined inhibitor; it is a potent inhibitor of CYP3A and inhibits OATP1B1 and P-gp. Another OATP1B1 potent inhibitor increased elagolix AUC in the range of 2- to 5.58-fold. Increased elagolix concentrations increase the risk for dose-related side effects, including loss of bone mineral density. (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Elbasvir; Grazoprevir: (Major) Concurrent administration of elbasvir with cobicistat is not recommended. Use of these drugs together is expected to significantly increase the plasma concentrations of elbasvir and may result in adverse effects (i.e., elevated ALT concentrations). Cobicistat is a strong inhibitor of the hepatic enzyme CYP3A, while elbasvir is metabolized by CYP3A. (Major) Concurrent administration of grazoprevir with cobicistat should be avoided if possible. Use of these drugs together is expected to significantly increase the plasma concentrations of grazoprevir and may result in adverse effects (i.e., elevated ALT concentrations). Cobicistat is an inhibitor of the hepatic enzyme CYP3A, while grazoprevir is metabolized by CYP3A.
Eletriptan: (Contraindicated) Eletriptan is contraindicated with recent use (i.e., within 72 hours) of cobicistat due to the potential for increased eletriptan exposure. Eletriptan is a sensitive substrate of CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the Cmax and AUC of eletriptan by 3-fold and 6-fold, respectively.
Elexacaftor; tezacaftor; ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Coadministration is not recommended in patients younger than 6 months. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. (Major) Reduce the dosing frequency of elexacaftor; tezacaftor; ivacaftor to twice a week in the morning, approximately 3 to 4 days apart (i.e., Day 1 and Day 4) when coadministered with cobicistat; omit the evening dose of ivacaftor. Coadministration may increase elexacaftor; tezacaftor; ivacaftor exposure and adverse reactions. Elexacaftor, tezacaftor, and ivacaftor are CYP3A substrates; cobicistat is a strong CYP3A inhibitor. Coadministration of a strong CYP3A inhibitor increased elexacaftor exposure by 2.8- fold, tezacaftor exposure by 4.5-fold, and ivacaftor exposure by 15.6-fold. (Major) Reduce the dosing frequency of tezacaftor; ivacaftor when coadministered with cobicistat; coadministration may increase tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 1 tezacaftor/ivacaftor combination tablet twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate); cobicistat is a strong CYP3A inhibitor. Coadministration of a strong CYP3A inhibitor increased tezacaftor and ivacaftor exposure 4- and 15.6-fold, respectively. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as ivacaftor. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Eliglustat: (Major) Coadministration of eliglustat and cobicistat is contraindicated in intermediate or poor CYP2D6 metabolizers (IMs or PMs). In extensive CYP2D6 metabolizers (EMs), coadministration of these agents requires dosage reduction of eliglustat to 84 mg PO once daily. The coadministration of eliglustat with cobicistat and a moderate or strong CYP2D6 inhibitor is contraindicated in all patients. Eliglustat is a CYP3A and CYP2D6 substrate. Coadministration of eliglustat with CYP3A inhibitors, such as cobicistat, increases eliglustat exposure and the risk of serious adverse events (e.g., QT prolongation and cardiac arrhythmias); this risk is the highest in CYP2D6 IMs and PMs because a larger portion of the eliglustat dose is metabolized via CYP3A. The product labeling for cobicistat states that coadministration of other drugs for which altered plasma concentrations are associated with serious and/or life-threatening effects is contraindicated; however, the interaction between ketoconazole (another potent CYP3A inhibitor) and eliglustat was studied during clinical trials. The resultant data supports eliglustat dosage reduction in EMs instead of contraindication. (Moderate) Coadministration of tenofovir, PMPA and eliglustat may result in increased concentrations of tenofovir. Monitor patients closely for tenofovir-related adverse effects including nausea, diarrhea, headache, asthenia, and nephrotoxicity. Tenofovir is a P-glycoprotein (P-gp) substrate; eliglustat is a P-gp inhibitor. For coadministration with P-gp substrates, eliglustat's product labeling recommends monitoring therapeutic drug concentrations of the P-gp substrate, if possible, or consideration of a dosage reduction and titrating to clinical effect.
Eluxadoline: (Major) When administered concurrently with cobicistat, the dose of eluxadoline must be reduced to 75 mg PO twice daily, and the patient should be closely monitored for eluxadoline-related adverse effects (i.e., decreased mental and physical acuity). Eluxadoline is a substrate of the organic anion-transporting peptide (OATP1B1); cobicistat is an OATP1B1/1B3 inhibitor. Advise patients against driving or operating machinery until the combine effects of these drugs on the individual patient is known.
Empagliflozin; Linagliptin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Empagliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
Emtricitabine; Rilpivirine; Tenofovir Disoproxil Fumarate: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
Enasidenib: (Moderate) Coadministration of tenofovir disoproxil fumarate with enasidenib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and enasidenib is a P-gp and BCRP inhibitor.
Encorafenib: (Major) Avoid coadministration of encorafenib and cobicistat due to increased encorafenib exposure. If concurrent use cannot be avoided, reduce the encorafenib dose to one-third of the dose used prior to the addition of cobicistat. If cobicistat is discontinued, the original encorafenib dose may be resumed after 3 to 5 elimination half-lives of cobicistat. Encorafenib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 50 mg dose of encorafenib (0.1 times the recommended dose) increased the encorafenib AUC and Cmax by 3-fold and 68%, respectively. (Moderate) Coadministration of tenofovir disoproxil fumarate with encorafenib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a BCRP substrate and encorafenib is a BCRP inhibitor.
Enfortumab vedotin: (Moderate) Closely monitor for signs of enfortumab vedotin-related adverse reactions if concurrent use with cobicistat is necessary. Concomitant use may increase unconjugated monomethyl auristatin E (MMAE) exposure, which may increase the incidence or severity of enfortumab-vedotin toxicities. MMAE, the microtubule-disrupting component of enfortumab vedotin, is a CYP3A4 and P-gp substrate; cobicistat is a dual P-gp/strong CYP3A4 inhibitor. Based on physiologically-based pharmacokinetic (PBPK) modeling predictions, concomitant use of enfortumab vedotin with another dual P-gp/strong CYP3A4 inhibitor is predicted to increase the exposure of unconjugated MMAE by 38%.
Entrectinib: (Major) Avoid coadministration of entrectinib with cobicistat due to increased entrectinib exposure resulting in increased treatment-related adverse effects. If coadministration cannot be avoided in adults and pediatric patients 12 years and older with BSA greater than 1.5 m2, reduce the entrectinib dose to 100 mg PO once daily. If cobicistat is discontinued, resume the original entrectinib dose after 3 to 5 elimination half-lives of cobicistat. Entrectinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the AUC of entrectinib by 6-fold in a drug interaction study.
Enzalutamide: (Major) Coadministration of cobicistat with enzalutamide is not recommended as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is metabolized by CYP3A4; enzalutamide is a strong CYP3A4 inducer. (Major) Coadministration of elvitegravir with enzalutamide is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is metabolized by CYP3A4; enzalutamide is a strong CYP3A4 inducer.
Eplerenone: (Contraindicated) Eplerenone is contraindicated for use with cobicistat due to increased eplerenone exposure which increases the risk of developing hyperkalemia and hypotension. Cobicitat is a strong CYP3A4 inhibitor; eplerenone is a sensitive CYP3A4 substrate. Another strong CYP3A4 inhibitor increased serum eplerenone concentrations by roughly 5-fold.
Erdafitinib: (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Ergotamine: (Contraindicated) Concomitant use of ergotamine with cobicistat is contraindicated due to an increased risk for vasospasm which may lead to cerebral or peripheral ischemia. Concomitant use may increase ergotamine exposure. Ergotamine is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor.
Ergotamine; Caffeine: (Contraindicated) Concomitant use of ergotamine with cobicistat is contraindicated due to an increased risk for vasospasm which may lead to cerebral or peripheral ischemia. Concomitant use may increase ergotamine exposure. Ergotamine is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor.
Erlotinib: (Major) Avoid coadministration of erlotinib with cobicistat if possible due to the increased risk of erlotinib-related adverse reactions. If concomitant use is unavoidable and severe reactions occur, reduce the dose of erlotinib by 50 mg decrements. Erlotinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased erlotinib exposure by 67%.
Ertugliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Erythromycin: (Major) Avoid concurrent use of erythromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of erythromycin, cobicistat, atazanavir and darunavir. Erythromycin is a CYP3A4 inhibitor and a P-glycoprotein (P-gp) substrate. Cobicistat is a substrate of CYP3A4 and a P-gp inhibitor, while both atazanavir and darunavir are CYP3A4 substrates. (Moderate) Coadministration of tenofovir disoproxil fumarate with erythromycin may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and erythromycin is a P-gp inhibitor.
Escitalopram: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Eslicarbazepine: (Major) In vivo studies suggest eslicarbazepine is an inducer of CYP3A4. Coadministration may result in significant decreases in the plasma concentrations of the CYP3A4 substrates, cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Consider use of an alternative anticonvulsant. (Major) In vivo studies suggest eslicarbazepine is an inducer of CYP3A4. Coadministration of elvitegravir, may result in significant decreases in the plasma concentrations of the CYP3A4 substrate, elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Consider use of an alternative anticonvulsant.
Esomeprazole: (Minor) Use caution when administering cobicistat and esomeprazole concurrently. Cobicistat is an inhibitor of CYP3A, and esomeprazole is partially metabolized by CYP3A. Coadministration of cobicistat with CYP3A substrates, such as esomeprazole, can theoretically increase esomeprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
Estazolam: (Moderate) The plasma concentrations of estazolam may be elevated when administered concurrently with cobicistat. Close clinical monitoring is recommended during coadministration; estazolam dose reductions may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of estazolam. These drugs used in combination may result in elevated estazolam plasma concentrations, causing an increased risk for estazolam-related adverse events.
Estradiol; Levonorgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Estradiol; Norethindrone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Estradiol; Norgestimate: (Major) Concurrent administration of cobicistat and norgestimate results in increased norgestimate serum concentrations. Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is also the potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Estradiol; Progesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with progesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. The metabolism of progesterone may also be inhibited by cobicistat, a strong inhibitor of the CYP3A4 hepatic enzyme. This interaction does not apply to vaginal preparations of progesterone (e.g., Crinone, Endometrin).
Eszopiclone: (Major) The total dose of eszopiclone should not exceed 2 mg when administered with cobicistat. Coadministration may increase eszopiclone exposure resulting in increased risk of next-day psychomotor or memory impairment and decreased ability to perform tasks requiring full mental alertness such as driving. CYP3A4 is a primary metabolic pathway for eszopiclone; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased eszopiclone exposure by 2.2-fold.
Ethinyl Estradiol; Norelgestromin: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norelgestromin. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Ethinyl Estradiol; Norethindrone Acetate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Ethinyl Estradiol; Norgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Ethiodized Oil: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Ethosuximide: (Moderate) Close clinical monitoring is advised when administering ethosuximide with cobicistat. Coadministration may result in elevated ethosuximide plasma concentrations. Predictions regarding this interaction may be made based on the metabolic pathway of both drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of ethosuximide.
Ethynodiol Diacetate; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with ethynodiol diacetate. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Etodolac: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Etonogestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with etonogestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
Etonogestrel; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with etonogestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Etravirine: (Major) Due to the potential for decreased antiretroviral efficacy and potential for adverse events, use of etravirine with cobicistat is not recommended. When these drugs are given together, the concentrations of cobicistat and etravirine may be decreased and increased, respectively. Both drugs are substrates for CYP3A4. Etravirine is also a CYP3A4 inducer, while cobicistat is a strong CYP3A4 inhibitor. Coadministration of etravirine with another strong CYP3A4 inhibitor increased etravirine exposure by 1.42-fold. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as etravirine. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Everolimus: (Major) Avoid coadministration of everolimus with cobicistat due to the risk of increased everolimus-related adverse reactions. If concomitant use is unavoidable in patients receiving everolimus for either kidney or liver transplant, closely monitor everolimus whole blood trough concentrations. Everolimus is a sensitive CYP3A4 substrate and a P-glycoprotein (P-gp) substrate. Cobicistat is a strong CYP3A4 and P-gp inhibitor. Coadministration with another strong CYP3A4/P-gp inhibitor increased the AUC of everolimus by 15-fold.
Ezetimibe; Simvastatin: (Contraindicated) Concomitant use of simvastatin with cobicistat is contraindicated due to increased simvastatin exposure and potential for myopathy, including rhabdomyolysis. Simvastatin is a substrate for CYP3A4; cobicistat is a strong CYP3A4 inhibitor.
Fedratinib: (Major) Avoid coadministration of fedratinib with cobicistat as concurrent use may increase fedratinib exposure. If concurrent use cannot be avoided, reduce the dose of fedratinib to 200 mg PO once daily. If cobicistat is discontinued, increase the fedratinib dose as follows: 300 mg PO once daily for 2 weeks and then 400 mg PO once daily thereafter as tolerated. Fedratinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased fedratinib exposure by 3-fold.
Felbamate: (Major) Coadministration of felbamate with cobicistat is not recommended. Concurrent use may decrease the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Felbamate is a CYP3A4 inducer, while cobicistat is a substrate of CYP3A4. (Major) Coadministration of felbamate with elvitegravir is not recommended. Concurrent use may decrease the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Felbamate is a CYP3A4 inducer, while elvitegravir is a substrate of CYP3A4.
Felodipine: (Moderate) Concurrent use of felodipine and cobicistat should be approached with caution and conservative dosing of felodipine due to the potential for significant increases in felodipine exposure. Monitor for evidence of increased felodipine effects including decreased blood pressure and increased heart rate. Felodipine is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Concurrent use of another strong CYP3A4 inhibitor increased felodipine AUC and half-life by approximately 8-fold and 2-fold, respectively.
Fenoprofen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Fentanyl: (Moderate) Consider a reduced dose of fentanyl with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the fentanyl dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Fentanyl is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like cobicistat can increase fentanyl exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of fentanyl. If cobicistat is discontinued, fentanyl plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to fentanyl.
Ferric Maltol: (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Fesoterodine: (Major) Limit the dose of fesoterodine to 4 mg once daily in adults and pediatric patients weighing more than 35 kg if coadministered with cobicistat. Avoid use of fesoterodine and cobicistat in pediatric patients weighing 25 to 35 kg. Concurrent use may increase fesoterodine exposure. Fesoterodine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor led to approximately a doubling of the overall exposure of 5-hydroxymethyl tolterodine (5-HMT), the active metabolite of fesoterodine.
Finasteride; Tadalafil: (Major) Avoid coadministration of tadalafil and cobicistat for the treatment of pulmonary hypertension. For the treatment of erectile dysfunction, do not exceed 10 mg tadalafil within 72 hours of cobicistat for the 'as needed' dose or 2.5 mg daily for the 'once-daily' dose. Tadalafil is metabolized predominantly by CYP3A. Potent inhibitors of CYP3A, such as cobicistat, may reduce tadalafil clearance. Increased systemic exposure to tadalafil may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection.
Finerenone: (Contraindicated) Concomitant use of finerenone and cobicistat is contraindicated. Concomitant use may increase finerenone exposure and the risk for finerenone-related adverse reactions. Finerenone is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased overall exposure to finerenone by more than 400%.
Flecainide: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of flecainide with cobicistat. Flecainide is a substrate for CYP2D6; cobicistat is an inhibitor of this enzyme. Concurrent use may result in elevated flecainde plasma concentration.
Flibanserin: (Contraindicated) The concomitant use of flibanserin and strong CYP3A4 inhibitors such as cobicistat is contraindicated due to increased flibanserin concentrations, which can cause severe hypotension and syncope. If initiating flibanserin following the use of cobicistat, start flibanserin at least 2 weeks after the last dose of cobicistat. If initiating cobicistat following flibanserin use, begin therapy at least 2 days after the last dose of flibanserin. In cases where the benefit of initiating cobicistat therapy within 2 days of stopping flibanserin clearly outweighs the risk of flibanserin-related hypotension and syncope, monitor the patient for signs of hypotension and syncope.
Fluconazole: (Moderate) Caution is warranted when cobicistat is administered with fluconazole as there is a potential for elevated cobicistat concentrations. Fluconazole is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with fluconazole as there is a potential for elevated elvitegravir concentrations. Fluconazole is a CYP3A4 and CYP2D6 inhibitor, while elvitegravir is a substrate of CYP3A4.
Fluoxetine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Fluphenazine: (Moderate) Caution is warranted when cobicistat is administered with fluphenazine as there is a potential for elevated concentrations of fluphenazine and cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Fluphenazine and cobicistat are substrates and inhibitors of CYP2D6.
Flurazepam: (Moderate) The plasma concentrations of flurazepam may be elevated when administered concurrently with cobicistat. Close clinical monitoring is recommended during coadministration; flurazepam dose reductions may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4; inhibitors of this isoenzyme may reduce the metabolism of flurazepam and increase the potential for benzodiazepine toxicity.
Flurbiprofen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of flurbiprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while flurbiprofen is a CYP2C9 substrate.
Flutamide: (Major) Caution is warranted when cobicistat is administered with flutamide as there is a potential for elevated flutamide concentrations and decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Flutamide is a substrate and inducer of CYP3A4. Cobicistat is a CYP3A4 substrate and inhibitor. (Major) Caution is warranted when elvitegravir is administered with flutamide as there is a potential for decreased concentrations of elvitegravir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Flutamide is a substrate and inducer of CYP3A4. Elvitegravir is a CYP3A4 substrate.
Fluticasone: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate.
Fluticasone; Salmeterol: (Major) Avoid concomitant use of salmeterol with cobicistat. Concomitant use increases salmeterol exposure and may increase the incidence and severity of salmeterol-related adverse effects. Signs and symptoms of excessive beta-adrenergic stimulation commonly include tachyarrhythmias, hypertension, and tremor. Salmeterol is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased salmeterol overall exposure 16-fold mainly due to increased bioavailability of the swallowed portion of the dose. (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate.
Fluticasone; Umeclidinium; Vilanterol: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. (Moderate) Caution is warranted when cobicistat is administered with umeclidinium; vilanterol as there is a potential for elevated umeclidinium; vilanterol concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Umeclidinium; vilanterol is a substrate of CYP3A4, CYP2D6, and P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp inhibitor.
Fluticasone; Vilanterol: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. (Moderate) Caution is warranted when cobicistat is administered with umeclidinium; vilanterol as there is a potential for elevated umeclidinium; vilanterol concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Umeclidinium; vilanterol is a substrate of CYP3A4, CYP2D6, and P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp inhibitor.
Fluvastatin: (Major) The plasma concentrations of fluvastatin may increase when administered with cobicistat. Use the lowest starting dose of fluvastatin and carefully titrate while monitoring for adverse events.
Fluvoxamine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Folic Acid, Vitamin B9: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Food: (Major) Advise patients to avoid cannabis use during cobicistat treatment. Concomitant use may alter the exposure of some cannabinoids and increase the risk for adverse reactions. The cannabinoids delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are CYP3A substrates and cobicistat is a strong CYP3A inhibitor. Concomitant use of a cannabinoid product containing THC and CBD at an approximate 1:1 ratio with another strong CYP3A inhibitor increased THC, 11-OH-THC, and CBD peak exposures by 1.3-, 3-, and 1.9-fold respectively.
Formoterol; Mometasone: (Moderate) Coadministration of mometasone with cobicistat may cause elevated mometasone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Mometasone is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Fosamprenavir: (Major) Coadministration of cobicistat with fosamprenavir is not recommended because pharmacokinetic data are not available to provide appropriate dosing recommendations. Cobicistat is not interchangeable with ritonavir as a boosting agent to fosamprenavir. (Moderate) Coadministration of fosamprenavir boosted with ritonavir and elvitegravir results in an unknown effect on the plasma concentrations of elvitegravir. The recommended dosing regimen for these drugs used in combination is: elvitegravir 150 mg PO once daily with fosamprenavir/ritonavir 700/100 mg PO twice daily. No data are available for use of other doses.
Foscarnet: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as foscarnet. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and foscarnet are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Monitor for changes in serum creatinine and phosphorus if tenofovir is administered in combination with nephrotoxic agents, such as foscarnet. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir, and/or the co-administered drug. Drugs that decrease renal function may increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir; a majority of the cases occurred in patients who had underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir containing products should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Fosphenytoin: (Contraindicated) Coadministration of fosphenytoin with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy. (Major) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Fosphenytoin induces the CYP3A4 metabolism of elvitegravir. Consider an alternative anticonvulsant when using elvitegravir. The combination product cobicistat; elvitegravir; emtricitabine; tenofovir is contraindicated in combination with fosphenytoin as the concentrations of both elvitegravir and cobicistat may be significantly decreased.
Fostamatinib: (Moderate) Monitor for fostamatinib toxicities that may require fostamatinib dose reduction (i.e., elevated hepatic enzymes, neutropenia, high blood pressure, severe diarrhea) if given concurrently with a strong CYP3A4 inhibitor. Concomitant use of fostamatinib with a strong CYP3A4 inhibitor increases exposure to the major active metabolite, R406, which may increase the risk of adverse reactions. R406 is extensively metabolized by CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration of fostamatinib with another strong CYP3A4 inhibitor increased R406 AUC by 102% and Cmax by 37%. (Moderate) Monitor for tenofovir toxicities that may require tenofovir disoproxil dose reduction if given concurrently with fostamatinib. Concomitant use of fostamatinib with a BCRP or P-gp substrate may increase the concentration of the BCRP or P-gp substrate. Fostamatinib is a P-gp inhibitor, and the active metabolite of fostamatinib, R406, is a BCRP inhibitor; tenofovir disoproxil is a substrate for BCRP and P-gp. Coadministration of fostamatinib with another BCRP substrate increased the substrate AUC by 95% and Cmax by 88%. Coadministration of fostamatinib with another P-gp substrate increased the substrate AUC by 37% and Cmax by 70%.
Futibatinib: (Major) Avoid concurrent use of futibatinib and cobicistat. Concomitant use may increase futibatinib exposure and the risk of adverse effects (e.g., ocular toxicity, hyperphosphatemia). Futibatinib is a substrate of CYP3A and P-gp; cobicistat is a dual P-gp and strong CYP3A inhibitor. Coadministration with another dual P-gp and strong CYP3A inhibitor increased futibatinib exposure by 41%. (Moderate) Coadministration of tenofovir disoproxil fumarate with futibatinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and futibatinib is a P-gp and BCRP inhibitor.
Ganciclovir: (Moderate) Concurrent use of nephrotoxic agents with ganciclovir should be done cautiously to avoid additive nephrotoxicity. Other nephrotoxic agents include tenofovir. (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as ganciclovir. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and ganciclovir are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs.
Gefitinib: (Moderate) Monitor for an increase in gefitinib-related adverse reactions if coadministration with cobicistat is necessary. Gefitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased gefitinib exposure by 80%.
Gentamicin: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as aminoglycosides. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and aminoglycosides are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Gilteritinib: (Major) Consider an alternative to cobicistat during treatment with gilteritinib. Concurrent use may increase gilteritinib exposure resulting in treatment-related adverse events. If coadministration is required, frequently monitor for gilteritinib adverse reactions. Interrupt therapy and reduce the gilteritinib dose if serious or life-threatening toxicity occurs. Gilteritinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the gilteritinib AUC by 120% in a drug interaction study. (Moderate) Coadministration of tenofovir disoproxil fumarate with gilteritinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a substrate of P-gp and BCRP and gilteritinib is a P-gp and BCRP inhibitor.
Glasdegib: (Major) Consider an alternative to cobicistat during treatment with glasdegib. Concurrent use may increase glasdegib exposure resulting in treatment-related adverse events including QT prolongation. If coadministration cannot be avoided, monitor for increased adverse events; more frequent ECG monitoring is recommended. Glasdegib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the glasdegib AUC by 2.4-fold in a drug interaction study.
Glecaprevir; Pibrentasvir: (Moderate) Caution is advised with the coadministration of glecaprevir and cobicistat as coadministration may increase serum concentrations of glecaprevir and increase the risk of adverse effects. Glecaprevir is a substrate of P-glycoprotein (P-gp), organic anion transporting polypeptide (OATP) 1B1/3, and breast cancer resistance protein (BCRP); cobicistat is an inhibitor of all these transporters. (Moderate) Caution is advised with the coadministration of pibrentasvir and cobicistat as coadministration may increase serum concentrations of pibrentasvir and increase the risk of adverse effects. Pibrentasvir is a substrate of of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP); cobicistat is an inhibitor of P-gp and BCRP.
Glimepiride: (Minor) Plasma concentrations of glimepiride may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased hypoglycemic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while glimepiride is a CYP2C9 substrate.
Glipizide: (Minor) Plasma concentrations of glipizide may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased hypoglycemic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while glipizide is a CYP2C9 substrate.
Glipizide; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed. (Minor) Plasma concentrations of glipizide may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased hypoglycemic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while glipizide is a CYP2C9 substrate.
Glyburide: (Moderate) Caution is warranted when cobicistat is administered with glyburide as there is a potential for elevated glyburide concentrations. Glyburide is a substrate of P-glycoprotein (P-gp) and cobicistat is an inhibitor of P-gp. (Minor) Caution is warranted when elvitegravir is administered with glyburide as there is a potential for decreased glyburide concentrations. Patients may experience a decreased hypoglycemic effect during coadministration. Glyburide is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Glyburide; Metformin: (Moderate) Caution is warranted when cobicistat is administered with glyburide as there is a potential for elevated glyburide concentrations. Glyburide is a substrate of P-glycoprotein (P-gp) and cobicistat is an inhibitor of P-gp. (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed. (Minor) Caution is warranted when elvitegravir is administered with glyburide as there is a potential for decreased glyburide concentrations. Patients may experience a decreased hypoglycemic effect during coadministration. Glyburide is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Granisetron: (Minor) Plasma concentrations of granisetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or CNS effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while granisetron is a CYP3A4 substrate.
Grapefruit juice: (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as grapefruit juice. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Moderate) Caution is warranted when cobicistat is administered with grapefruit juice as there is a potential for elevated cobicistat concentrations. Grapefruit juice is a CYP3A4 and CYP2D6 inhibitor, while cobicistat is a substrate of CYP3A4 and CYP2D6.
Guaifenesin; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
Guanfacine: (Major) If coadministration of cobicistat with extended-release (ER) guanfacine is necessary, reduce the guanfacine dosage to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available. Monitor patients closely for alpha-adrenergic effects including hypotension, drowsiness, lethargy, and bradycardia. If cobicistat is discontinued, the guanfacine ER dosage should be increased back to the recommended dose. Guanfacine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Cobicistat may significantly increase guanfacine plasma concentrations.
Haloperidol: (Moderate) Caution is warranted when cobicistat is administered with haloperidol as there is a potential for elevated haloperidol concentrations. Haloperidol is a CYP3A4 substrate and CYP2D6 substrate. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6.
Homatropine; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
Hydrocodone; Ibuprofen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
Hydroxyprogesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with hydroxyprogesterone caproate. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Ibrexafungerp: (Major) Decrease the ibrexafungerp dose to 150 mg PO every 12 hours for 1 day if administered concurrently with cobicistat. Coadministration may result in increased ibrexafungerp exposure and toxicity. Ibrexafungerp is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the AUC and Cmax of ibrexafungerp by 5.8-fold and 2.5-fold, respectively.
Ibrutinib: (Major) Avoid concomitant use of ibrutinib and cobicistat; ibrutinib plasma concentrations may increase resulting in severe ibrutinib toxicity (e.g., hematologic toxicity, bleeding, infection). Ibrutinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased ibrutinib exposure by 5.7-fold to 24-fold.
Ibuprofen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Ibuprofen; Famotidine: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Ibuprofen; Oxycodone: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Ibuprofen; Pseudoephedrine: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of ibuprofen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while ibuprofen is a CYP2C9 substrate.
Idelalisib: (Major) Coadministration of idelalisib with cobicistat may increase the exposure of both drugs; avoid use and use alternative agents if possible. Both drugs are CYP3A4 substrates and strong CYP3A4 inhibitors. If use of both drugs is required, monitor for idelalisib- and cobicistat-related adverse reactions. Coadministration with a strong CYP3A inhibitor increased idelalisib expoure by 1.8-fold.
Ifosfamide: (Moderate) Monitor for a decrease in the efficacy of ifosfamide if coadministration with cobicistat is necessary. Ifosfamide is metabolized by CYP3A4 to its active alkylating metabolites. Cobicistat is a strong CYP3A4 inhibitor. Coadministration may decrease plasma concentrations of these active metabolites, decreasing the effectiveness of ifosfamide treatment.
Iloperidone: (Major) Reduce the iloperidone dose by one-half if coadministered with cobicistat If chloramphenicol is discontinued, increase the iloperidone dose to the previous level. Increased iloperidone exposure may occur with concurrent use. Iloperidone is a CYP3A4 substrate. Chloramphenicol is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the AUC of iloperidone and its metabolites P88 and P95 by 57%, 55% and 35%, respectively.
Imatinib: (Moderate) Caution is warranted when cobicistat is administered with imatinib, STI-571 as there is a potential for elevated imatinib and/or cobicistat concentrations. Imatinib is a CYP3A4 substrate and moderate iinhibitor, a weak inhibitor of CYP2D6, and a breast cancer resistance protein (BCRP) substrate. Cobicistat is a strong inhibitor of CYP3A4, a BCRP inhibitor, and a substrate of CYP2D6 and CYP3A4. Coadministration of imatinib with another strong CYP3A4 inhibitor increased imatinib exposure by 40%.
Imipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Indacaterol: (Moderate) Clinical monitoring for adverse effects, such as headache, nervousness, tremor, or cardiovascular effects, is recommended during coadministration. Plasma concentrations of indacaterol may be elevated when administered concurrently with cobicistat. Cobicistat is a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) inhibitor, while indacaterol is a CYP3A4, CYP2D6, and P-gp substrate. Coadministration with other dual inhibitors of CYP3A4 and P-gp has increased exposure of indacaterol from 1.4- to 1.9- fold.
Indacaterol; Glycopyrrolate: (Moderate) Clinical monitoring for adverse effects, such as headache, nervousness, tremor, or cardiovascular effects, is recommended during coadministration. Plasma concentrations of indacaterol may be elevated when administered concurrently with cobicistat. Cobicistat is a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) inhibitor, while indacaterol is a CYP3A4, CYP2D6, and P-gp substrate. Coadministration with other dual inhibitors of CYP3A4 and P-gp has increased exposure of indacaterol from 1.4- to 1.9- fold.
Indinavir: (Contraindicated) Concomitant use of indinavir with regimens containing cobicistat and atazanavir is contraindicated. Cobicistat is an inhibitor of CYP3A4, while both atazanavir and indinavir are CYP3A4 substates. In addition, both atazanavir and indinavir are associated with indirect (unconjugated) hyperbilirubinemia. Taking these drugs together may increase the risk for hepatic adverse events, such as hyperbilirubinemia. (Major) Avoid coadministration of indinavir with elvitegravir. No data are available regarding use of these drugs concurrently.
Indomethacin: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of indomethacin may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while indomethacin is a CYP2C9 substrate.
Infigratinib: (Major) Avoid concomitant use of infigratinib and cobicistat. Coadministration may increase infigratinib exposure, increasing the risk for adverse effects. Infigratinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the AUC of infigratinib by 622%.
Interferons: (Moderate) Use together with caution and monitor for hepatic decompensation. Interferons and anti-retroviral nucleoside reverse transcriptase inhibitors (NRTIs) can both cause hepatotoxicity. Patients with chronic, cirrhotic HCV co-infected with HIV receiving NRTIs and alpha interferons appear to be at increased risk for hepatic decompensation (e.g., Childs-Pugh score 6 or more) compared to patients not receiving HAART.
Iodixanol: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Iohexol: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Iomeprol: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Iopamidol: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Iopromide: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Ioversol: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Irinotecan Liposomal: (Major) Avoid administration of cobicistat during treatment with irinotecan and for at least 1 week prior to starting therapy unless there are no therapeutic alternatives. Coadministration is contraindicated if cobicistat is boosted with atazanavir. Irinotecan is a CYP3A4 substrate and its active metabolite, SN-38, is a substrate of UGT1A1. Cobicistat is a UGT1A1 inhibitor and a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 and UGT1A1 inhibitor increased exposure to both irinotecan and its active metabolite, SN-38.
Irinotecan: (Major) Avoid administration of cobicistat during treatment with irinotecan and for at least 1 week prior to starting therapy unless there are no therapeutic alternatives. Coadministration is contraindicated if cobicistat is boosted with atazanavir. Irinotecan is a CYP3A4 substrate and its active metabolite, SN-38, is a substrate of UGT1A1. Cobicistat is a UGT1A1 inhibitor and a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 and UGT1A1 inhibitor increased exposure to both irinotecan and its active metabolite, SN-38.
Iron Salts: (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Iron: (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Isavuconazonium: (Contraindicated) Coadministration of isavuconazonium with cobicistat is contraindicated due to the risk of increased isavuconazole exposure. Isavuconazole is a sensitive substrate of CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased isavuconazole exposure by 422%. (Moderate) Concomitant use of isavuconazonium with elvitegravir may result in increased concentrations of elvitegravir. Isavuconazole, the active moiety of isavuconazonium, is a moderate inhibitor of the hepatic isoenzyme CYP3A4; elvitegravir is a substrate of this enzyme. Caution and close monitoring are advised if these drugs are used together.
Isoniazid, INH: (Moderate) Caution is warranted when cobicistat is administered with isoniazid, INH as there is a potential for elevated cobicistat concentrations. Isoniazid is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Contraindicated) Coadministration of rifampin with cobicistat is contraindicated. Rifampin induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Coadministration of rifampin, a potent CYP3A4 inducer, with elvitegravir, a CYP3A4 substrate, is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Moderate) Caution is warranted when cobicistat is administered with isoniazid, INH as there is a potential for elevated cobicistat concentrations. Isoniazid is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4.
Isoniazid, INH; Rifampin: (Contraindicated) Coadministration of rifampin with cobicistat is contraindicated. Rifampin induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Coadministration of rifampin, a potent CYP3A4 inducer, with elvitegravir, a CYP3A4 substrate, is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Moderate) Caution is warranted when cobicistat is administered with isoniazid, INH as there is a potential for elevated cobicistat concentrations. Isoniazid is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4.
Isosulfan Blue: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Isradipine: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as isradipine, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate reductions are advised.
Istradefylline: (Major) Do not exceed 20 mg once daily of istradefylline if administered with cobicistat as istradefylline exposure and adverse effects may increase. Cobicistat is a strong CYP3A4 inhibitor. Istradefylline exposure was increased by 2.5-fold when administered with a strong inhibitor in a drug interaction study. (Moderate) Monitor for an increase in tenofovir-related adverse reactions if coadministration with istradefylline is necessary as concurrent use may increase tenofovir exposure. Tenofovir is a P-gp substrate and istradefylline is a P-gp inhibitor.
Itraconazole: (Major) Avoid concurrent use of itraconazole with regimens containing cobicistat and atazanavir or darunavir. Use of these drugs together may result in increased plasma concentrations of itraconazole, cobicistat, atazanavir, and darunavir. Specific dosage recommendations have not been determined. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as itraconazole. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Moderate) Monitor for evidence of elvitegravir-related adverse reactions if coadministration is necessary. Itraconazole is a strong CYP3A4 inhibitor; elvitegravir is a CYP3A4 substrate.
Ivabradine: (Contraindicated) Coadministration of cobicistat with ivabradine is contraindicated due to an increase in plasma concentrations of ivabradine, which may exacerbate bradycardia and conduction disturbances. Ivabradine is primarily metabolized by CYP3A4; cobicistat is a strong inhibitor of CYP3A4. Coadministration with another strong CYP3A4 inhibitor increased ivabradine exposure by 7.7-fold.
Ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Coadministration is not recommended in patients younger than 6 months. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as ivacaftor. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Ivosidenib: (Major) Avoid coadministration of ivosidenib with cobicistat due to increased plasma concentrations of ivosidenib, which increases the risk of QT prolongation. If concomitant use is unavoidable, reduce the dose of ivosidenib to 250 mg PO once daily. Monitor ECGs for QTc prolongation and monitor electrolytes, correcting any electrolyte abnormalities as clinically appropriate. If cobicistat is discontinued, wait at least 5 half-lives of cobicistat before increasing the dose of ivosidenib to the recommended dose of 500 mg PO once daily. Ivosidenib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ivosidenib single-dose AUC to 269% of control, with no change in Cmax.
Ixabepilone: (Major) Avoid concurrent use of ixabepilone and cobicistat due to increased ixabepilone exposure, which may increase the risk of adverse reactions. If concomitant use is unavoidable, reduce the dose of ixabepilone to 20 mg/m2. Ixabepilone is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ixabepilone exposure by 79%.
Ketoconazole: (Major) Avoid cobicistat for 2 weeks prior to and during treatment with ketoconazole. Concomitant use may increase exposure of both drugs and increase the risk of adverse effects. If concomitant use is necessary, monitor closely for adverse reactions; a ketoconazole dose reduction may be necessary. Both ketoconazole and cobicistat are CYP3A substrates and strong CYP3A inhibitors. (Major) Coadministration of ketoconazole with elvitegravir may result in increased plasma concentrations of both drugs. During concurrent use, a maximum ketoconazole dose of 200 mg/day is recommended. (Moderate) Monitor for an increase in tenofovir-related adverse effects if coadministration with ketoconazole is necessary. Concurrent use may increase tenofovir exposure. Tenofovir disoproxil fumarate is a P-gp substrate and ketoconazole is a P-gp inhibitor.
Ketoprofen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Ketorolac: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Lamivudine, 3TC: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine.
Lamivudine, 3TC; Zidovudine, ZDV: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine.
Lamivudine; Tenofovir Disoproxil Fumarate: (Major) Do not coadminister lamivudine, 3TC-containing products and emtricitabine-containing products due to similarities between emtricitabine and lamivudine.
Lansoprazole: (Minor) Use caution when administering cobicistat and lansoprazole concurrently. Cobicistat is an inhibitor of CYP3A. Coadministration of cobicistat with CYP3A substrates, such as lansoprazole, can increase lansoprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
Lansoprazole; Amoxicillin; Clarithromycin: (Major) Avoid concurrent use of clarithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of clarithromycin, cobicistat, atazanavir and darunavir. Both clarithromycin and cobicistat are inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as clarithromycin. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Minor) Use caution when administering cobicistat and lansoprazole concurrently. Cobicistat is an inhibitor of CYP3A. Coadministration of cobicistat with CYP3A substrates, such as lansoprazole, can increase lansoprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
Lapatinib: (Major) Avoid coadministration of lapatinib with cobicistat due to increased plasma concentrations of lapatinib. If concomitant use is unavoidable, decrease the dose of lapatinib to 500 mg PO once daily. If cobicistat is discontinued, increase lapatinib to the indicated dose after a washout period of approximately 1 week. Lapatinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Concomitant use with another strong CYP3A4 inhibitor increased lapatinib exposure by 3.6-fold and increased the half-life of lapatinib by 1.7-fold. (Moderate) Monitor for an increase in tenofovir-related adverse reactions if coadministration with lapatinib is necessary. Tenofovir is a P-glycoprotein (P-gp) substrate and lapatinib is a P-gp inhibitor. Increased plasma concentrations of tenofovir may occur.
Larotrectinib: (Major) Avoid coadministration of larotrectinib with cobicistat due to increased larotrectinib exposure resulting in increased treatment-related adverse effects. If coadministration cannot be avoided, reduce the larotrectinib dose by 50%. If cobicistat is discontinued, resume the original larotrectinib dose after 3 to 5 elimination half-lives of cobicistat. Larotrectinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the AUC of larotrectinib by 4.3-fold in a drug interaction study.
Lasmiditan: (Moderate) Coadministration of tenofovir disoproxil fumarate with lasmiditan may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and lasmiditan is a P-gp inhibitor.
Ledipasvir; Sofosbuvir: (Moderate) Caution is warranted when cobicistat is administered with ledipasvir; sofosbuvir as there is a potential for elevated concentrations of ledipasvir and sofosbuvir. Cobicistat is an inhibitor of the transporters P-glycoprotein and breast cancer resistance protein (BCRP). Both ledipasvir and sofosbuvir are substrates of P-gp and BCRP. According to the manufacturer, no dosage adjustments are required when ledipasvir; sofosbuvir is administered concurrently with P-gp or BCRP inhibitors; however, if these drugs are given together, consider increased monitoring for potential adverse effect. (Moderate) Closely monitor for tenofovir-associated adverse reactions if ledipasvir is administered with tenofovir disoproxil fumarate. In addition, because safety has not been established, avoid use of ledipasvir in combination with HIV regimens that contain tenofovir disoproxil fumarate and HIV protease inhibitors boosted with ritonavir. Consider use of tenofovir alafenamide in place of tenofovir disoproxil fumarate. If coadministration is deemed necessary, closely monitor for tenofovir adverse effects. Plasma concentrations of tenofovir may increase when administered with ledipasvir. Tenofovir is a substrate of the drug transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP); ledipasvir is an inhibitor of both P-gp and BCRP. (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP.
Lefamulin: (Major) Avoid coadministration of cobicistat with oral lefamulin due to increased lefamulin exposure; cobicistat may be administered with intravenous lefamulin. Lefamulin is a CYP3A4 and P-gp substrate; cobicistat is a P-gp and strong CYP3A4 inhibitor. Coadministration of a combined P-gp and strong CYP3A4 inhibitor increased the exposure of oral and intravenous lefamulin by 165% and 31%, respectively.
Lemborexant: (Major) Avoid coadministration of lemborexant and cobicistat as concurrent use is expected to significantly increase lemborexant exposure and the risk of adverse effects. Lemborexant is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of lemborexant with another strong CYP3A4 inhibitor increased the lemborexant AUC by up to 4.5-fold.
Leniolisib: (Major) Avoid concomitant use of leniolisib and cobicistat due to the risk for increased leniolisib exposure which may increase the risk for adverse effects. Leniolisib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use with another strong CYP3A inhibitor increased leniolisib overall exposure by 2-fold. (Moderate) Coadministration of tenofovir disoproxil fumarate with leniolisib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a BCRP substrate and leniolisib is a BCRP inhibitor.
Lesinurad: (Moderate) Elvitegravir may decrease the systemic exposure and therapeutic effect of lesinurad; monitor for potential reduction in efficacy. Elvitegravir is a mild CYP2C9 inducer, and lesinurad is a CYP2C9 substrate. In addition, lesinurad may decrease the systemic exposure and therapeutic efficacy of elvitegravir; monitor for potential reduction in efficacy. Elvitegravir is a CYP3A substrate, and lesinurad is a weak CYP3A inducer.
Lesinurad; Allopurinol: (Moderate) Elvitegravir may decrease the systemic exposure and therapeutic effect of lesinurad; monitor for potential reduction in efficacy. Elvitegravir is a mild CYP2C9 inducer, and lesinurad is a CYP2C9 substrate. In addition, lesinurad may decrease the systemic exposure and therapeutic efficacy of elvitegravir; monitor for potential reduction in efficacy. Elvitegravir is a CYP3A substrate, and lesinurad is a weak CYP3A inducer.
Letermovir: (Moderate) Administering cobicistat concurrently with letermovir may result in increased concentrations of both drugs. The impact on the concentration of cobicistat may be increased in patients who are receiving letermovir with cyclosporine. Closely monitor for adverse events, including tachycardia, atrial fibrillation, and gastrointestinal events. Cobicistat is an inhibitor of the organic anion-transporting polypeptides (OATP1B1/3), and a substrate of CYP3A4. Letermovir is an OATP1B1/3 substrate and a moderate CYP3A4 inhibitor. When given with cyclosporine, the combined effect of letermovir and cyclosporine on CYP3A4 substrates may be similar to a strong CYP3A4 inhibitor.
Leuprolide; Norethindrone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Levamlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Levoketoconazole: (Major) Avoid cobicistat for 2 weeks prior to and during treatment with ketoconazole. Concomitant use may increase exposure of both drugs and increase the risk of adverse effects. If concomitant use is necessary, monitor closely for adverse reactions; a ketoconazole dose reduction may be necessary. Both ketoconazole and cobicistat are CYP3A substrates and strong CYP3A inhibitors. (Major) Coadministration of ketoconazole with elvitegravir may result in increased plasma concentrations of both drugs. During concurrent use, a maximum ketoconazole dose of 200 mg/day is recommended. (Moderate) Monitor for an increase in tenofovir-related adverse effects if coadministration with ketoconazole is necessary. Concurrent use may increase tenofovir exposure. Tenofovir disoproxil fumarate is a P-gp substrate and ketoconazole is a P-gp inhibitor.
Levomilnacipran: (Major) Do not exceed a levomilnacipran dose of 80 mg once daily if coadministration with cobicistat is necessary. Levomilnacipran is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased levomilnacipran exposure by about 50%.
Levonorgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Levonorgestrel; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Lidocaine: (Moderate) Monitor for lidocaine-related adverse reactions if coadministration with cobicistat is necessary. Lidocaine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Lidocaine; Epinephrine: (Moderate) Monitor for lidocaine-related adverse reactions if coadministration with cobicistat is necessary. Lidocaine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Lidocaine; Prilocaine: (Moderate) Monitor for lidocaine-related adverse reactions if coadministration with cobicistat is necessary. Lidocaine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Linagliptin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Lomitapide: (Contraindicated) Concomitant use of cobicistat and lomitapide is contraindicated due to the potential of markedly increased lomitapide concentrations and the associated elevation of serum transaminases. Cobicistat is a strong CYP3A4 inhibitor. The exposure to lomitapide was increased 27-fold in the presence another strong CYP3A4 inhibitor.
Lonafarnib: (Contraindicated) Coadministration of lonafarnib and cobicistat is contraindicated; concurrent use may increase the exposure of both drugs and the risk of adverse effects. Lonafarnib is a sensitive CYP3A4 substrate and strong CYP3A4 inhibitor; cobicistat is a CYP3A4 substrate and strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the exposure of lonafarnib by 425%. (Moderate) Coadministration of tenofovir disoproxil fumarate with lonafarnib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-glycoprotein (P-gp) substrate and lonafarnib is a P-gp inhibitor.
Loperamide: (Moderate) Monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest), if coadministered with cobicistat. Concurrent use may increase loperamide exposure. Loperamide is a CYP3A4 and P-gp substrate and cobicistat is a strong CYP3A4 and P-gp inhibitor. Coadministration with another strong CYP3A4 and P-gp inhibitor increased loperamide exposure by 3.8-fold.
Loperamide; Simethicone: (Moderate) Monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest), if coadministered with cobicistat. Concurrent use may increase loperamide exposure. Loperamide is a CYP3A4 and P-gp substrate and cobicistat is a strong CYP3A4 and P-gp inhibitor. Coadministration with another strong CYP3A4 and P-gp inhibitor increased loperamide exposure by 3.8-fold.
Lopinavir; Ritonavir: (Contraindicated) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Moderate) Concurrent administration of elvitegravir with ritonavir may result in elevated elvitegravir plasma concentrations. Elvitegravir is a substrate of the hepatic isoenzyme CYP3A4. Ritonavir inhibits the CYP3A4 enzyme. Caution and close monitoring are advised if these drugs are administered together. (Minor) There are varying results in reports of an interaction between tenofovir and lopinavir; ritonavir. In one report, the concurrent administration of tenofovir with lopinavir; ritonavir increased tenofovir Cmax 31%, AUC 34%, and Cmin 29%, with slight (15%) decreases in lopinavir Cmax and AUC; the alterations may be a food effect rather than a drug-drug interaction. In another report, lopinavir; ritonavir (400 mg; 100 mg PO twice daily for 14 days) increased the tenofovir (300 mg/day PO) Cmin 51% and AUC 32%, with no effect seen on lopinavir; ritonavir pharmacokinetics. While the clinical significance of this interaction is unknown, and is suspected to be insignificant, patients receiving lopinavir; ritonavir with tenofovir should be monitored for tenofovir-associated adverse events.
Lorcaserin: (Moderate) Caution is warranted when cobicistat is administered with lorcaserin as there is a potential for elevated cobicistat concentrations. Lorcaserin is a CYP2D6 inhibitor. Cobicistat is a substrate of CYP2D6.
Lorlatinib: (Major) Avoid coadministration of lorlatinib with cobicistat due to increased plasma concentrations of lorlatinib, which may increase the incidence and severity of adverse reactions of lorlatinib; plasma concentrations of cobicistat may also decrease. If concomitant use is unavoidable, reduce the starting dose of lorlatinib from 100 mg to 75 mg once daily, or from 75 mg to 50 mg once daily. If cobicistat is discontinued, resume the original dose of lorlatinib after 3 half-lives of cobicistat. Lorlatinib is a CYP3A4 substrate and a moderate CYP3A4 inducer. Cobicistat is a CYP3A4 substrate and a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased lorlatinib exposure by 42%. Coadministration of cobicistat with moderate CYP3A4 inducers may reduce antiretroviral efficacy and increase the potential development of viral resistance. (Moderate) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is a CYP3A4 substrate and lorlatinib is a moderate CYP3A4 inducer.
Losartan: (Moderate) Caution is warranted when elvitegravir is administered with losartan as there is a potential for decreased losartan concentrations. Losartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Minor) Caution is warranted when cobicistat is administered with losartan as there is a potential for increased losartan concentrations. Losartan is a substrate of CYP3A4; cobicistat is an inhibitor of CYP3A4.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Caution is warranted when elvitegravir is administered with losartan as there is a potential for decreased losartan concentrations. Losartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Minor) Caution is warranted when cobicistat is administered with losartan as there is a potential for increased losartan concentrations. Losartan is a substrate of CYP3A4; cobicistat is an inhibitor of CYP3A4.
Lovastatin: (Contraindicated) Concomitant use of lovastatin with cobicistat is contraindicated due to the potential for myopathy, including rhabdomyolysis. Coadministration is expected to significantly increase lovastatin plasma concentrations. Lovastatin is a substrate for CYP3A4; cobicistat is a strong inhibitor of CYP3A. Coadministration with another strong CYP3A4 inhibitor increased lovastatin exposure by 11 to 36-fold.
Lumacaftor; Ivacaftor: (Major) Concomitant use of lumacaftor; ivacaftor and elvitegravir is not recommended, as significant decreases in elvitegravir plasma concentrations may occur. This may result in loss of virologic response and possible resistance. Elvitegravir is metabolized by CYP3A, and lumacaftor is a strong CYP3A inducer. (Major) Lumacaftor; ivacaftor may decrease the therapeutic efficacy of cobicistat; avoid concurrent use if possible. If concomitant use of cobicistat is necessary, monitor antiretroviral efficacy, consider the use of therapeutic drug monitoring, and adjust drug dosages as necessary. Lumacaftor; ivacaftor dosage adjustment is not required when cobicistat is started in a patient already taking lumacaftor; ivacaftor. However, if lumacaftor; ivacaftor is initiated in a patient already taking cobicistat, reduce the dose of lumacaftor; ivacaftor to 1 tablet PO daily or 1 packet of oral granules every other day for the first week of treatment, and then increase to the usual recommended daily dose. This dosage adjustment is also necessary if lumacaftor; ivacaftor therapy has been interrupted for more than 1 week and re-initiated while the patient is taking cobicistat. The 1-week lead-in period at the lower lumacaftor; ivacaftor dosage allows for lumacaftor's induction of CYP3A to reach steady state. Cobicistat is a substrate and strong inhibitor of CYP3A. Ivacaftor is a CYP3A substrate, and lumacaftor is a strong CYP3A inducer. Lumacaftor's induction of CYP3A may decrease the systemic exposure of cobicistat and decrease its therapeutic efficacy. Although cobicistat is a strong CYP3A4 inhibitor, net ivacaftor exposure at steady state is not expected to exceed that achieved with ivacaftor monotherapy (i.e., 150 mg PO every 12 hours) because of lumacaftor's CYP3A induction. In pharmacokinetic studies, coadministration of lumacaftor; ivacaftor with another strong CYP3A4 inhibitor increased ivacaftor exposure by 4.3-fold.
Lumacaftor; Ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Coadministration is not recommended in patients younger than 6 months. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as ivacaftor. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Lumateperone: (Major) Reduce the dose of lumateperone to 10.5 mg once daily if concomitant use of cobicistat is necessary. Concurrent use may increase lumateperone exposure and the risk of adverse effects. Lumateperone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with a strong CYP3A4 inhibitor increased lumateperone exposure by approximately 4-fold.
Lurasidone: (Contraindicated) Coadministration of cobicistat (or cobicistat containing medications) with lurasidone is contraindicated due to the potential for serious or life-threatening reactions, such as CNS effects and extrapyramidal symptoms. The plasma concentrations of lurasidone may be elevated when administered concurrently with cobicistat. Cobicistat is a strong CYP3A4 inhibitor, while lurasidone is a sensitive CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased lurasidone exposure by 9-fold.
Lurbinectedin: (Major) Avoid concomitant use of lurbinectedin and cobicistat due to the risk of increased lurbinectedin exposure which may increase the risk of adverse reactions. If concomitant use is necessary, reduce the dose of lurbinectedin by 50%. Lurbinectedin is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the overall exposure of lurbinectedin by 2.7-fold.
Macitentan: (Major) Avoid coadministration of macitentan with cobicistat due to increased plasma concentrations of macitentan. Macitentan is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased macitentan exposure by approximately 2.3-fold.
Magnesium Salicylate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Maprotiline: (Major) The plasma concentrations of maprotiline may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Maprotiline serum concentration monitoring may be useful to guide dosage adjustments and prevent toxicity. Cobicistat is a CYP2D6 inhibitor, while maprotiline is a CYP2D6 substrate.
Maraviroc: (Major) Coadministration of maraviroc (a substrate of CYP3A, P-gp, and OATP1B1) with cobicistat (a CYP3A4, P-gp, OATP1B1 inhibitor) may result in increased maraviroc concentrations. Reduce the dose of maraviroc when coadministered with cobicistat; coadministration is contraindicated in patients with CrCl less than 30 mL/min. Adjust the maraviroc dosage as follows when administered with cobicistat (with or without a concomitant CYP3A inducer): adults and children weighing 40 kg or more: 150 mg PO twice daily; children weighing 30 to 39 kg: 100 mg PO twice daily; children weighing 20 to 29 kg: 75 mg PO twice daily (or 80 mg PO twice daily for solution); children weighing 10 to 19 kg: 50 mg PO twice daily; children weighing 2 to 9 kg: use not recommended. (Major) Coadministration of maraviroc, a CYP3A substrate, with elvitegravir boosted with ritonavir, a strong CYP3A4 inhibitor, may result in increased maraviroc concentrations. Reduce the dose of maraviroc when coadministered with strong CYP3A inhibitors; coadministration of maraviroc with strong CYP3A inhibitors is contraindicated in patients with CrCl less than 30 mL/min. Adjust the maraviroc dosage as follows when administered with elvitegravir boosted with ritonavir (with or without a concomitant CYP3A inducer): adults and children weighing 40 kg or more: 150 mg PO twice daily; children weighing 30 to 39 kg: 100 mg PO twice daily; children weighing 20 to 29 kg: 75 mg PO twice daily (or 80 mg PO twice daily for solution); children weighing 10 to 19 kg: 50 mg PO twice daily; children weighing 2 to 9 kg: use not recommended.
Maribavir: (Moderate) Coadministration of tenofovir disoproxil fumarate with maribavir may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and maribavir is a P-gp and BCRP inhibitor.
Mavacamten: (Contraindicated) Mavacamten is contraindicated for use with cobicistat due to risk of heart failure due to systolic dysfunction. Concomitant use increases mavacamten exposure and may decrease the plasma concentrations of cobicistat leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Mavacamten is a substrate and moderate inducer of CYP3A and cobicistat is a substrate and strong inhibitor of CYP3A. Concomitant use with a strong CYP3A inhibitor is predicted to increase mavacamten overall exposure up to 130%. (Moderate) Coadministration of elvitegravir with mavacamten may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is a CYP3A substrate and mavacamten is a moderate CYP3A inducer.
Meclizine: (Moderate) The plasma concentrations of meclizine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while meclizine is a CYP2D6 substrate.
Meclofenamate Sodium: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Medroxyprogesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with medroxyprogesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
Mefenamic Acid: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Mefloquine: (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as mefloquine. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Moderate) The plasma concentrations of mefloquine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or neurophsychiatric effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and P-glycoprotein (P-gp) inhibitor, while mefloquine is a CYP3A4 and P-gp substrate.
Meloxicam: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Caution is warranted when elvitegravir is administered with meloxicam as there is a potential for decreased meloxicam concentrations. Meloxicam is primarily metabolized by CYP2C9, while elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Metformin; Repaglinide: (Moderate) Coadministration of repaglinide and cobicistat may increase plasma concentrations of repaglinide; if coadministration is necessary, repaglinide dosage adjustment may be required and an increased frequency of glucose monitoring is recommended. Cobicistat is a strong CYP3A4 inhibitor and an inhibitor of organic anion transporting polypeptide (OATP). Repaglinide is a CYP3A4 and OATP1B1 substrate. Coadministration with other strong CYP3A4 inhibitors increased repaglinide exposure by up to 1.5-fold. (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Metformin; Rosiglitazone: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed. (Minor) Plasma concentrations of rosiglitazone may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased hypoglycemic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while rosiglitazone is a CYP2C9 substrate.
Metformin; Saxagliptin: (Major) Limit the dose of saxagliptin to 2.5 mg PO once daily when administered with cobicistat due to significantly increased saxagliptin exposure. Saxagliptin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 100 mg dose of saxagliptin and a single 20 mg dose of saxagliptin increased the saxagliptin AUC by 2.45-fold and 3.67-fold, respectively. (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Metformin; Sitagliptin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Methadone: (Moderate) Caution is warranted when elvitegravir is administered with methadone as there is a potential for decreased methadone concentrations and the dosage of methadone may need to be increased. Methadone is partially metabolized by CYP2C9, while elvitegravir is a CYP2C9 inducer. (Moderate) The plasma concentrations of methadone may be elevated when administered concurrently with cobicistat. When initiating methadone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest methadone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on methadone, an adjustment of methadone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Methadone is metabolized primarily by the cytochrome P450 isoenzymes CYP2C19, CYP3A4, and CYP2B6, and to a lesser extent, by CYP2C9 and CYP2D6. Methadone also is a substrate of P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp.
Methamphetamine: (Moderate) The plasma concentrations of methamphetamine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while methamphetamine is a CYP2D6 substrate.
Methenamine; Sodium Salicylate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Methotrexate: (Major) Avoid concomitant use of methotrexate with tenofovir disoproxil fumarate due to the risk of additive nephrotoxicity as well as an increased risk of severe methotrexate-related adverse reactions. If concomitant use is unavoidable, closely monitor for adverse reactions. Tenofovir disoproxil fumarate and methotrexate are both nephrotoxic drugs; methotrexate is also renally eliminated. Coadministration of methotrexate with tenofovir disoproxil fumarate may result in decreased renal function as well as increased methotrexate plasma concentrations.
Methylergonovine: (Contraindicated) Coadministration of methylergonovine with cobicistat is contraindicated. Cobicistat is an inhibitor of CYP3A, and plasma concentrations of drugs extensively metabolized by this enzyme, such as ergot alkaloids, are expected to increase with concurrent use. Elevated plasma concentrations of ergot alkaloids are associated with risk of acute ergot toxicity which is characterized by peripheral vasospasm and ischemia of the extremities and other tissues.
Methylprednisolone: (Moderate) Coadministration of methylprednisolone with cobicistat may cause elevated methylprednisolone serum concentrations, potentially resulting in Cushing's syndrome or adrenal suppression. Cobicistat is a CYP3A4 inhibitor, while methylprednisolone is a CYP3A4 substrate. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Metoclopramide: (Moderate) Caution is warranted when cobicistat is administered with metoclopramide as there is a potential for elevated metoclopramide and cobicistat concentrations. Metoclopramide is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6.
Metoprolol: (Moderate) Monitor for increased metoprolol adverse reactions including bradycardia and hypotension during coadministration. A dosage reduction for metoprolol may be needed based on response. Concurrent use may increase metoprolol exposure. Metoprolol is a CYP2D6 substrate; cobicistat is a weak CYP2D6 inhibitor.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for increased metoprolol adverse reactions including bradycardia and hypotension during coadministration. A dosage reduction for metoprolol may be needed based on response. Concurrent use may increase metoprolol exposure. Metoprolol is a CYP2D6 substrate; cobicistat is a weak CYP2D6 inhibitor.
Mexiletine: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of mexiletine with cobicistat. Mexiletine is a substrate for CYP2D6; cobicistat is an inhibitor of this enzyme. Concurrent use may result in elevated mexiletine plasma concentration.
Midazolam: (Major) Use of orally administered midazolam with cobicistat is contraindicated due to the risk for prolonged/increased sedation and respiratory depression. Midazolam is extensively metabolized by CYP3A4; cobicistat is a strong inhibitor of this enzyme. Concurrent use is expected to produce large increases in the plasma concentrations of midazolam. Elevations in midazolam concentrations may also be observed with the parenteral formulation of midazolam; however, this formulation may be administered with cobicistat if given in as setting with close clinical monitoring and appropriate medical management. Consider reducing the dose of parenteral midazolam.
Midostaurin: (Major) Avoid the concomitant use of midostaurin and cobicistat due to the risk of increased midostaurin exposure which may increase the incidence and severity of adverse reactions. If concomitant use cannot be avoided, monitor patients for signs and symptoms of midostaurin toxicity, particularly during the first week of midostaurin therapy for those with systemic mastocytosis/mast cell leukemia and during the first week of each cycle for those with acute myeloid leukemia. Midostaurin is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration of one strong CYP3A4 inhibitor with a single dose of midostaurin increased the exposure of midostaurin and its active metabolites CGP62221 and CGP52421 by 10.4-fold, 3.5-fold, and 1.2-fold, respectively. Coadministration of another strong CYP3A4 inhibitor with twice daily doses of midostaurin increased Day 28 trough concentrations of midostaurin, CGP62221, and CGP52421 by 2.1-fold, 1.2-fold, and 1.3-fold respectively compared with day 21 trough levels with midostaurin alone. (Moderate) Coadministration of tenofovir disoproxil fumarate with midostaurin may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a BCRP substrate and midostaurin is a BCRP inhibitor.
Mifepristone: (Major) Caution is advised when administering cobicistat with mifepristone because increased serum concentrations of either drug may occur. When mifepristone is used in the treatment of Cushing's syndrome, coadministration with cobicistat should be done only when necessary, and in such cases the dose of mifepristone should be limited to a maximum dose of 900 mg per day. In a patient already receiving cobicistat, initiate mifepristone at a dose of 300 mg and titrate to a maximum of 900 mg if clinically indicated. If therapy with cobicistat is initiated in a patient already receiving mifepristone 300 mg, dosage adjustments are not required. If therapy with cobicistat is initiated in a patient already receiving mifepristone 600 mg, reduce dose of mifepristone to 300 mg and titrate to a maximum of 600 mg if clinically indicated. If therapy with cobicistat is initiated in a patient already receiving 900 mg, reduce dose of mifepristone to 600 mg and titrate to a maximum of 900 mg if clinically indicated. If therapy with cobicistat is initiated in a patient already receiving 1,200 mg, reduce the mifepristone dose to 900 mg. Both mifepristone and cobicistat are substrates and strong inhibitors of CYP3A4.
Mirabegron: (Moderate) Caution is warranted when cobicistat is administered with mirabegron as there is a potential for elevated cobicistat concentrations. Mirabegron is a moderate CYP2D6 inhibitor. Cobicistat is a substrate of CYP2D6 and CYP3A4.
Mirtazapine: (Moderate) Monitor for an increase in mirtazapine-related adverse reactions if coadministration with cobicistat is necessary. Mirtazapine is a CYP3A substrate; cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the Cmax and AUC of a single dose of mirtazapine by approximately 40% and 50%, respectively.
Mirvetuximab Soravtansine: (Moderate) Closely monitor for mirvetuximab soravtansine-related adverse reactions if concomitant use of cobicistat is necessary. DM4, the cytotoxic component of mirvetuximab soravtansine, is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use may increase unconjugated DM4 exposure.
Mitapivat: (Major) Avoid coadministration of mitapivat with cobicistat due to increased risk of adverse reactions from mitapivat. Coadministration increases mitapivat concentrations. Mitapivat is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use with other strong CYP3A inhibitors increased mitapivat overall exposure by 3.6 to 4.9-fold. (Moderate) Coadministration of tenofovir disoproxil fumarate with mitapivat may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and mitapivat is a P-gp inhibitor.
Mitotane: (Contraindicated) Coadministration of mitotane with cobicistat is contraindicated. Mitotane is a strong inducer of CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Use caution if mitotane and elvitegravir are used concomitantly, due to potential decreased concentrations of elvitegravir leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Mitotane is a strong CYP3A4 inducer and elvitegravir is a CYP3A4 substrate; coadministration may result in decreased plasma concentrations of elvitegravir.
Mobocertinib: (Major) Avoid concomitant use of mobocertinib and cobicistat. Concomitant use may increase mobocertinib exposure and the risk for adverse reactions such as QT prolongation. Mobocertinib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Use of a strong CYP3A inhibitor is predicted to increase the overall exposure of mobocertinib and its active metabolites by 374% to 419%.
Modafinil: (Major) Coadministration of cobicistat with modafinil is not recommended as there is a potential for elevated modafinil concentrations and decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Modafinil is a CYP3A4 substrate/inducer. Cobicistat is an inhibitor/substrate of CYP3A4. (Major) Coadministration of elvitegravir with modafinil is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Modafinil is a CYP3A4 inducer, while elvitegravir is a substrate of CYP3A4.
Mometasone: (Moderate) Coadministration of mometasone with cobicistat may cause elevated mometasone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Mometasone is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Morphine: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
Morphine; Naltrexone: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
Nabumetone: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Nafcillin: (Major) Caution is warranted when cobicistat is administered with nafcillin as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Nafcillin is an inducer of CYP3A4. Cobicistat is a CYP3A4 substrate.
Naldemedine: (Moderate) Monitor for potential naldemedine-related adverse reactions if coadministered with cobicistat. The plasma concentrations of naldemedine may be increased during concurrent use. Naldemedine is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a moderate P-gp inhibitor and strong CYP3A4 inhibitor.
Naloxegol: (Contraindicated) Concomitant use of naloxegol with cobicistat is contraindicated. Naloxegol is metabolized primarily by CYP3A. Strong CYP3A4 inhibitors, such as cobicistat, can significantly increase exposure to naloxegol which may precipitate opioid withdrawal symptoms such as hyperhidrosis, chills, diarrhea, abdominal pain, anxiety, irritability, and yawning.
Naloxone: (Moderate) The plasma concentrations of buprenorphine and naloxone may be elevated when administered concurrently with cobicistat. When initiating buprenorphine; naloxone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest buprenorphine; naloxone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on buprenorphine; naloxone, an adjustment of buprenorphine; naloxone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while buprenorphine is a CYP3A4 substrate.
Nanoparticle Albumin-Bound Paclitaxel: (Moderate) Monitor for an increase in paclitaxel-related adverse reactions if coadministration of nab-paclitaxel with cobicistat is necessary due to the risk of increased plasma concentrations of paclitaxel. Nab-paclitaxel is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. In vitro, coadministration with both strong and moderate CYP3A4 inhibitors increased paclitaxel exposure; however, the concentrations used exceeded those found in vivo following normal therapeutic doses. The pharmacokinetics of paclitaxel may also be altered in vivo as a result of interactions with CYP3A4 inhibitors.
Nanoparticle Albumin-Bound Sirolimus: (Major) Avoid concomitant use of sirolimus and cobicistat. Coadministration may increase sirolimus concentrations and increase the risk for sirolimus-related adverse effects. Sirolimus is a CYP3A and P-gp substrate and cobicistat is a strong CYP3A and P-gp inhibitor.
Naproxen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of naproxen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while naproxen is a CYP2C9 substrate.
Naproxen; Esomeprazole: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of naproxen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while naproxen is a CYP2C9 substrate. (Minor) Use caution when administering cobicistat and esomeprazole concurrently. Cobicistat is an inhibitor of CYP3A, and esomeprazole is partially metabolized by CYP3A. Coadministration of cobicistat with CYP3A substrates, such as esomeprazole, can theoretically increase esomeprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
Naproxen; Pseudoephedrine: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of naproxen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while naproxen is a CYP2C9 substrate.
Nateglinide: (Minor) Caution is warranted when elvitegravir is administered with nateglinide as there is a potential for decreased nateglinide concentrations. Nateglinide is a primary substrate for CYP2C9 (70%); elvitegravir is a CYP2C9 inducer.
Nebivolol: (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with cobicistat. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as cobicistat, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible.
Nebivolol; Valsartan: (Moderate) Caution is warranted when elvitegravir is administered with valsartan as there is a potential for decreased valsartan concentrations. Valsartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with cobicistat. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as cobicistat, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
Nefazodone: (Moderate) Caution is warranted when cobicistat is administered with nefazodone as there is a potential for elevated nefazodone and cobicistat concentrations. Both nefazodone and cobicistat are substrates and strong inhibitors of CYP3A4.
Nelfinavir: (Major) Avoid coadministration of nelfinavir with elvitegravir. No data are available regarding use of these drugs concurrently. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as nelfinavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Neratinib: (Major) Avoid concomitant use of cobicistat with neratinib due to an increased risk of neratinib-related toxicity. Neratinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased neratinib exposure by 381%; concomitant use with other strong inhibitors of CYP3A4 may also increase neratinib concentrations. (Moderate) Coadministration of tenofovir disoproxil fumarate with neratinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-glycoprotein (P-gp) substrate and neratinib is a P-gp inhibitor.
Netupitant, Fosnetupitant; Palonosetron: (Moderate) Netupitant is a moderate inhibitor of CYP3A4 and should be used with caution in patients receiving concomitant medications that are primarily metabolized through CYP3A4, such as cobicistat. The plasma concentrations of cobicistat can increase when co-administered with netupitant; the inhibitory effect on CYP3A4 can last for multiple days. In addition, netupitant is mainly metabolized by CYP3A4. Cobicistat has been shown to be a strong CYP3A4 inhibitor, and may increase netupitant exposure. Coadministration with another strong CYP3A4 inhibitor increased netupitant exposure by 140%. No dosage adjustment is necessary. (Moderate) The plasma concentrations of palonosetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is an inhibitor of CYP3A4 and CYP2D6; palonosetron is a substrate of both CYP3A4 and CYP2D6.
Nevirapine: (Contraindicated) Coadministration of nevirapine with regimens containing cobicistat and atazanavir are contraindicated; use of nevirapine with regimens containing cobicistat and darunavir are also not recommended. Nevirapine is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, while atazanavir are darunavir are CYP3A4 substrates. If these drugs are used together, the concentrations of nevirapine may increase and the concentrations of atazanavir, darunavir, and cobicistat may decrease; thereby, increasing the risk for nevirapine-associated adverse reactions and potentally decreasing the antiretroviral efficacy of atazanavir and darunavir. (Major) Avoid concurrent use of nevirapine and elvitegravir. Concomitant use may decrease plasma concentrations of elvitegravir resulting in loss of antiviral efficacy and potentially the development of viral resistance. Elvitegravir is a CYP3A substrate and nevirapine is a weak CYP3A inducer.
Niacin; Simvastatin: (Contraindicated) Concomitant use of simvastatin with cobicistat is contraindicated due to increased simvastatin exposure and potential for myopathy, including rhabdomyolysis. Simvastatin is a substrate for CYP3A4; cobicistat is a strong CYP3A4 inhibitor.
Nicardipine: (Moderate) Coadministration of cobicistat with nicardipine may result in elevated cobicistat serum concentrations. Cobicistat is a substrate of CYP3A4 and CYP2D6. Nicardipine is an inhibitor of CYP2D6 and CYP3A4.
Nicotine: (Minor) Caution is warranted when cobicistat is administered with nicotine as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Nicotine is an inducer of CYP2D6; cobicistat is a CYP2D6 substrate.
Nifedipine: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as nifedipine, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate reductions are advised.
Nilotinib: (Major) Avoid the concomitant use of nilotinib and cobicistat. If coadministration is required, monitor patients closely for prolongation of the QT interval and reduce the nilotinib dose to 300 mg once daily in patients with resistant or intolerant Ph+ CML or to 200 mg once daily in patients with newly diagnosed Ph+ CML. If cobicistat is discontinued, a washout period should be allowed before adjusting the nilotinib dosage upward to the indicated dose. Nilotinib is a substrate and moderate inhibitor of CYP3A4 and cobicistat is a substrate and a strong inhibitor of CYP3A4.
Nimodipine: (Major) Avoid coadministration of nimodipine with cobicistat due to the risk of significant hypotension. If concomitant use is unavoidable, monitor blood pressure and reduce the dose of nimodipine as clinically appropriate. Nimodipine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Nintedanib: (Moderate) Dual inhibitors of P-glycoprotein (P-gp) and CYP3A4, such as cobicistat, may increase the exposure and clinical effect of nintedanib. If use together is necessary, closely monitor for increased nintedanib side effects including gastrointestinal toxicity (nausea, vomiting, diarrhea, abdominal pain, loss of appetite), headache, elevated liver enzymes, and hypertension. A dose reduction, interruption of therapy, or discontinuation of nintedanib therapy may be necessary. Cobicistat is a mild inhibitor of both P-gp and CYP3A4; nintedanib is a P-gp substrate and a minor CYP3A4 substrate. In drug interactions studies, administration of nintedanib with a dual P-gp and CYP3A4 inhibitor increased nintedanib AUC by 60%.
Nirmatrelvir; Ritonavir: (Contraindicated) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Moderate) Concurrent administration of elvitegravir with ritonavir may result in elevated elvitegravir plasma concentrations. Elvitegravir is a substrate of the hepatic isoenzyme CYP3A4. Ritonavir inhibits the CYP3A4 enzyme. Caution and close monitoring are advised if these drugs are administered together.
Nisoldipine: (Major) Avoid coadministration of nisoldipine with cobicistat due to increased plasma concentrations of nisoldipine. If coadministration is unavoidable, monitor blood pressure closely during concurrent use of these medications. Nisoldipine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Non-Ionic Contrast Media: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as radiopaque contrast agents. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Nonsteroidal antiinflammatory drugs: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Norethindrone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Norethindrone; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Norgestimate; Ethinyl Estradiol: (Major) Concurrent administration of cobicistat and norgestimate results in increased norgestimate serum concentrations. Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is also the potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Norgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Nortriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Olanzapine: (Moderate) Caution is warranted when cobicistat is administered with olanzapine as there is a potential for elevated olanzapine concentrations. Olanzapine is a substrate of CYP2D6. Cobicistat is an inhibitor of CYP2D6.
Olanzapine; Fluoxetine: (Moderate) Caution is warranted when cobicistat is administered with olanzapine as there is a potential for elevated olanzapine concentrations. Olanzapine is a substrate of CYP2D6. Cobicistat is an inhibitor of CYP2D6. (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Olanzapine; Samidorphan: (Moderate) Caution is warranted when cobicistat is administered with olanzapine as there is a potential for elevated olanzapine concentrations. Olanzapine is a substrate of CYP2D6. Cobicistat is an inhibitor of CYP2D6.
Olaparib: (Major) Avoid coadministration of olaparib with cobicistat due to the risk of increased olaparib-related adverse reactions. If concomitant use is unavoidable, reduce the dose of olaparib to 100 mg twice daily; the original dose may be resumed 3 to 5 elimination half-lives after cobicistat is discontinued. Olaparib is a CYP3A substrate and cobicistat is a strong CYP3A4 inhibitor; concomitant use may increase olaparib exposure. Coadministration with another strong CYP3A inhibitor increased the olaparib Cmax by 42% and the AUC by 170%.
Oliceridine: (Moderate) Monitor patients closely for respiratory depression and sedation at frequent intervals and base subsequent doses on the patient's severity of pain and response to treatment if concomitant administration of oliceridine and cobicistat is necessary; less frequent dosing of oliceridine may be required. Concomitant use of oliceridine and cobicistat may increase the plasma concentration of oliceridine, resulting in increased or prolonged opioid effects. If cobicistat is discontinued, consider increasing the oliceridine dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oliceridine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Olopatadine; Mometasone: (Moderate) Coadministration of mometasone with cobicistat may cause elevated mometasone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Mometasone is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Omaveloxolone: (Major) Avoid concomitant use of omaveloxolone and cobicistat. If concomitant use is necessary, decrease omaveloxolone dose to 50 mg once daily. Concomitant use may increase omaveloxolone exposure and the risk for omaveloxolone-related adverse effects. Omaveloxolone is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use with another strong CYP3A inhibitor increased omaveloxolone overall exposure by 4-fold.
Omeprazole: (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
Omeprazole; Amoxicillin; Rifabutin: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. (Major) Coadministration of rifabutin with elvitegravir may result in reduced elvitegravir concentrations and elevated rifabutin concentrations. If these drugs must be used concurrently, reduce the dose of rifabutin by at least 75% of the usual 300 mg/day dose (e.g., 150 mg every other day or 3x/week). If the rifabutin dose is reduced, no dose adjustment is required for elvitegravir. Monitor closely for rifabutin-associated adverse events. (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
Omeprazole; Sodium Bicarbonate: (Moderate) Separate administration of elvitegravir and antacids by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations. (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
Ondansetron: (Moderate) The plasma concentrations of ondansetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or CNS effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-glycoprotein (P-gp) inhibitor. Ondansetron is a CYP3A4, CYP2D6, and P-gp substrate.
Oral Contraceptives: (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Oritavancin: (Major) Coadministration of elvitegravir with oritavancin is not recommended. Elvitegravir is metabolized by CYP3A4; oritavancin is a weak CYP3A4 inducer. Plasma concentrations and efficacy of elvitegravir may be reduced if these drugs are administered concurrently. (Major) Plasma concentrations and efficacy of cobicistat and/or the drugs that are boosted by cobicistat may be reduced if these drugs are administered concurrently with oritavancin. Cobicistat is metabolized by CYP3A4 and CYP2D6; oritavancin is a weak CYP3A4 and CYP2D6 inducer. Cobicistat is a CYP3A4 inhibitor indicated to increase systemic exposure of other antiretrovirals.
Orlistat: (Major) According to the manufacturer of orlistat, HIV RNA levels should be frequently monitored in patients receiving orlistat while being treated for HIV infection with tenofovir, PMPA. Loss of virological control has been reported in HIV-infected patients taking orlistat with tenofovir disoproxil fumarate and emtricitabine; efavirenz; tenofovir disoproxil fumarate. The exact mechanism for this interaction is not known, but may involve inhibition of systemic absorption of the anti-retroviral agent. If an increased HIV viral load is confirmed, orlistat should be discontinued. (Moderate) According to the manufacturer of orlistat, HIV RNA levels should be frequently monitored in patients receiving orlistat while being treated for HIV infection with anti-retroviral nucleoside reverse transcriptase inhibitors (NRTIs). Loss of virological control has been reported in HIV-infected patients taking orlistat with atazanavir, ritonavir, tenofovir disoproxil fumarate, emtricitabine, lopinavir; ritonavir, and emtricitabine; efavirenz; tenofovir disoproxil fumarate. The exact mechanism for this interaction is not known, but may involve inhibition of systemic absorption of the anti-retroviral agent. If an increased HIV viral load is confirmed, orlistat should be discontinued.
Osilodrostat: (Major) Reduce the dose of osilodrostat by one-half during coadministration of cobicistat; concurrent use may increase osilodrostat exposure and the risk of osilodrostat-related adverse reactions. Osilodrostat is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Osimertinib: (Moderate) Monitor for an increase in tenofovir-related adverse reactions if coadministration with osimertinib is necessary. Concomitant use may result in increased tenofovir absorption. Tenofovir disoproxil is a BCRP and P-glycoprotein (P-gp) substrate. Osimertinib is a BCRP and P-gp inhibitor.
Ospemifene: (Moderate) Monitor for an increase in ospemifene-related adverse reactions if coadministration with cobicistat is necessary. Ospemifene is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Oteseconazole: (Moderate) Coadministration of tenofovir disoproxil fumarate with oteseconazole may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a BCRP substrate and oteseconazole is a BCRP inhibitor.
Oxaliplatin: (Major) Avoid coadministration of oxaliplatin with tenofovir disoproxil fumarate due to the risk of increased oxaliplatin-related adverse reactions. Tenofovir disoproxil fumarate is known to be potentially nephrotoxic; because platinum-containing drugs like oxaliplatin are eliminated primarily through the kidney, oxaliplatin clearance may be decreased by coadministration with nephrotoxic agents.
Oxaprozin: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Oxcarbazepine: (Major) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Oxcarbazepine induces the CYP3A4 metabolism of elvitegravir. Consider an alternative anticonvulsant when using elvitegravir. The combination product cobicistat; elvitegravir; emtricitabine; tenofovir is contraindicated in combination with oxcarbazepine as the concentrations of both elvitegravir and cobicistat may be significantly decreased. (Major) Coadministration of oxcarbazepine with regimens containing cobicistat and atazanavir or darunavir should be avoided. If these drugs are used together, significant decreases in the plasma concentrations of cobicistat, atazanavir and potentally darunavir may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
Oxybutynin: (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone.
Paclitaxel: (Moderate) Plasma concentrations of paclitaxel may be elevated when administered concurrently with cobicistat. Cobicistat is a strong inhibitor of CYP3A4 and P-glycoprotein (P-gp) inhibitor, while paclitaxel is a CYP3A4 and P-gp substrate. Some experts state that pharmacokinetic interactions between paclitaxel and some CYP3A4 inhibitors do not appear to be clinically significant. However, combining the drugs in clinical practice may require close monitoring to ensure proper therapeutic responses.
Pacritinib: (Contraindicated) Concurrent use of pacritinib with cobicistat is contraindicated due to increased pacritinib exposure which increases the risk of adverse reactions. Pacritinib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. (Moderate) Concomitant use of tenofovir disoproxil fumarate with pacritinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate; pacritinib is a P-gp and BCRP inhibitor.
Palbociclib: (Major) Avoid coadministration of cobicistat with palbociclib; significantly increased plasma exposure of palbociclib may occur. If concomitant use cannot be avoided, reduce the dose of palbociclib to 75 mg PO once daily and monitor for increased adverse reactions. If cobicistat is discontinued, increase the palbociclib dose (after 3 to 5 half-lives of cobicistat) to the dose used before initiation of cobicistat. Palbociclib is primarily metabolized by CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. In a drug interaction trial, coadministration with another strong CYP3A4 inhibitor increased the AUC and Cmax of palbociclib by 87% and 34%, respectively.
Palonosetron: (Moderate) The plasma concentrations of palonosetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is an inhibitor of CYP3A4 and CYP2D6; palonosetron is a substrate of both CYP3A4 and CYP2D6.
Palovarotene: (Major) Avoid concomitant use of palovarotene and cobicistat due to the risk for increased palovarotene exposure which may increase the risk for adverse effects. Palovarotene is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use with another strong CYP3A inhibitor increased palovarotene overall exposure by 3-fold.
Pamidronate: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as pamidronate. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Panobinostat: (Major) Reduce the starting dose of panobinostat to 10 mg when coadministered with cobicistat. Concurrent use may increase systemic exposure of panobinostat. Panobinostat is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the AUC of panobinostat by 73%.
Paricalcitol: (Moderate) Monitor plasma PTH and serum calcium and phosphorous concentrations if a patient initiates or discontinues therapy with both paricalcitol and cobicistat, or during periods of dose titration. If hypercalcemia occurs, the dose of paricalcitol should be reduced or withheld until these parameters are normalized. Paricalcitol is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor approximately doubled the exposure of paricalcitol.
Paromomycin: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as aminoglycosides. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and aminoglycosides are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Paroxetine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Pazopanib: (Major) Avoid coadministration of pazopanib and cobicistat due to the potential for increased exposure of both pazopanib and cobicistat. If concurrent use is unavoidable, reduce the pazopanib dose to 400 mg PO once daily; further dose adjustments may be necessary if adverse effects occur. Pazopanib is an inhibitor and substrate of CYP3A4; cobicistat is a strong CYP3A4 inhibitor and a CYP3A4 substrate. Concurrent use of pazopanib another strong CYP3A4 inhibitor increased the Cmax and AUC of pazopanib by 1.5-fold and 1.7-fold, respectively. In addition, pazopanib is a substrate/inhibitor of P-glycoprotein (P-gp), an inhibitor of CYP2D6, and a substrate of breast cancer resistance protein (BCRP). Cobicistat is an inhibitor of P-gp, BCRP, and a substrate/inhibitor of CYP2D6. (Major) Caution is warranted when elvitegravir is administered with pazopanib as there is a potential for elevated concentrations of both drugs. Both drugs are substrates and inhibitors of CYP3A4.
Pemigatinib: (Major) Avoid coadministration of pemigatinib and cobicistat due to the risk of increased pemigatinib exposure which may increase the risk of adverse reactions. If coadministration is unavoidable, reduce the dose of pemigatinib to 9 mg PO once daily if original dose was 13.5 mg per day and to 4.5 mg PO once daily if original dose was 9 mg per day. If cobicistat is discontinued, resume the original pemigatinib dose after 3 elimination half-lives of cobicistat. Pemigatinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased pemigatinib exposure by 88%.
Pentamidine: (Moderate) The plasma concentrations of pentamidine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as nephrotoxicity or electrolyte disorders, is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while pentamidine is a CYP2D6 substrate.
Pentazocine; Naloxone: (Moderate) The plasma concentrations of buprenorphine and naloxone may be elevated when administered concurrently with cobicistat. When initiating buprenorphine; naloxone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest buprenorphine; naloxone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on buprenorphine; naloxone, an adjustment of buprenorphine; naloxone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while buprenorphine is a CYP3A4 substrate.
Perampanel: (Major) Caution is warranted when cobicistat is administered with perampanel as there is a potential for elevated perampanel concentrations and decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Perampanel is a substrate and inducer of CYP3A4. Cobicistat is a CYP3A4 substrate and inhibitor. (Major) Caution is warranted when elvitegravir is administered with perampanel as there is a potential for decreased concentrations of elvitegravir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Perampanel is an inducer of CYP3A4. Elvitegravir is a CYP3A4 substrate.
Perindopril; Amlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Perphenazine: (Moderate) The plasma concentrations of perphenazine may be elevated when administered concurrently with cobicistat. During coadministration, a reduction in the perphenazine dose may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is an inhibitor of CYP2D6, an isoenzyme responsible for the metabolism of perphenazine. These drugs used in combination may result in elevated perphenazine plasma concentrations, causing an increased risk for perphenazine-related adverse events.
Perphenazine; Amitriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations. (Moderate) The plasma concentrations of perphenazine may be elevated when administered concurrently with cobicistat. During coadministration, a reduction in the perphenazine dose may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is an inhibitor of CYP2D6, an isoenzyme responsible for the metabolism of perphenazine. These drugs used in combination may result in elevated perphenazine plasma concentrations, causing an increased risk for perphenazine-related adverse events.
Pexidartinib: (Major) Avoid concomitant use of pexidartinib and cobicistat due to the risk of increased pexidartinib exposure which may increase the risk for adverse effects; concomitant use may also decrease cobicistat plasma concentrations and reduce its efficacy. If concomitant use is necessary, reduce the pexidartinib dosage as follows: 500 mg/day or 375 mg/day of pexidartinib, reduce to 125 mg twice daily; 250 mg/day of pexidartinib, reduce to 125 mg once daily. If cobicistat is discontinued, increase the pexidartinib dose to the original dose after 3 plasma half-lives of cobicistat. Pexidartinib is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. Coadministration of another strong CYP3A inhibitor increased pexidartinib exposure by 70%. (Moderate) Coadministration of elvitegravir with pexidartinib may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is a CYP3A4 substrate and pexidartinib is a moderate CYP3A4 inducer.
Phenobarbital: (Contraindicated) Coadministration of phenobarbital with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy. (Major) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Phenobarbital induces the CYP3A4 metabolism of elvitegravir. Consider an alternative anticonvulsant when using elvitegravir. The combination product cobicistat; elvitegravir; emtricitabine; tenofovir is contraindicated in combination with phenobarbital as the concentrations of both elvitegravir and cobicistat may be significantly decreased.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Contraindicated) Coadministration of phenobarbital with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy. (Major) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Phenobarbital induces the CYP3A4 metabolism of elvitegravir. Consider an alternative anticonvulsant when using elvitegravir. The combination product cobicistat; elvitegravir; emtricitabine; tenofovir is contraindicated in combination with phenobarbital as the concentrations of both elvitegravir and cobicistat may be significantly decreased.
Phentermine; Topiramate: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with topiramate as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Elvitegravir is a CYP3A4 substrate.
Phenytoin: (Contraindicated) Coadministration of phenytoin with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy. (Major) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Phenytoin induces the CYP3A4 metabolism of elvitegravir. Consider an alternative anticonvulsant when using elvitegravir. The combination product cobicistat; elvitegravir; emtricitabine; tenofovir is contraindicated in combination with phenytoin as the concentrations of both elvitegravir and cobicistat may be significantly decreased.
Pimavanserin: (Major) Reduce the dose of pimavanserin to 10 mg PO once daily and monitor for pimavanserin-related adverse reactions, including nausea, vomiting, confusion, loss of balance or coordination, and QT prolongation if coadministration with cobcistat is necessary. Concurrent use may increase pimavanserin exposure. Pimavanserin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with a strong CYP3A4 inhibitor increased exposure to pimavanserin by 3-fold.
Pimozide: (Contraindicated) Coadministration of pimozide with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor; plasma concentrations of drugs extensively metabolized by these enzymes, such as pimozide, are expected to increase with concurrent use. Elevated plasma concentrations of pimozide have been associated with QT prolongation and serious cardiovascular adverse events including death due to torsade de pointes.
Pioglitazone; Glimepiride: (Minor) Plasma concentrations of glimepiride may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased hypoglycemic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while glimepiride is a CYP2C9 substrate.
Pioglitazone; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
Pirfenidone: (Moderate) Caution is warranted when cobicistat is administered with pirfenidone as there is a potential for elevated concentrations of both drugs. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a substrate/inhibitor of CYP3A4 and CYP2D6. Pirfenidone is a substrate/inhibitor of CYP2D6 and a CYP3A4 inhibitor.
Piroxicam: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Pirtobrutinib: (Major) Avoid concomitant use of pirtobrutinib and cobicistat due to the risk of increased pirtobrutinib exposure which may increase the risk for adverse effects. If concomitant use is necessary, reduce the pirtobrutinib dose by 50 mg. If the current pirtobrutinib dosage is 50 mg once daily, interrupt pirtobrutinib treatment for the duration of cobicistat use. Resume the previous dose of pirtobrutinib after cobicistat is discontinued for 5 half-lives. Pirtobrutinib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant with another strong CYP3A inhibitor increased pirtobrutinib overall exposure by 49%. (Moderate) Coadministration of tenofovir disoproxil fumarate with pirtobrutinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and pirtobrutinib is a P-gp and BCRP inhibitor.
Pitavastatin: (Major) The plasma concentrations of pitavastatin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as rhabdomyolysis or GI effects, is recommended during coadministration. Cobicistat is a organic anion transporting polypeptide (OATP) inhibitor, while pitavastatin is a OATP1B1 substrate.
Plazomicin: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as aminoglycosides. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and aminoglycosides are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Polatuzumab Vedotin: (Moderate) Monitor for increased polatuzumab vedotin toxicity during coadministration of cobicistat due to the risk of elevated exposure to the cytotoxic component of polatuzumab vedotin, MMAE. MMAE is metabolized by CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Strong CYP3A4 inhibitors are predicted to increase the exposure of MMAE by 45%.
Polymyxin B: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as polymyxin B. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Polysaccharide-Iron Complex: (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Ponatinib: (Major) Avoid coadministration of ponatinib and cobicistat due to the potential for increased ponatinib exposure. If concurrent use cannot be avoided, reduce the ponatinib dose to the next lower dose level (45 mg to 30 mg; 30 mg to 15 mg; 15 mg to 10 mg). If the patient is taking ponatinib 10 mg once daily prior to concurrent use, avoid the use of cobicistat and consider alternative therapy. After cobicistat has been discontinued for 3 to 5 half-lives, resume the dose of ponatinib that was tolerated prior to starting cobicistat. Ponatinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the ponatinib AUC by 78%.
Posaconazole: (Major) Caution is warranted when cobicistat is administered with posaconazole as there is a potential for elevated posaconazole and cobicistat concentrations. Posaconazole is a CYP3A4 inhibitor and a P-glycoprotein (P-gp) substrate. Cobicistat is an inhibitor of P-gp and a substrate of CYP3A4. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as posaconazole. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Pralsetinib: (Major) Avoid concomitant use of cobicistat and pralsetinib due to the risk of increased pralsetinib exposure which may increase the risk of adverse reactions. If concomitant use is necessary, reduce the dose of pralsetinib to 200 mg once daily for patients taking a daily dose of 400 mg or 300 mg, and to 100 mg once daily for patients taking a daily dose of 200 mg. Pralsetinib is a CYP3A and P-gp substrate and cobicistat is a combined strong CYP3A and P-gp inhibitor. Coadministration with a combined strong CYP3A and P-gp inhibitor is predicted to increase the overall exposure of pralsetinib by 251%.
Pravastatin: (Major) The plasma concentrations of pravastatin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as rhabdomyolysis or GI effects, is recommended during coadministration. Cobicistat is a organic anion transporting polypeptide (OATP) inhibitor, while pravastatin is a OATP1B1 substrate.
Prednisone: (Moderate) Coadministration of prednisone with cobicistat may cause elevated prednisone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor, while prednisone is a CYP3A4 and P-gp substrate. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
Pretomanid: (Moderate) Coadministration of tenofovir disoproxil fumarate with pretomanid may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and pretomanid is a P-gp and BCRP inhibitor.
Primidone: (Contraindicated) Coadministration of primidone with cobicistat-containing regimens is contraindicated. Primidone is converted to phenobarbital, a CYP3A4 inducer, while cobicistat is a substrate of CYP3A4. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy. (Major) Coadministration may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Primodine is converted to phenobarbital. Phenobarbital induces the CYP3A4 metabolism of elvitegravir. Consider an alternative anticonvulsant when using elvitegravir. The combination product cobicistat; elvitegravir; emtricitabine; tenofovir is contraindicated in combination with primidone as the concentrations of both elvitegravir and cobicistat may be significantly decreased.
Probenecid: (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent, such as probenecid; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Probenecid; Colchicine: (Major) Due to the risk for serious colchicine toxicity including multi-organ failure and death, avoid coadministration of colchicine and cobicistat in patients with normal renal and hepatic function unless the use of both agents is imperative. Coadministration is contraindicated in patients with renal or hepatic impairment because colchicine accumulation may be greater in these populations. Cobicistat can inhibit colchicine's metabolism via P-glycoprotein (P-gp) and CYP3A4, resulting in increased colchicine exposure. If coadministration in patients with normal renal and hepatic function cannot be avoided, adjust the dose of colchicine by either reducing the daily dose or the dosage frequency, and carefully monitor for colchicine toxicity. Specific dosage adjustment recommendations are available for the Colcrys product for patients who have taken a P-gp/strong CYP3A4 inhibitor like cobicistat in the past 14 days or require concurrent use: for prophylaxis of gout flares, if the original dose is 0.6 mg twice daily, decrease to 0.3 mg once daily or if the original dose is 0.6 mg once daily, decrease to 0.3 mg once every other day; for treatment of gout flares, give 0.6 mg as a single dose, then 0.3 mg 1 hour later, and do not repeat for at least 3 days; for familial Mediterranean fever, do not exceed a 0.6 mg/day. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent, such as probenecid; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Progesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with progesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. The metabolism of progesterone may also be inhibited by cobicistat, a strong inhibitor of the CYP3A4 hepatic enzyme. This interaction does not apply to vaginal preparations of progesterone (e.g., Crinone, Endometrin).
Promethazine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6.
Promethazine; Dextromethorphan: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
Promethazine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6.
Propafenone: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of propafenone with cobicistat. Propafenone is a substrate for CYP3A4 and a substrate and inhibitor of CYP2D6; cobicistat is a substrate and inhibitor of both these enzymes. Concurrent use may result in elevated propafe none plasma concentration. (Moderate) Coadministration of tenofovir disoproxil fumarate with propafenone may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and propafenone is a P-gp inhibitor.
Propranolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as propranolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as propranolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
Protriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Pyridoxine, Vitamin B6: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Quazepam: (Moderate) The plasma concentrations of quazepam may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS depression, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while quazepam is a CYP3A4 substrate.
Quetiapine: (Major) The plasma concentrations of quetiapine may be elevated when administered concurrently with cobicistat. The manufacturer of quetiapine recommends a quetiapine dose reduction to one-sixth the original dose during concurrent administration of CYP3A4 inhibitors, such as cobicistat. When cobicistat is discontinued, the dose should be increased by 6-fold.
Quinidine: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of quinidine with cobicistat. Quinidine is a substrate for CYP3A4 and P-glycoprotein (P-gp) and an inhibitor of CYP2D6 and P-gp; cobicistat is a substrate and inhibitor of both these enzymes and an inhibitor of P-gp. Concurrent use may result in elevated plasma concentration of both drugs. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as quinidine. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Quinine: (Major) Coadministration of elvitegravir with quinine is not recommended as there is a potential for altered elvitegravir concentrations and reduced quinine concentrations. Changes antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is a substrate of CYP3A4, and quinine may induce or inhibit CYP3A4. Elvitegravir also induces CYP2C9, and quinine is partially metabolized by CYP2C9. (Moderate) Concurrent administration of cobicistat with quinine may elevate the concentrations of both drugs; thereby increasing the potential for adverse events. CYP3A4 is the major enzyme responsible for quinine metabolism. Other isoenzymes, including CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP2E1, have some role in the metabolism of quinine; however, the extent of involvement of each of these differs depending on methodology used in the studies. Quinine is also a substrate of P-glycoprotein (P-gp) drug transporter. Cobicistat is a strong inhibitor of CYP3A4, and an inhibitor of CYP2D6 and P-gp. Quinine may inhibit CYP3A4, while cobicistat is metabolized by CYP3A4.
Quizartinib: (Major) Avoid concomitant use of cobicistat with quizartinib due to the risk of increased quizartinib exposure which may increase the risk of adverse reactions. If concomitant use is necessary, reduce the dose of quizartinib to 26.5 mg for patients taking a daily dose of 53 mg, and to 17.7 mg for patients taking a daily dose of 35.4 mg or 26.5 mg; interrupt quizartinib therapy for the duration of the strong CYP3A inhibitor use for patients already taking a daily dose of 17.7 mg. Quizartinib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the overall exposure of quizartinib by 94%.
Rabeprazole: (Minor) Use caution when administering cobicistat and rabeprazole concurrently. Cobicistat is an inhibitor of CYP3A and rabeprazole is partially metabolized by CYP3A. Co-administration can theoretically increase rabeprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
Ramelteon: (Moderate) Monitor for an increase in ramelteon-related adverse reactions if coadministration with cobicistat is necessary. Ramelteon is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ramelteon exposure by 84%.
Ranolazine: (Contraindicated) Concomitant use of ranolazine with cobicistat is contraindicated due to the potential for increased ranolazine plasma concentrations and therefore increased risk of QTc prolongation and possibly torsade de pointes. Ranolazine is a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-gp. Coadministration of another strong CYP3A4 inhibitor increased plasma concentrations of ranolazine by 220%. Serum concentrations of cobicistat could also be increased as ranolazine is a CYP3A4 and CYP2D6 inhibitor, and cobicistat is a CYP3A4 and CYP2D6 substrate. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as ranolazine. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Regorafenib: (Major) Avoid coadministration of regorafenib with cobicistat due to increased plasma concentrations of regorafenib and decreased plasma concentrations of the active metabolites M-2 and M-5, which may lead to increased toxicity. Regorafenib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased regorafenib exposure by 33% and decreased exposure of M-2 and M-5 by 93% each. (Moderate) Use caution if coadministration of regorafenib with tenofovir, PMPA is necessary, and monitor for an increase in tenofovir-related adverse reactions. Tenofovir is a BCRP substrate and regorafenib is a BCRP inhibitor. Regorafenib-mediated BCRP inhibition may increase exposure to tenofovir.
Relugolix: (Major) Avoid concomitant use of relugolix and oral cobicistat. Concomitant use may increase relugolix exposure and the risk of relugolix-related adverse effects. If concomitant use is unavoidable, administer cobicistat at least 6 hours after relugolix and monitor for adverse reactions. Relugolix is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor.
Relugolix; Estradiol; Norethindrone acetate: (Major) Avoid concomitant use of relugolix and oral cobicistat. Concomitant use may increase relugolix exposure and the risk of relugolix-related adverse effects. If concomitant use is unavoidable, administer cobicistat at least 6 hours after relugolix and monitor for adverse reactions. Relugolix is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor. (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Repaglinide: (Moderate) Coadministration of repaglinide and cobicistat may increase plasma concentrations of repaglinide; if coadministration is necessary, repaglinide dosage adjustment may be required and an increased frequency of glucose monitoring is recommended. Cobicistat is a strong CYP3A4 inhibitor and an inhibitor of organic anion transporting polypeptide (OATP). Repaglinide is a CYP3A4 and OATP1B1 substrate. Coadministration with other strong CYP3A4 inhibitors increased repaglinide exposure by up to 1.5-fold.
Retapamulin: (Moderate) Coadministration of retapamulin with strong CYP3A4 inhibitors, such as cobicistat, in patients younger than 24 months is not recommended. Systemic exposure of topically administered retapamulin may be higher in patients younger than 24 months than in patients 2 years and older. Retapamulin is a CYP3A4 substrate.
Revefenacin: (Major) Coadministration of revefenacin is not recommended with cobicistat because it could lead to an increase in systemic exposure of the active metabolite of revefenacin and an increased potential for anticholinergic adverse effects. The active metabolite of revefenacin is a substrate of OATP1B1 and OATP1B3; cobicistat is an inhibitor of OATP1B1 and OATP1B3.
Ribavirin: (Moderate) Use emtricitabine with ribavirin and interferon with caution and closely monitor for hepatic decompensation and anemia. Dose reduction or discontinuation of interferon, ribavirin, or both should be considered if worsening clinical toxicities are observed, including hepatic decompensation (e.g., Child-Pugh greater than 6). Hepatic decompensation (some fatal) has occurred in HCV/HIV coinfected patients who received both ribavirin/interferon and anti-retroviral nucleoside reverse transcriptase inhibitors (NRTIs) therapies.
Ribociclib: (Contraindicated) Coadministration of ribociclib with cobicistat is contraindicated, as elevated plasma concentrations of ribociclib may be associated with QT prolongation; exposure to cobicistat may also increase. Ribociclib is extensively metabolized by CYP3A4 and is a strong CYP3A4 inhibitor; cobicistat is a strong CYP3A4 inhibitor and CYP3A4 substrate. Coadministration of ribociclib with another strong inhibitor increased the ribociclib AUC and Cmax by 3.2-fold and 1.7-fold, respectively, in healthy volunteers.
Ribociclib; Letrozole: (Contraindicated) Coadministration of ribociclib with cobicistat is contraindicated, as elevated plasma concentrations of ribociclib may be associated with QT prolongation; exposure to cobicistat may also increase. Ribociclib is extensively metabolized by CYP3A4 and is a strong CYP3A4 inhibitor; cobicistat is a strong CYP3A4 inhibitor and CYP3A4 substrate. Coadministration of ribociclib with another strong inhibitor increased the ribociclib AUC and Cmax by 3.2-fold and 1.7-fold, respectively, in healthy volunteers.
Rifabutin: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. (Major) Coadministration of rifabutin with elvitegravir may result in reduced elvitegravir concentrations and elevated rifabutin concentrations. If these drugs must be used concurrently, reduce the dose of rifabutin by at least 75% of the usual 300 mg/day dose (e.g., 150 mg every other day or 3x/week). If the rifabutin dose is reduced, no dose adjustment is required for elvitegravir. Monitor closely for rifabutin-associated adverse events.
Rifampin: (Contraindicated) Coadministration of rifampin with cobicistat is contraindicated. Rifampin induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Coadministration of rifampin, a potent CYP3A4 inducer, with elvitegravir, a CYP3A4 substrate, is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance.
Rifapentine: (Major) Coadministration of cobicistat and rifapentine is not recommended as concurrent use may result in significant decreases in the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is a CYP3A4 substrate and rifapentine is a strong CYP3A4 inducer. (Major) Coadministration of elvitegravir with rifapentine is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is metabolized by CYP3A4 and rifapentine is a strong CYP3A4 inducer.
Rifaximin: (Moderate) Monitor for an increase in rifaximin-related adverse reactions if coadministration with cobicistat is necessary. Concomitant use may increase rifaximin exposure. In patients with hepatic impairment, a potential additive effect of reduced metabolism may further increase systemic rifaximin exposure. Rifaximin is a P-gp substrate and cobicistat is a P-gp inhibitor. Coadministration with another P-gp inhibitor increased rifaximin overall exposure by 124-fold.
Rilpivirine: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
Rimegepant: (Major) Avoid coadministration of rimegepant with cobicistat; concurrent use may significantly increase rimegepant exposure. Rimegepant is a CYP3A4 and P-gp substrate and cobicistat is a strong CYP3A4 inhibitor and a P-gp inhibitor. Coadministration of rimegepant with another strong CYP3A4 inhibitor increased rimegepant exposure by 4-fold.
Ripretinib: (Moderate) Monitor patients more frequently for ripretinib-related adverse reactions if coadministered with cobicistat. Coadministration may increase the exposure of ripretinib and its active metabolite (DP-5439), which may increase the risk of adverse reactions. Ripretinib and DP-5439 are metabolized by CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ripretinib and DP-5439 exposure by 99%.
Risperidone: (Major) Coadministration of risperidone, a CYP2D6 substrate, and cobicistat, a potent CYP2D6 inhibitor, may increase plasma concentrations of risperidone. When oral risperidone is given with a potent CYP2D6 inhibitor, the dose of risperidone should not exceed 8 mg/day PO in adults. When initiating therapy, titrate risperidone slowly. Upon discontinuation of the CYP2D6 inhibitor, the risperidone dose should be re-evaluated and increased if necessary. For the long-acting risperidone injection, the current adult dosage should be closely monitored when a potent CYP2D6 inhibitor is initiated or discontinued. An adjustment of the dose may be required.
Ritlecitinib: (Moderate) Monitor for cobicistat-related adverse effects if coadministered with ritlecitinib as concurrent use may increase cobicistat exposure. Cobicistat is a CYP3A substrate and ritlecitinib is a moderate CYP3A inhibitor.
Ritonavir: (Contraindicated) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrate, concurrently with inhibitors of P-gp and BCRP, such as ritonavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions. (Moderate) Concurrent administration of elvitegravir with ritonavir may result in elevated elvitegravir plasma concentrations. Elvitegravir is a substrate of the hepatic isoenzyme CYP3A4. Ritonavir inhibits the CYP3A4 enzyme. Caution and close monitoring are advised if these drugs are administered together.
Rivaroxaban: (Major) Avoid concomitant administration of rivaroxaban and cobicistat; significant increases in rivaroxaban exposure may increase bleeding risk. Rivaroxaban is a substrate of CYP3A4/5 and the P-glycoprotein (P-gp) transporter. Cobicistat is a combined P-gp and strong CYP3A4 inhibitor. Concurrent use of a single dose of rivaroxaban and another combined P-gp and strong CYP3A4 inhibitor increased the steady-state rivaroxaban AUC and Cmax by 150% and 60%, respectively. Similar increases in pharmacodynamic effects such as factor Xa inhibition and PT prolongation were also observed.
Roflumilast: (Moderate) Monitor for an increase in roflumilast-related adverse reactions if concomitant use with cobicistat is necessary. Concurrent use may increase roflumilast exposure. Roflumilast is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the exposure of roflumilast by 99%.
Rolapitant: (Major) Use caution if cobicistat and rolapitant are used concurrently, and monitor for cobicistat-related adverse effects. Cobicistat is a CYP2D6 substrate and rolapitant is a moderate CYP2D6 inhibitor; the inhibitory effect of rolapitant is expected to persist beyond 28 days for an unknown duration. Exposure to another CYP2D6 substrate, following a single dose of rolapitant increased about 3-fold on Days 8 and Day 22. The inhibition of CYP2D6 persisted on Day 28 with a 2.3-fold increase in the CYP2D6 substrate concentrations, the last time point measured. (Moderate) Use caution if tenofovir, PMPA and rolapitant are used concurrently, and monitor for tenofovir-related adverse effects. Tenofovir is a substrate of the Breast Cancer Resistance Protein (BCRP) and P-glycoprotein (P-gp), where an increase in exposure may significantly increase adverse effects; rolapitant is a BCRP and P-gp inhibitor. The Cmax and AUC of another BCRP substrate, sulfasalazine, were increased by 140% and 130%, respectively, on day 1 with rolapitant, and by 17% and 32%, respectively, on day 8 after rolapitant administration. When rolapitant was administered with digoxin, a P-gp substrate, the day 1 Cmax and AUC were increased by 70% and 30%, respectively; the Cmax and AUC on day 8 were not studied.
Romidepsin: (Moderate) Monitor for toxicity related to increased romidepsin exposure and follow the dose modifications for toxicity during initial administration of romidepsin with cobicistat. Romidepsin is a CYP3A4 and P-gp substrate; cobicistat is a P-gp inhibitor and strong CYP3A4 inhibitor. In a pharmacokinetic drug interaction trial a strong CYP3A4 inhibitor increased romidepsin AUC by approximately 25%.
Ropivacaine: (Moderate) The plasma concentrations of ropivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as hypotension, bradycardia or GI effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while ropivacaine is a CYP3A4 substrate.
Rosiglitazone: (Minor) Plasma concentrations of rosiglitazone may be decreased when administered concurrently with elvitegravir. Patients may experience a decreased hypoglycemic effect when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while rosiglitazone is a CYP2C9 substrate.
Rosuvastatin: (Major) Avoid concurrent administration of cobicistat and rosuvastatin. Taking these drugs together results in elevated rosuvastatin concentrations. If these drugs must be used together, use the lowest starting dose of rosuvastatin and carefully titrate while monitoring for adverse events (myopathy). Rosuvastatin is taken up into human hepatocytes mainly by organic anion transporting polypeptide (OATP)1B1 and OATP1B3. Cobicistat is an inhibitor of OATP. (Moderate) Caution is warranted when elvitegravir is administered with rosuvastatin as there is a potential for decreased rosuvastatin concentrations. Alternatively, when elvitegravir is boosted with cobicistat, the concentration of rosuvastatin may be increased due to inhibition of OATP by cobicistat. In one pharmacokinetic study, the Cmax and AUC of rosuvastatin were increased by 89% and 38%, respectively, when given concurrently with cobicistat and elvitegravir. Patients may experience a decreased antilipemic effect elvitegravir and rosuvastatin are coadministered. If elvitegravir is boosted with cobicistat, patients may be at increased risk for side effects of rosuvastatin. Rosuvastatin is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Rosuvastatin; Ezetimibe: (Major) Avoid concurrent administration of cobicistat and rosuvastatin. Taking these drugs together results in elevated rosuvastatin concentrations. If these drugs must be used together, use the lowest starting dose of rosuvastatin and carefully titrate while monitoring for adverse events (myopathy). Rosuvastatin is taken up into human hepatocytes mainly by organic anion transporting polypeptide (OATP)1B1 and OATP1B3. Cobicistat is an inhibitor of OATP. (Moderate) Caution is warranted when elvitegravir is administered with rosuvastatin as there is a potential for decreased rosuvastatin concentrations. Alternatively, when elvitegravir is boosted with cobicistat, the concentration of rosuvastatin may be increased due to inhibition of OATP by cobicistat. In one pharmacokinetic study, the Cmax and AUC of rosuvastatin were increased by 89% and 38%, respectively, when given concurrently with cobicistat and elvitegravir. Patients may experience a decreased antilipemic effect elvitegravir and rosuvastatin are coadministered. If elvitegravir is boosted with cobicistat, patients may be at increased risk for side effects of rosuvastatin. Rosuvastatin is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Ruxolitinib: (Major) Reduce the ruxolitinib dosage when coadministered with cobicistat in patients with myelofibrosis (MF) or polycythemia vera (PV) as increased ruxolitinib exposure and toxicity may occur. No dose adjustments are necessary for patients with graft-versus-host disease; however, monitor blood counts more frequently for toxicity and adjust ruxolitinib dosage for adverse reactions. In MF patients, reduce the initial dose to 10 mg PO twice daily for platelet count of 100,000 cells/mm3 or more and 5 mg PO once daily for platelet count of 50,000 to 99,999 cells/mm3. In PV patients, reduce the initial dose to 5 mg PO twice daily. In MF or PV patients stable on ruxolitinib dose of 10 mg PO twice daily or more, reduce dose by 50%; in patients stable on ruxolitinib dose of 5 mg PO twice daily, reduce ruxolitinib to 5 mg PO once daily. Avoid the use of cobicistat in MF or PV patients who are stable on a ruxolitinib dose of 5 mg PO once daily. Ruxolitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Sacubitril; Valsartan: (Moderate) Caution is warranted when elvitegravir is administered with valsartan as there is a potential for decreased valsartan concentrations. Valsartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
Salicylates: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Salmeterol: (Major) Avoid concomitant use of salmeterol with cobicistat. Concomitant use increases salmeterol exposure and may increase the incidence and severity of salmeterol-related adverse effects. Signs and symptoms of excessive beta-adrenergic stimulation commonly include tachyarrhythmias, hypertension, and tremor. Salmeterol is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased salmeterol overall exposure 16-fold mainly due to increased bioavailability of the swallowed portion of the dose.
Salsalate: (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents, like salicylates should be carefully monitored for changes in serum creatinine and phosphorus.
Saquinavir: (Contraindicated) Use of saquinavir with cobicistat plus either atazanavir or darunavir is not recommended, as pharmacokinetic data are not available to provide appropriate dosage recommendations. Saquinavir is a substrate/inhibitor of CYP3A4 and P-glycoprotein (P-gp) substrate, cobicistat is a substrate/inhibitor of CYP3A4 as well as an inhibitor of P-gp, and atazanavir and darunavir are CYP3A4 substrates. (Major) Avoid coadministration of saquinavir with elvitegravir. No data are available regarding use of these drugs concurrently. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as saquinavir. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Saxagliptin: (Major) Limit the dose of saxagliptin to 2.5 mg PO once daily when administered with cobicistat due to significantly increased saxagliptin exposure. Saxagliptin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 100 mg dose of saxagliptin and a single 20 mg dose of saxagliptin increased the saxagliptin AUC by 2.45-fold and 3.67-fold, respectively.
Segesterone Acetate; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with segesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns. (Moderate) Consider the benefits and risk of administering elvitegravir with ethinyl estradiol; norgestimate and other combination oral contraceptives. Concurrent use may result in elevated norgestimate and reduced ethinyl estradiol serum concentrations. Risk associated with these altered concentrations may include increased insulin resistance, dyslipidemia, acne, and venous thrombosis. Consider alternative non-hormonal methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS.
Selective serotonin reuptake inhibitors: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Selpercatinib: (Major) Avoid coadministration of selpercatinib and cobicistat due to the risk of increased selpercatinib exposure which may increase the risk of adverse reactions, including QT prolongation. If coadministration is unavoidable, reduce the dose of selpercatinib to 40 mg PO twice daily if original dose was 120 mg twice daily, and to 80 mg PO twice daily if original dose was 160 mg twice daily. Monitor ECGs for QT prolongation more frequently. If cobicistat is discontinued, resume the original selpercatinib dose after 3 to 5 elimination half-lives of cobicistat. Selpercatinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased selpercatinib exposure by 133%. (Moderate) Coadministration of tenofovir disoproxil fumarate with selpercatinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and selpercatinib is a P-gp inhibitor.
Selumetinib: (Major) Avoid coadministration of selumetinib and cobicistat due to the risk of increased selumetinib exposure which may increase the risk of adverse reactions. If coadministration is unavoidable, reduce the dose of selumetinib to 20 mg/m2 PO twice daily if original dose was 25 mg/m2 twice daily and 15 mg/m2 PO twice daily if original dose was 20 mg/m2 twice daily. If cobicistat is discontinued, resume the original selumetinib dose after 3 elimination half-lives of cobicistat. Selumetinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased selumetinib exposure by 49%.
Sertraline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
Sildenafil: (Major) Sildenafil is contraindicated for use with cobicistat when used for pulmonary arterial hypertension (PAH). If used for erectile dysfunction, the dose of sildenafil should not exceed 25 mg in 48 hours with increased monitoring for adverse reactions during times of coadministration. Concurrent use is expected to substantially increase the sildenafil plasma concentrations and may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection. Sildenafil is a sensitive CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of other strong CYP3A4 inhibitors increased the sildenafil AUC between 3- and 11-fold.
Silodosin: (Contraindicated) Concurrent use of silodosin and cobicistat is contraindicated due to increased plasma concentrations of silodosin resulting in an increase of treatment-related adverse reactions. Cobicistat is a strong inhibitor of CYP3A4 and a P-glycoprotein (P-gp) inhibitor. Silodosin is a CYP3A4 and P-gp substrate. Coadministration with another strong CYP3A4 inhibitor increased silodosin exposure by 2.9-fold to 3.2-fold.
Simvastatin: (Contraindicated) Concomitant use of simvastatin with cobicistat is contraindicated due to increased simvastatin exposure and potential for myopathy, including rhabdomyolysis. Simvastatin is a substrate for CYP3A4; cobicistat is a strong CYP3A4 inhibitor.
Siponimod: (Moderate) Concomitant use of siponimod and cobicistat may increase siponimod exposure. If the patient is also receiving a drug regimen containing a moderate CYP2C9 inhibitor, use of siponimod is not recommended due to a significant increase in siponimod exposure. Siponimod is a CYP2C9 and CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with a moderate CYP2C9/CYP3A4 dual inhibitor led to a 2-fold increase in the exposure of siponimod.
Sirolimus: (Major) Avoid concomitant use of sirolimus and cobicistat. Coadministration may increase sirolimus concentrations and increase the risk for sirolimus-related adverse effects. Sirolimus is a CYP3A and P-gp substrate and cobicistat is a strong CYP3A and P-gp inhibitor. Concomitant use of another strong CYP3A and P-gp inhibitor increased sirolimus overall exposure by 10.9-fold.
Sodium Bicarbonate: (Moderate) Separate administration of elvitegravir and antacids by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Sodium Ferric Gluconate Complex; ferric pyrophosphate citrate: (Moderate) Separate administration of elvitegravir and iron by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Sodium Phenylbutyrate; Taurursodiol: (Major) Avoid coadministration of sodium phenylbutyrate; taurursodiol and cobicistat. Concomitant use may increase plasma concentrations of sodium phenylbutyrate; taurursodiol. Sodium phenylbutyrate; taurursodiol is an OATP1B3 substrate and cobicistat is an OATP1B3 inhibitor. (Moderate) Coadministration of tenofovir disoproxil fumarate with taurursodiol may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and taurursodiol is a P-gp and BCRP inhibitor.
Sofosbuvir: (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP.
Sofosbuvir; Velpatasvir: (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP. (Moderate) Monitor for velpatasvir-related adverse events when administering velpatasvir with cobicistat. In an interaction study, use of these drugs together resulted in a 50% increase in velpatasvir exposure; however, because data have not correlated velpatasvir exposure with toxicity, no dose adjustments are recommended. Velpatasvir is a substrate of P-glycoprotein (P-gp), organic anion transporting polypeptide (OATP1B1), Breast Cancer Resistance Protein (BCRP), and CYP3A; cobistat is an inhibitor of P-gp, OATP1B1, BCRP, and CYP3A4. (Moderate) Monitor patients for tenofovir-associated adverse reactions, such as renal toxicity, in patients receiving regimens containing tenofovir disoproxil fumarate and velpatasvir due to potential increases in tenofovir serum concentrations. When administered concurrently with velpatasvir, the peak concentration (Cmax), systemic exposure (AUC), and the trough concentration (Cmin) of tenofovir increased by 44%, 40%, and 84%, respectively. Tenofovir is a substrate of the breast cancer resistance protein (BCRP) and P-glycoprotein (P-gp) transporters, while velpatasvir inhibits both BCRP and P-gp. Consider use of tenofovir alafenamide in place of tenofovir disoproxil fumarate.
Sofosbuvir; Velpatasvir; Voxilaprevir: (Major) Avoid concurrent administration of voxilaprevir with tenofovir disoproxil fumarate. Taking these medications together may increase tenofovir plasma concentrations, potentially increasing the risk for adverse events. Tenofovir disoproxil fumarate is a substrate for the drug transporter Breast Cancer Resistance Protein (BCRP). Voxilaprevir is a BCRP inhibitor. (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP. (Moderate) Monitor for velpatasvir-related adverse events when administering velpatasvir with cobicistat. In an interaction study, use of these drugs together resulted in a 50% increase in velpatasvir exposure; however, because data have not correlated velpatasvir exposure with toxicity, no dose adjustments are recommended. Velpatasvir is a substrate of P-glycoprotein (P-gp), organic anion transporting polypeptide (OATP1B1), Breast Cancer Resistance Protein (BCRP), and CYP3A; cobistat is an inhibitor of P-gp, OATP1B1, BCRP, and CYP3A4. (Moderate) Monitor patients for tenofovir-associated adverse reactions, such as renal toxicity, in patients receiving regimens containing tenofovir disoproxil fumarate and velpatasvir due to potential increases in tenofovir serum concentrations. When administered concurrently with velpatasvir, the peak concentration (Cmax), systemic exposure (AUC), and the trough concentration (Cmin) of tenofovir increased by 44%, 40%, and 84%, respectively. Tenofovir is a substrate of the breast cancer resistance protein (BCRP) and P-glycoprotein (P-gp) transporters, while velpatasvir inhibits both BCRP and P-gp. Consider use of tenofovir alafenamide in place of tenofovir disoproxil fumarate.
Solifenacin: (Major) If coadministered with cobicistat, do not exceed a 5 mg daily dose of solifenacin in adults; do not exceed the initial starting dose in pediatric patients. The plasma concentrations of solifenacin may be elevated when administered concurrently with cobicistat. Monitor for excessive anticholinergic effects. Solifenacin is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased solifenacin exposure by 2.7-fold.
Sonidegib: (Major) Avoid concomitant use of sonidegib and cobicistat as increased sonidegib plasma are expected, resulting in an increased risk of adverse events, particularly musculoskeletal toxicity. Cobicistat is a strong CYP3A4 inhibitor and may significantly increase the level of the CYP3A4 substrate, sonidegib. Coadministration of another strong CYP3A4 inhibitor increased the mean Cmax and AUC of sonidegib by 2.2-fold and 1.5-fold, respectively.
Sorafenib: (Moderate) Monitor for an increase in tenofovir-related adverse reactions if coadministration with sorafenib is necessary. Tenofovir is a P-glycoprotein (P-gp) substrate and sorafenib inhibits P-gp in vitro. Sorafenib may increase the concentrations of concomitantly administered drugs that are P-gp substrates.
Sotorasib: (Moderate) Coadministration of cobicistat with sotorasib may result in decreased plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is a CYP3A4 substrate and sotorasib is a moderate CYP3A4 inducer. (Moderate) Coadministration of elvitegravir with sotorasib may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Elvitegravir is a CYP3A4 substrate and sotorasib is a moderate CYP3A4 inducer. (Moderate) Coadministration of tenofovir disoproxil fumarate with sotorasib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and sotorasib is a P-gp and BCRP inhibitor.
Sparsentan: (Major) Avoid concomitant use of sparsentan and cobicistat. Concomitant use may increase sparsentan exposure and the risk for sparsentan-related adverse effects. Sparsentan is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use with another strong CYP3A inhibitor increased sparsentan overall exposure by 174%. (Moderate) Coadministration of tenofovir disoproxil fumarate with sparsentan may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp and BCRP substrate and sparsentan is a P-gp and BCRP inhibitor.
St. John's Wort, Hypericum perforatum: (Contraindicated) Coadministration of St. John's Wort, Hypericum perforatum with cobicistat is contraindicated. St. John's Wort induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. St. John's Wort in all forms, including teas, should be avoided. (Major) Coadministration of St. John's Wort, Hypericum perforatum with elvitegravir is not recommended. St. John's Wort induces CYP3A4; elvitegravir is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of elvitegravir, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. St. John's Wort in all forms, including teas, should be avoided.
Streptogramins: (Moderate) Caution is warranted when cobicistat is administered with dalfopristin; quinupristin as there is a potential for elevated cobicistat concentrations. Quinupristin is a CYP3A4 inhibitor and cobicistat is substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with dalfopristin; quinupristin as there is a potential for elevated elvitegravir concentrations. Quinupristin is a CYP3A4 inhibitor and elvitegravir is a substrate of CYP3A4.
Streptomycin: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as aminoglycosides. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and aminoglycosides are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Sucralfate: (Moderate) Separate administration of elvitegravir and sucralfate by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Sufentanil: (Moderate) Because the dose of the sufentanil sublingual tablets cannot be titrated, consider an alternate opiate if cobicistat must be administered. Consider a reduced dose of sufentanil injection with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the sufentanil injection dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Sufentanil is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase sufentanil exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of sufentanil. If cobicistat is discontinued, sufentanil plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to sufentanil.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Moderate) Caution is warranted when elvitegravir is administered with sulfamethoxazole; trimethoprim, SMX-TMP as there is a potential for decreased sulfamethoxazole concentrations. Sulfamethoxazole is a substrate of CYP2C9, while elvitegravir is a CYP2C9 inducer.
Sulindac: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Sumatriptan; Naproxen: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions. (Moderate) The plasma concentrations of naproxen may be decreased when administered concurrently with elvitegravir. Patients may experience decreased analgesic or anti-inflammatory effects when these drugs are coadministered. Elvitegravir is a CYP2C9 inducer, while naproxen is a CYP2C9 substrate.
Sunitinib: (Major) Avoid coadministration of cobicistat with sunitinib if possible due to increased sunitinib exposure, which may increase the risk of QT prolongation. If concomitant use is unavoidable, monitor the QT interval more frequently and consider reducing the daily dose of sunitinib to a minimum of 37.5 mg for patients with GIST or RCC, and to a minimum of 25 mg for patients with pNET. Sunitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased exposure to sunitinib and its primary active metabolite by 51%.
Suvorexant: (Major) Coadministration of suvorexant and cobicistat is not recommended due to the potential for significantly increased suvorexant exposure. Suvorexant is a CYP3A4 substrate. Cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the suvorexant AUC by 2.8-fold.
Tacrolimus: (Major) Decrease tacrolimus dose and closely monitor tacrolimus serum concentrations if coadministration with cobicistat is necessary; additional dosage reductions may be required. Concurrent use may increase tacrolimus serum concentrations and increase the risk of toxicity. Tacrolimus is a sensitive CYP3A4 substrate with a narrow therapeutic range; cobicistat is a strong CYP3A4 inhibitor. (Major) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent, including tacrolimus. (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered with tacrolimus. Consider the potential for drug interaction prior to and during concurrent use of these medications. Medications that decrease renal function, such as tacrolimus, may increase concentrations of emtricitabine; as emtricitabine is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion.
Tadalafil: (Major) Avoid coadministration of tadalafil and cobicistat for the treatment of pulmonary hypertension. For the treatment of erectile dysfunction, do not exceed 10 mg tadalafil within 72 hours of cobicistat for the 'as needed' dose or 2.5 mg daily for the 'once-daily' dose. Tadalafil is metabolized predominantly by CYP3A. Potent inhibitors of CYP3A, such as cobicistat, may reduce tadalafil clearance. Increased systemic exposure to tadalafil may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection.
Tafamidis: (Moderate) Caution is advised with the coadministration of tafamidis and tenofovir disoproxil fumarate due to the potential for increased plasma concentrations of tenofovir disoproxil fumarate increasing the risk of adverse effects. Tenofovir disoproxil fumarate dose adjustment may be needed with coadministration. Tenofovir disoproxil fumarate is a substrate of breast cancer resistance protein (BCRP) and tafamidis is a BCRP inhibitor.
Talazoparib: (Moderate) Monitor for an increase in talazoparib-related adverse reactions if concomitant use of cobicistat is necessary. Concomitant use may increase talazoparib exposure. Talazoparib is a P-gp and BCRP substrate; cobicistat is a P-gp and BCRP inhibitor.
Talimogene Laherparepvec: (Major) Consider the risks and benefits of treatment with talimogene laherparepvec before administering acyclovir or other antivirals to prevent or manage herpetic infection. Talimogene laherparepvec is a live, attenuated herpes simplex virus that is sensitive to acyclovir; coadministration with antiviral agents may cause a decrease in efficacy.
Tamsulosin: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively.
Tazemetostat: (Major) Avoid coadministration of tazemetostat with cobicistat as concurrent use may increase tazemetostat exposure and the frequency and severity of adverse reactions. Tazemetostat is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration of a moderate CYP3A4 inhibitor increased tazemetostat exposure by 3.1-fold.
Tedizolid: (Moderate) Coadministration of tenofovir disoproxil fumarate with tedizolid may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a BCRP substrate and tedizolid is a BCRP inhibitor.
Telmisartan; Amlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
Temsirolimus: (Major) Avoid coadministration of cobicistat with temsirolimus due to increased plasma concentrations of the primary active metabolite of temsirolimus (sirolimus). If concomitant use is unavoidable, consider reducing the dose of temsirolimus to 12.5 mg per week. Allow a washout period of approximately 1 week after discontinuation of cobicistat before increasing temsirolimus to its original dose. Temsirolimus is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor did not significantly affect temsirolimus exposure, but increased the AUC and Cmax of sirolimus by 3.1-fold and 2.2-fold, respectively. (Moderate) Monitor for an increase in tenofovir disoproxil fumarate-related adverse reactions if coadministration with temsirolimus is necessary. Tenofovir disoproxil fumarate is a P-glycoprotein (P-gp) substrate and temsirolimus is a P-gp inhibitor. Concomitant use may lead to increased concentrations of tenofovir disoproxil fumarate.
Teniposide: (Major) The plasma concentrations of teniposide may be significantly elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as myelosuppression, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor, while teniposide is a CYP3A4 and P-gp substrate.
Tenofovir Alafenamide: (Moderate) The plasma concentrations of tenofovir may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the drug transporters P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and organic anion transport protein (OATP1B1/1B3). Tenofovir alafenamide is a substrate for all three transporters.
Tepotinib: (Moderate) Coadministration of tenofovir disoproxil fumarate with tepotinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and tepotinib is a P-gp inhibitor.
Terbinafine: (Moderate) Caution is advised when administering terbinafine with cobicistat. Although this interaction has not been studied by the manufacturer, and published literature suggests the potential for interactions to be low, taking these drugs together may alter the systemic exposure of both drugs. Predictions about the interaction can be made based on the metabolic pathways of both drugs. Terbinafine is an inhibitor of CYP2D6 and is metabolized by at least 7 CYP isoenyzmes, with major contributions coming from CYP3A4. Cobicistat is a substrate of CYP2D6 and an inhibitor of CYP3A4. Monitor patients for adverse reactions if these drugs are coadministered. Topical terbinafine formulations would not be expected to interact. (Moderate) Caution is advised when administering terbinafine with elvitegravir. Although this interaction has not been studied by the manufacturer, and published literature suggests the potential for interactions to be low, taking these drugs together may lower the systemic exposure of terbinafine. Predictions about the interaction can be made based on the metabolic pathways of both drugs. Terbinafine is metabolized by at least 7 CYP isoenyzmes, with major contributions coming from CYP2C9. Elvitegravir is an inducer of CYP2C9. Monitor patients for breakthrough fungal infections if these drugs are coadministered.
Tetrabenazine: (Moderate) The plasma concentrations of tetrabenazine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while tetrabenazine is a CYP2D6 substrate.
Tezacaftor; Ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Coadministration is not recommended in patients younger than 6 months. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. (Major) Reduce the dosing frequency of tezacaftor; ivacaftor when coadministered with cobicistat; coadministration may increase tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 1 tezacaftor/ivacaftor combination tablet twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate); cobicistat is a strong CYP3A inhibitor. Coadministration of a strong CYP3A inhibitor increased tezacaftor and ivacaftor exposure 4- and 15.6-fold, respectively. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as ivacaftor. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Theophylline, Aminophylline: (Moderate) Caution is warranted when cobicistat is administered with theophylline; aminophylline as there is a potential for elevated theophylline concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Theophylline is a substrate of CYP3A4; cobicistat is a CYP3A4 inhibitor.
Thioridazine: (Contraindicated) Cobicistat is a mild inhibitor of CYP2D6 and the use of thioridazine concomitantly with CYP2D6 inhibitors is contraindicated due to the possible risk of QT prolongation and subsequent arrhythmias, or other serious side effects, occurring from elevated serum concentrations of thioridazine.
Thiotepa: (Major) Avoid the concomitant use of thiotepa and cobicistat if possible; reduced metabolism to the active thiotepa metabolite may result in decreased thiotepa efficacy. Consider an alternative agent with no or minimal potential to inhibit CYP3A4. If coadministration is necessary, monitor patients for signs of reduced thiotepa efficacy. In vitro, thiotepa is metabolized via CYP3A4 to the active metabolite, TEPA; cobicistat is a strong CYP3A4 inhibitor.
Tiagabine: (Moderate) The plasma concentrations of tiagabine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while tiagabine is a CYP3A4 substrate.
Ticagrelor: (Major) Avoid coadministration of ticagrelor with cobicistat due to increased plasma concentrations of ticagrelor resulting in an increased risk of dyspnea, bleeding, and other treatment-related adverse reactions. Ticagrelor is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ticagrelor exposure by 7.32-fold. (Moderate) Caution is advised when administering tenofovir, PMP A, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as ticagrelor. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Timolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as timolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
Tinidazole: (Moderate) The plasma concentrations of tinidazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while tinidazole is a CYP3A4 substrate.
Tipranavir: (Contraindicated) Use of tipranavir with cobicistat plus either atazanavir or darunavir is not recommended, as pharmacokinetic data are not available to provide appropriate dosage recommendations. Use of tipranavir with either atazanavir; cobicistat or darunavir; cobicistat may lead to loss of antiretroviral efficacy and development of resistance. Tipranavir is a substrate/inhibitor of CYP3A4, an inhibitor of CYP2D6, and a substrate of P-glycoprotein (P-gp). Cobicistat is a substrate/inhibitor of both CYP2D6 and CYP3A4 as well as an inhibitor of P-gp, and atazanavir and darunavir are CYP3A4 substrates. (Moderate) Coadministration of tipranavir boosted with ritonavir and elvitagravir results in an unknown effect on the plasma concentrations of elvitegravir. The recommended dosing regimen for these drugs used in combination is: elvitegravir 150 mg PO once daily with tipranavir/ritonavir 500/200 mg PO twice daily. No data are available for use of other dosage. (Moderate) Concurrent administration of tipranavir and ritonavir with tenofovir, results in decreased tipranavir concentrations. The clinical significance of this interaction has not been established, and no recommendations for tenofovir dosage adjustments are available.
Tisotumab Vedotin: (Moderate) Monitor for tisotumab vedotin-related adverse reactions if concomitant use with cobicistat is necessary due to increased monomethyl auristatin E (MMAE) exposure which may increase the incidence and severity of adverse reactions. MMAE, the active component of tisotumab vedotin, is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Clinical drug interaction studies have not been conducted for tisotumab vedotin. However, coadministration of another antibody-drug conjugate that contains MMAE with a strong CYP3A inhibitor increased unconjugated MMAE exposure by 34%.
Tobramycin: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as aminoglycosides. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and aminoglycosides are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Moderate) Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus.
Tofacitinib: (Major) A dosage reduction of tofacitinib is necessary if coadministered with cobicistat. In patients receiving 5 mg or less twice daily, reduce to once daily dosing; in patients receiving 10 mg twice daily, reduce to 5 mg twice daily; in patients receiving 22 mg once daily of the extended-release (XR) formulation, switch to 11 mg XR once daily; in patients receiving 11 mg XR once daily, switch to the immediate-release formulation at a dose of 5 mg once daily. Tofacitinib exposure is increased when coadministered with cobicistat. Cobicistat is a strong CYP3A4 inhibitor; tofacitinib is a CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased tofacitinib exposure by 2-fold.
Tolmetin: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Tolterodine: (Major) Reduce the dose of immediate-release tolterodine to 1 mg twice daily and extended-release tolterodine to 2 mg once daily if coadministered with cobicistat. Concurrent use may increase tolterodine exposure. Cobicistat is a strong CYP3A4 inhibitor. In CYP2D6 poor metabolizers, the CYP3A4 pathway becomes important in tolterodine elimination. Because it is difficult to assess which patients will be poor CYP2D6 metabolizers, reduced doses of tolterodine are advised when administered with strong CYP3A4 inhibitors. In a drug interaction study, coadministration of a strong CYP3A4 inhibitor increased the tolterodine AUC by 2.5-fold in CYP2D6 poor metabolizers.
Tolvaptan: (Contraindicated) The concomitant use of tolvaptan and cobicistat is contraindicated. Concurrent use is expected to increase tolvaptan exposure. Tolvaptan is a sensitive CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Coadministration of another strong CYP3A4 inhibitor increased tolvaptan exposure 5-fold. No data exists regarding the appropriate dose adjustment needed to allow safe administration of tolvaptan with strong CYP3A4 inhibitors.
Topiramate: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with topiramate as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Elvitegravir is a CYP3A4 substrate.
Topotecan: (Major) Avoid coadministration of cobicistat with oral topotecan due to increased topotecan exposure; cobicistat may be administered with intravenous topotecan. Oral topotecan is a substrate of P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP); cobicistat is a P-gp and BCRP inhibitor. Following escalating doses of a dual inhibitor of BCRP and P-gp, the AUC of topotecan lactone and total topotecan increased by approximately 2.5-fold compared to topotecan alone. Coadministration of a dual P-gp/BCRP inhibitor with intravenous topotecan increased total topotecan exposure by 1.2-fold and exposure to topotecan lactone by 1.1-fold.
Toremifene: (Major) Avoid coadministration of cobicistat with toremifene if possible due to increased plasma concentrations of toremifene which may result in QT prolongation. If concomitant use is unavoidable, closely monitor ECGs for QT prolongation and monitor electrolytes; correct hypokalemia or hypomagnesemia prior to administration of toremifene. Toremifene is a CYP3A4 substrate that has been shown to prolong the QTc interval in a dose- and concentration-related manner, and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased toremifene exposure by 2.9-fold; exposure to N-demethyltoremifene was reduced by 20%.
Trabectedin: (Major) Avoid the concomitant use of trabectedin with cobicistat due to the risk of increased trabectedin exposure. Trabectedin is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the systemic exposure of a single dose of trabectedin (0.58 mg/m2 IV) by 66% compared to a single dose of trabectedin (1.3 mg/m2) given alone.
Tramadol: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
Tramadol; Acetaminophen: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
Trandolapril; Verapamil: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as verapamil, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate dose reductions are advised. (Moderate) Coadministration of tenofovir disoproxil fumarate with verapamil may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and verapamil is a P-gp inhibitor.
Trazodone: (Major) Avoid coadministration of trazodone with cobicistat due to the potential for increased trazodone exposure and associated adverse effects including QT prolongation. If concurrent use cannot be avoided, consider a reduced dose of trazodone based on tolerability. Trazodone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of other strong CYP3A4 inhibitors increased the exposure of trazodone compared to the use of trazodone alone.
Triamcinolone: (Moderate) Cobicistat may inhibit the CYP3A4 metabolism of triamcinolone, resulting in increased plasma triamcinolone concentrations and reduced serum cortisol concentrations. There have been reports of clinically significant drug interactions in patients receiving another strong CYP3A4 inhibitor with triamcinolone, resulting in systemic corticosteroid effects including, but not limited to, Cushing syndrome and adrenal suppression. Consider the benefit-risk of concomitant use and monitor for systemic corticosteroid side effects. Consider using an alternative treatment to triamcinolone, such as a corticosteroid not metabolized by CYP3A4 (i.e., beclomethasone or prednisolone). In some patients, a corticosteroid dose adjustment may be needed. If corticosteroid therapy is to be discontinued, consider tapering the dose over a period of time to decrease the potential for withdrawal.
Triazolam: (Contraindicated) Coadministration of triazolam, a primary CYP3A4 substrate, with strong CYP3A4 inhibitors, such as cobicistat, is contraindicated by the manufacturer of triazolam due to the risk for increased and prolonged sedation and respiratory depression. Concurrent use is expected to produce large increases in systemic exposure to triazolam, with the potential for serious adverse effects.
Tricyclic antidepressants: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Trimipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
Trospium: (Minor) Both trospium and tenofovir are eliminated by active renal tubular secretion; coadministration has the potential to increase serum concentrations of trospium or tenofovir due to competition for the drug elimination pathway. Careful patient monitoring and dosage adjustment of trospium and/or tenofovir, PMPA is recommended.
Tucatinib: (Moderate) Coadministration of tenofovir disoproxil fumarate with tucatinib may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-glycoprotein (P-gp) substrate and tucatinib is a P-gp inhibitor. (Moderate) Monitor for cobicistat-related adverse effects if coadministered with tucatinib as concurrent use may increase cobicistat exposure. Cobicistat is a CYP3A4 substrate and tucatinib is a strong CYP3A4 inhibitor.
Ubrogepant: (Contraindicated) Coadministration of ubrogepant and cobicistat is contraindicated as concurrent use may increase ubrogepant exposure and the risk of adverse effects. Ubrogepant is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor resulted in a 9.7-fold increase in the exposure of ubrogepant.
Ulipristal: (Minor) Concomitant use of ulipristal and cobicistat may increase the plasma concentration of ulipristal resulting in an increased risk for ulipristal-related adverse events; however, this is not likely to be significant for single-dose emergency contraceptive use. Ulipristal is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ulipristal overall exposure by 5.9-fold and increased the overall exposure if ulipristal's active metabolite, monodemethyl-ulipristal acetate, by 2.4-fold.
Umeclidinium; Vilanterol: (Moderate) Caution is warranted when cobicistat is administered with umeclidinium; vilanterol as there is a potential for elevated umeclidinium; vilanterol concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Umeclidinium; vilanterol is a substrate of CYP3A4, CYP2D6, and P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp inhibitor.
Upadacitinib: (Major) During concomitant use of upadacitinib and cobicistat reduce the upadacitinib dosage to 15 mg once daily. During induction for ulcerative colitis and Crohn's disease reduce the upadacitinib dosage to 30 mg once daily. Concomitant use may increase upadacitinib exposure and risk for adverse effects. Concomitant use with another strong CYP3A inhibitor increased upadacitinib overall exposure 1.75-fold.
Valacyclovir: (Moderate) Monitor for changes in serum creatinine and phosphorus if tenofovir disoproxil fumarate is administered in combination with nephrotoxic agents, such as valacyclovir. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Concurrent administration with drugs that decrease renal function may increase concentrations of tenofovir. In addition, use with drugs that are also eliminated by active tubular secretion may increase concentrations of the co-administered drug. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir disoproxil fumarate; a majority of the cases occurred in patients who had underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Tenofovir containing products should be avoided with concurrent or recent use of a nephrotoxic agent; patients receiving concomitant nephrotoxic agents should be carefully monitored for changes in serum creatinine and phosphorus, and urine glucose and protein. (Moderate) Monitor for valacyclovir or emtricitabine-related adverse events during concomitant use. Concomitant use may increase valacyclovir or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as valacyclovir and emtricitabine, may increase the risk of adverse reactions.
Valbenazine: (Major) Reduce the dose of valbenazine to 40 mg once daily if coadministration with cobicistat is necessary. Prolongation of the QT interval is not clinically significant at valbenazine concentrations expected with recommended dosing; however, valbenazine concentrations may be higher in patients taking a strong CYP3A4 inhibitor, and QT prolongation may become clinically significant. Valbenazine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased both valbenazine and NBI-98782 exposure by approximately 2-fold.
Valdecoxib: (Moderate) Avoid administering tenofovir, PMPA concurrently with or recently after a nephrotoxic agent, such as high-dose or multiple nonsteroidal antiinflammatory drugs (NSAIDs). Cases of acute renal failure, some requiring hospitalization and renal replacement therapy, have been reported after high-dose or multiple NSAIDs were initiated in patients who appeared stable on tenofovir. Consider alternatives to NSAIDs in patients at risk for renal dysfunction. If these drugs must be coadministered, carefully monitor the estimated creatinine creatinine, serum phosphorus, urine glucose, and urine protein prior to, and periodically during, treatment. (Moderate) Monitor for nonsteroidal antiinflammatory drug (NSAID) or emtricitabine-related adverse events during concomitant use. Concomitant use may increase NSAID or emtricitabine concentrations. Coadministration of drugs that reduce renal function or compete for active tubular secretion, such as NSAIDs and emtricitabine, may increase the risk of adverse reactions.
Valganciclovir: (Moderate) Monitor for changes in serum creatinine and adverse reactions, such as lactic acidosis or hepatotoxicity if emtricitabine is administered in combination with nephrotoxic agents, such as valganciclovir. Consider the potential for drug interaction prior to and during concurrent use of these medications. Both emtricitabine and valganciclovir are excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. While no drug interactions due to competition for renal excretion have been observed, coadministration of these medications may increase concentrations of both drugs. (Minor) Since tenofovir is primarily eliminated by the kidneys, concurrent administration of tenofovir disoproxil with valganciclovir may increase serum concentrations of tenofovir via competition for renal tubular secretion.
Valproic Acid, Divalproex Sodium: (Major) Caution is warranted when cobicistat is administered with valproic acid as there is a potential for altered concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Valproic acid is a weak inhibitor and inducer (in vitro) of CYP3A4; cobicistat is a CYP3A4 substrate.
Valsartan: (Moderate) Caution is warranted when elvitegravir is administered with valsartan as there is a potential for decreased valsartan concentrations. Valsartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Caution is warranted when elvitegravir is administered with valsartan as there is a potential for decreased valsartan concentrations. Valsartan is a substrate of CYP2C9; elvitegravir is a CYP2C9 inducer. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
Vancomycin: (Moderate) Tenofovir should be avoided with concurrent or recent use of a nephrotoxic agent, such as vancomycin. Patients receiving these drugs together should be carefully monitored for changes in serum creatinine and phosphorus. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir; a majority of cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents.
Vardenafil: (Major) Do not use vardenafil orally disintegrating tablets with cobicistat due to increased vardenafil exposure; do not exceed a single dose of 2.5 mg per 72-hour period of vardenafil oral tablets. Vardenafil is primarily metabolized by CYP3A4/5; cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased the AUC of vardenafil by 10 to 16-fold.
Vemurafenib: (Major) Avoid the concomitant use of vemurafenib and cobicistat; vemurafenib exposure may be increased resulting in an increased risk of adverse events, including QT prolongation. If use with cobicistat cannot be avoided, consider a vemurafenib dose reduction; monitor patients closely for the development of adverse events and dose reduce or discontinue therapy based on manufacturer guidance. Vemurafenib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the exposure of vemurafenib by 40%. (Major) Coadministration of with vemurafenib is not recommended as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Vemurafenib is a CYP3A4 inducer, while elvitegravir is a substrate of CYP3A4. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as vemurafenib. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Venetoclax: (Major) Coadministration of cobicistat with venetoclax is contraindicated during the initiation and ramp-up phase in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL); consider an alternative medication or adjust the venetoclax dose with close monitoring for toxicity (e.g., hematologic toxicity, GI toxicity, and tumor lysis syndrome) in patients receiving a steady daily dose of venetoclax if concurrent use is necessary. In patients with acute myeloid leukemia (AML), reduce the venetoclax dose and monitor for toxicity during concurrent use. Resume the original venetoclax dose 2 to 3 days after discontinuation of cobicistat. Specific venetoclax dosage adjustments are as follows: CLL/SLL patients at steady daily dose: 100 mg/day. AML patients: 10 mg on day 1, 20 mg on day 2, 50 mg on day 3, then 100 mg/day starting on day 4. Venetoclax is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a CYP3A4 (strong) and P-gp inhibitor Coadministration of strong CYP3A4 inhibitors increased the venetoclax AUC by 90% to 690% in drug interaction studies, while coadministration with a single dose of another P-gp inhibitor increased venetoclax exposure by 78% in a drug interaction study.
Venlafaxine: (Moderate) Monitor for adverse effects when administering venlafaxine with cobicistat. There is a potential for elevated venlafaxine and cobicistat concentrations if these drugs are given together. Venlafaxine and cobicistat are substrates and inhibitors of CYP2D6. In addition, venlafaxine is a substrate for CYP3A4; cobicistat is a strong inhibitor of CYP3A4.
Verapamil: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as verapamil, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate dose reductions are advised. (Moderate) Coadministration of tenofovir disoproxil fumarate with verapamil may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Tenofovir disoproxil fumarate is a P-gp substrate and verapamil is a P-gp inhibitor.
Vilazodone: (Major) Do not exceed a vilazodone dose of 20 mg once daily if coadministration with cobicistat is necessary; the original dose of vilazodone can be resumed if cobicistat is discontinued. Vilazodone is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased vilazodone exposure by 50%.
Vinblastine: (Moderate) Monitor for an earlier onset and/or increased severity of vinblastine-related adverse reactions, including myelosuppression, constipation, and peripheral neuropathy, if coadministration with cobicistat is necessary. Vinblastine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Vincristine Liposomal: (Major) Avoid coadministration of vincristine with cobicistat due to increased plasma concentrations of vincristine, resulting in an earlier onset and/or increased severity of neuromuscular side effects. Vincristine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Vincristine: (Major) Avoid coadministration of vincristine with cobicistat due to increased plasma concentrations of vincristine, resulting in an earlier onset and/or increased severity of neuromuscular side effects. Vincristine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Vinorelbine: (Moderate) Monitor for an earlier onset and/or increased severity of vinorelbine-related adverse reactions, including constipation and peripheral neuropathy, if coadministration with cobicistat is necessary. Vinorelbine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
Voclosporin: (Contraindicated) Concomitant use of voclosporin and cobicistat is contraindicated; concomitant use may increase the exposure of voclosporin and the risk of voclosporin-related adverse effects such as nephrotoxicity, hypertension, and QT prolongation. Voclosporin is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased voclosporin exposure by approximately 19-fold. (Moderate) Coadministration of tenofovir disoproxil fumarate and voclosporin may result in increased plasma concentrations of tenofovir, leading to an increase in tenofovir-related adverse effects. Concomitant use may also may result in additive nephrotoxicity. Monitor for renal toxicity if concomitant use is required. Tenofovir disoproxil fumarate is a P-gp substrate and voclosporin is a P-gp inhibitor.
Vonoprazan; Amoxicillin; Clarithromycin: (Major) Avoid concurrent use of clarithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of clarithromycin, cobicistat, atazanavir and darunavir. Both clarithromycin and cobicistat are inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir. (Moderate) Caution is advised when administering tenofovir, PMPA, a P-glycoprotein (P-gp) substrate, concurrently with inhibitors of P-gp, such as clarithromycin. Coadministration may result in increased absorption of tenofovir. Monitor for tenofovir-associated adverse reactions.
Vorapaxar: (Major) Avoid coadministration of vorapaxar with cobicistat due to increased plasma concentrations of vorapaxar and the risk of treatment-related adverse reactions. Vorapaxar is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased vorapaxar exposure by 2-fold; the bleeding risk for a change in exposure of this magnitude is not known.
Voriconazole: (Major) Avoid concurrent use of voriconazole with regimens containing cobicistat and atazanavir or darunavir. Use of these drugs together may result in increase plasma concentrations of cobicistat, atazanavir, and darunavir; effects on the voriconazole concentrations has not been determined.
Voxelotor: (Moderate) Monitor for cobicistat-related adverse effects if coadministered with voxelotor as concurrent use may increase cobicistat exposure. Cobicistat is a CYP3A substrate and voxelotor is a moderate CYP3A inhibitor.
Warfarin: (Moderate) Closely monitor the INR if coadministration of warfarin with cobicistat is necessary as concurrent use may increase the exposure of warfarin leading to increased bleeding risk. Cobicistat is a strong CYP3A4 inhibitor and the R-enantiomer of warfarin is a CYP3A4 substrate. The S-enantiomer of warfarin exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer, but the R-enantiomer generally has a slower clearance. (Moderate) Closely monitor the INR if coadministration of warfarin with elvitegravir is necessary as concurrent use may decrease the exposure of warfarin leading to reduced efficacy. Elvitegravir is a weak CYP2C9 inducer and the S-enantiomer, the active metabolite of warfarin, is a CYP2C9 substrate. The S-enantiomer of warfarin exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer, but the R-enantiomer generally has a slower clearance.
Zafirlukast: (Moderate) Caution is warranted when cobicistat is administered with zafirlukast as there is a potential for elevated concentrations of cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Zafirlukast inhibits CYP3A4; cobicistat is a CYP3A4 substrate.
Zaleplon: (Moderate) Zaleplon is partially metabolized by CYP3A4, and concurrent use of strong CYP3A4 inhibitors, such as cobicistat, may decrease the clearance of zaleplon. Coadministration with a moderate CYP3A4 inhibitor increased zaleplon exposure by 20%. Routine dosage adjustments of zaleplon are not required. Dosage adjustments should be made on an individual basis according to efficacy and tolerability.
Zanubrutinib: (Major) Decrease the zanubrutinib dose to 80 mg PO once daily if coadministered with cobicistat. Coadministration may result in increased zanubrutinib exposure and toxicity (e.g., infection, bleeding, and atrial arrhythmias). Interrupt zanubrutinib therapy as recommended for adverse reactions. After discontinuation of cobicistat, resume the previous dose of zanubrutinib. Zanubrutinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. The AUC of zanubrutinib was increased by 278% when coadministered with another strong CYP3A4 inhibitor.
Zavegepant: (Major) Avoid concomitant use of zavegepant and cobicistat. Concomitant use may increase zavegepant exposure and the risk for zavegepant-related adverse effects. Zavegepant is an OATP1B3 substrate and cobicistat is an OATP1B3 inhibitor. Concomitant use with another OATP1B3 inhibitor increased zavegepant overall exposure by 2.3-fold.
Zinc Salts: (Moderate) Separate administration of elvitegravir and zinc by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Zinc: (Moderate) Separate administration of elvitegravir and zinc by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
Ziprasidone: (Moderate) The plasma concentrations of ziprasidone may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as extrapyramidal symptoms and CNS effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while ziprasidone is a CYP3A4 substrate.
Zoledronic Acid: (Moderate) Tenofovir-containing products should be avoided with concurrent or recent use of a nephrotoxic agent, such as zoledronic acid. Tenofovir is primarily excreted via the kidneys by a combination of glomerular filtration and active tubular secretion. Coadministration of tenofovir with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the co-administered drug. Drugs that decrease renal function may also increase concentrations of tenofovir. Renal impairment, which may include hypophosphatemia, has been reported with the use of tenofovir with a majority of the cases occurring in patients who have underlying systemic or renal disease or who are concurrently taking nephrotoxic agents. Monitor patients receiving concomitant nephrotoxic agents for changes in serum creatinine and phosphorus.
Zolmitriptan: (Moderate) Caution is warranted when cobicistat is administered with zolmitriptan as there is a potential for elevated zolmitriptan concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Zolmitriptan is a substrate of CYP3A4; cobicistat is a CYP3A4 inhibitor.
Zolpidem: (Moderate) Consider decreasing the dose of zolpidem if coadministration with cobicistat is necessary. Zolpidem is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with strong CYP3A4 inhibitors increased the AUC of zolpidem by 34% to 70%.
Zonisamide: (Minor) Caution is advised when administering tenofovir disoproxil fumarate concurrently with zonisamide, as coadministration may result in elevated tenofovir plasma concentrations. Inhibitors of the drug transporter P-glycoprotein (P-gp), such as zonisamide, may increase absorption of tenofovir, a P-gp substrate. If these medications are administered together, monitor for tenofovir-associated adverse reactions.

STRIBILD Oral Tab

Adults

1 tablet/day PO (elvitegravir 150 mg/day PO; cobicistat 150 mg/day PO; emtricitabine 200 mg/day PO; tenofovir disoproxil fumarate 300 mg/day PO).

Geriatric

1 tablet/day PO (elvitegravir 150 mg/day PO; cobicistat 150 mg/day PO; emtricitabine 200 mg/day PO; tenofovir disoproxil fumarate 300 mg/day PO).

Adolescents

weighing 35 kg or more: 1 tablet/day PO (elvitegravir 150 mg/day PO; cobicistat 150 mg/day PO; emtricitabine 200 mg/day PO; tenofovir disoproxil fumarate 300 mg/day PO).
weighing less than 35 kg: Safety and efficacy have not been established.

Children

12 years weighing 35 kg or more: 1 tablet/day PO (elvitegravir 150 mg/day PO; cobicistat 150 mg/day PO; emtricitabine 200 mg/day PO; tenofovir disoproxil fumarate 300 mg/day PO).
1 to 11 years or weighing less than 35 kg: Safety and efficacy have not been established.

Infants

Safety and efficacy have not been established.

Neonates

Safety and efficacy have not been established.

Antiviral activity of elvitegravir, emtricitabine, and tenofovir was not antagonistic in cell assays. The addition of cobicistat did not affect antiviral activity.[51664]
 
Elvitegravir: Elvitegravir inhibits the activity of HIV integrase, which is one of three HIV encoded enzymes required for viral replication. Inhibition of integrase by elvitegravir prevents the insertion, or integration, of HIV DNA into the host cell genome, thereby preventing the formation of HIV provirus and propagation of the viral infection. The 50% effective concentration (EC50) ranges from 0.02 to 1.7 nanomolar. Elvitegravir does not inhibit human topoisomerases I or II, nor does it inhibit replication of hepatitis B or C virus.
The major HIV integrase substitutions associated with reduced susceptibility to elvitegravir are T66A/I, E92G/Q, S147G, and Q148R. Cross-resistance occurs among integrase strand transfer inhibitors; however, the degree of cross-resistance depends on the type and number of HIV integrase substitutions.
 
Cobicistat: Cobicistat is an inhibitor of CYP3A enzymes. It is used as a pharmacokinetic enhancer to increase the serum concentration of CYP3A substrates, such as elvitegravir. Cobicistat has no antiviral activity.
 
Emtricitabine: Emtricitabine, a synthetic nucleoside analog of cytidine, is phosphorylated by cellular enzymes to form emtricitabine 5'-triphosphate. Emtricitabine 5'-triphosphate inhibits the activity of HIV-1 reverse transcriptase (RT) by competing with the natural substrate deoxycytidine 5'-triphosphate for incorporation into nascent viral DNA, resulting in chain termination. Emtricitabine 5'-triphosphate is a weak inhibitor of mammalian DNA polymerase alpha, beta, epsilon, and mitochondrial DNA polymerase-gamma.
The antiviral activity of emtricitabine against laboratory and clinical isolates of HIV-1 was assessed in lymphoblastoid cell lines, the MAGI-CCR5 cell line, and peripheral blood mononuclear cells (PBMC). The 50% effective concentration (EC50) values for emtricitabine were in the range of 1.3 to 640 nanomolar. Emtricitabine displayed antiviral activity in cell culture against HIV-1 clades A, B, C, D, E, F, and G (EC50 values ranged from 7 to 75 nanomolar) and showed strain-specific activity against HIV-2 (EC50 values ranged from 7 to 1,500 nanomolar in PBMCs and MAGI cells).
Emtricitabine-resistant isolates of HIV-1 have been selected in cell culture and in vivo. Genotypic analysis of these isolates showed that the reduced susceptibility to emtricitabine was associated with a valine or isoleucine (M184V/I) substitution in the HIV-1 RT. People with the M184V/I mutation are cross-resistant to lamivudine, but retain susceptibility to didanosine, stavudine, tenofovir, and zidovudine, and to non-nucleoside reverse transcriptase inhibitors (NNRTIs). HIV-1 isolates containing the K65R substitution, selected in vivo by abacavir, didanosine, and tenofovir, demonstrated reduced susceptibility to inhibition by emtricitabine. Viruses harboring substitutions conferring reduced susceptibility to zidovudine and stavudine (M41L, D67N, K70R, L210W, T215Y/F, K219Q/E) or didanosine (L74V) remained susceptible to emtricitabine. HIV-1 containing the K103N substitution associated with resistance to NNRTIs was susceptible to emtricitabine.
 
Tenofovir disoproxil fumarate: Tenofovir inhibits viral reverse transcriptase. Tenofovir disoproxil fumarate (tenofovir DF) is an acyclic nucleoside phosphonate (nucleotide) diester analog of adenosine monophosphate. Tenofovir DF requires initial diester hydrolysis for conversion to tenofovir. Tenofovir is then taken up by cells and undergoes phosphorylation to form tenofovir diphosphate (PMPApp). Tenofovir diphosphate competitively inhibits RNA- and DNA-directed reverse transcriptase. Tenofovir diphosphate competes with the natural substrate deoxyadenosine 5'-triphosphate and, since it lacks a 3' hydroxyl group, causes premature DNA termination. The EC50 ranges from 40 to 8,500 nanomolar. Tenofovir diphosphate is a weak inhibitor of mammalian DNA polymerase alpha, beta, and mitochondrial DNA polymerase-gamma.
HIV isolates with reduced susceptibility to tenofovir have been selected in vitro. These viruses expressed the K65R mutation in reverse transcriptase and showed a 2- to 4-fold reduction in susceptibility to tenofovir. Tenofovir resistance due to the K65R and K70E mutations confer cross-resistance with abacavir, didanosine, emtricitabine, and lamivudine.[51664]

Elvitegravir; cobicistat; emtricitabine; tenofovir disoproxil fumarate (DF) tablets are administered orally.[51664]
Elvitegravir: Elvitegravir is 98% to 99% plasma protein bound, and binding is independent of plasma concentration. The mean blood to plasma ratio is 1.37. Elvitegravir is primarily metabolized via CYP3A enzymes and, to a lesser extent, undergoes glucuronidation by UGT1A1/3 enzymes. Elvitegravir is excreted in the feces (94.8%) and urine (6.7%) with a median terminal plasma half-life of approximately 8.7 hours.[58001] [51664]
Cobicistat: Cobicistat is extensively plasma protein bound at 97% to 98%, with a mean blood to plasma ratio of 0.5. The majority of cobicistat metabolism is mediated by CYP3A enzymes with a minor amount of metabolism occurring via CYP2D6 enzymes. Cobicistat is eliminated via the feces (86.2%) and urine (8.2%), with a median terminal plasma half-life of approximately 3.5 hours.[51664]
Emtricitabine: Emtricitabine exhibits low plasma protein binding of less than 4%, and protein binding is independent of plasma concentration. At peak plasma concentration, the mean plasma to blood drug concentration ratio is approximately 1 and the mean semen to plasma drug concentration ratio is approximately 4. Emtricitabine is metabolized via oxidation to 3'-sulfoxide diastereomer (approximately 9% of dose) and via conjugation with glucuronic acid to 2'-O-glucuronide (approximately 4% of dose). Emtricitabine is excreted renally (86%) and via feces (14%). Renal clearance is greater than the estimated creatinine clearance; elimination is presumed to be by both glomerular filtration and active tubular secretion. The plasma half-life of emtricitabine is approximately 10 hours.[30839] [51664]
Tenofovir DF: Plasma protein binding of tenofovir DF is negligible at less than 0.7%. Intracellularly, tenofovir DF undergoes phosphorylation to its active metabolite, tenofovir diphosphate (PMPApp). Neither tenofovir DF nor tenofovir diphosphate are substrates for CYP450 hepatic isoenzymes. Tenofovir is eliminated by a combination of glomerular filtration and active renal tubular secretion, with approximately 70% to 80% of an intravenously administered dose being excreted unchanged in the urine by 72 hours. The terminal elimination half-life of a single oral tenofovir dose is approximately 17 hours.[28193] [51664]
Affected cytochrome P450 isoenzymes and drug transporters: CYP2C9, CYP2D6, CYP3A4, UGT1A 1/3, P-gp, BCRP, MATE1, OATP1B1, and OATP1B3
This monograph discusses a combination product that interacts with multiple hepatic cytochrome P450 (CYP) enzymes and drug transporters. Elvitegravir is a modest inducer of CYP2C9. Elvitegravir also undergoes glucuronidation via the UGT1A1/3 enzymes. The cobicistat component inhibits CYP3A and CYP2D6, and is an inhibitor of the transporters P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), human multidrug and toxic extrusion 1 (MATE1), organic anion transporter polypeptide (OATP1B1), and OATP1B3. Additionally, both elvitegravir and cobicistat are significant substrates of CYP3A, and cobicistat is also metabolized by to a minor extent by CYP2D6. Tenofovir DF is a substrate of P-glycoprotein (P-gp) and BCRP transporters. Concomitant administration with CYP3A4 inducers may lead to a loss of virologic efficacy and possible resistance. Coadministration with a potent CYP3A4 inhibitor (ketoconazole) does not require dosage adjustments.[28193] [51664] [62018]

Oral Route

Administer elvitegravir; cobicistat; emtricitabine; tenofovir DF with food.[51664]
Elvitegravir: Following oral administration, Cmax occurs in 4 hours. Elevations in AUC are observed when administered with food. When compared to fasting conditions, the AUC increases by 34% when administered with a light meal (373 kcal; 20% fat) and 87% when given with a high-fat meal (800 kcal; 50% fat).[51664]
Cobicistat: Peak plasma concentration (Cmax) is observed 3 hours after oral administration. Systemic exposure (AUC) is not significantly affected by the presence of food.[51664]
Emtricitabine: Emtricitabine is rapidly and extensively absorbed, with a mean absolute bioavailability of 93% and a Cmax achieved 3 hours post-dose. The AUC and Cmax increase in proportion to oral dosage over the range of 25 to 200 mg. Administration with food does not significantly alter the AUC of emtricitabine.[30839] [51664]
Tenofovir DF: Oral bioavailability of tenofovir, from tenofovir DF 300 mg, is 25% in the fasted state. Administration with a high-fat meal (700 to 1,000 kcal; 40% to 50% fat) increases bioavailability, with an increase in AUC and Cmax of 40% and 14%, respectively. Light meals (373 kcal; 20% fat) increase mean AUC by 24%. Following administration of a single 300 mg dose in fasting state, the Cmax is achieved in 1.0 +/- 0.4 hours; food delays time to Cmax by approximately 1 hour. The AUC and Cmax are dose proportional over a range of 75 to 600 mg and are not affected by repeated dosing.[28193] [51664]

Pregnancy

Antiretroviral therapy should be provided to all patients during pregnancy, regardless of HIV RNA concentrations or CD4 cell count. Using highly active antiretroviral combination therapy (HAART) to maximally suppress viral replication is the most effective strategy to prevent the development of resistance and to minimize the risk of perinatal transmission. Begin HAART as soon as pregnancy is recognized, or HIV is diagnosed. Elvitegravir; cobicistat; emtricitabine; tenofovir disoproxil fumarate (DF) is not recommended for use as an initial regimen in pregnant patients or those who are trying to conceive, as inadequate concentrations of cobicistat and elvitegravir, as well as viral breakthroughs, have been reported during the second and third trimesters. Consider use of more effective antiretroviral regimens. For people who conceive while suppressed on elvitegravir; cobicistat; emtricitabine; tenofovir DF, guidelines recommend the provider and patient engage in shared decision-making regarding continued use. If the decision is made with the patient to continue use during pregnancy, viral loads should be monitored more frequently (i.e., every 1 to 2 months). Available data from the Antiretroviral Pregnancy Registry (APR), which includes first trimester exposures to elvitegravir (more than 370 exposures), cobicistat (more than 505 exposures), emtricitabine (more than 4,225 exposures), and tenofovir DF (more than 4,655 exposures), have shown no significant difference in the risk of overall major birth defects when compared to the 2.7% background rate among pregnant women in the US. When exposure occurred in the first trimester, the prevalence of defects was 3% (95% CI: 1.5 to 5.2) for elvitegravir, 3.6% (95% CI: 2.11 to 5.5) for cobicistat, 2.7% (95% CI: 2.2 to 3.2) for emtricitabine, and 2.5% (95% CI: 2 to 3) for tenofovir DF. Supplemental data from the APR regarding central nervous system birth defects are available. Among the reported exposures to elvitegravir (343 periconception, 27 late first trimester, 70 second/third trimester), 1 central nervous system birth defect was identified during periconception; however, this was not a neural tube or encephalocele defect. Nucleoside reverse transcriptase inhibitors (NRTIs) are known to induce mitochondrial dysfunction. An association of mitochondrial dysfunction in infants and in utero antiretroviral exposure has been suggested, but not established. While the development of severe or fatal mitochondrial disease in exposed infants appears to be extremely rare, more intensive monitoring of hematologic and electrolyte parameters during the first few weeks of life is advised. Nucleoside analogs have been associated with the development of lactic acidosis, especially during pregnancy. It is unclear if pregnancy augments the incidence of lactic acidosis or hepatic steatosis in patients receiving nucleoside analogs. However, because pregnancy itself can mimic some early symptoms of the lactic acid and hepatic steatosis syndrome or be associated with other significant disorders of liver metabolism, clinicians need to be alert for early diagnosis of this syndrome. Pregnant patients receiving nucleoside analogs should have LFTs and serum electrolytes assessed more frequently during the last trimester of pregnancy and any new symptoms should be evaluated thoroughly. Regular laboratory monitoring is recommended to determine antiretroviral efficacy. Monitor CD4 counts at the initial visit. Patients who have been on HAART for at least 2 years and have consistent viral suppression and CD4 counts consistently greater than 300 cells/mm3 do not need CD4 counts monitored after the initial visit during the pregnancy. However, CD4 counts should be monitored every 3 months during pregnancy for patients on HAART less than 2 years, patients with CD4 count less than 300 cells/mm3, or patients with inconsistent adherence or detectable viral loads. Monitor plasma HIV RNA at the initial visit (with review of prior levels), 2 to 4 weeks after initiating or changing therapy, monthly until undetectable, and then at least every 3 months during pregnancy. Viral load should also be assessed at approximately 36 weeks gestation, or within 4 weeks of delivery, to inform decisions regarding mode of delivery and optimal treatment for newborns. Patients whose HIV RNA levels are above the threshold for resistance testing (usually greater than 500 copies/mL but may be possible for levels greater than 200 copies/mL in some laboratories) should undergo antiretroviral resistance testing (genotypic testing, and if indicated, phenotypic testing). Resistance testing should be conducted before starting therapy in treatment-naive patients who have not been previously tested, starting therapy in treatment-experienced patients (including those who have received pre-exposure prophylaxis), modifying therapy in patients who become pregnant while receiving treatment, or modifying therapy in patients who have suboptimal virologic response to treatment that was started during pregnancy. DO NOT delay initiation of antiretroviral therapy while waiting on the results of resistance testing; treatment regimens can be modified, if necessary, once the testing results are known. First trimester ultrasound is recommended to confirm gestational age and provide accurate estimation of gestational age at delivery. A second trimester ultrasound can be used for both anatomical survey and determination of gestational age in those patients not seen until later in gestation. Perform standard glucose screening in patients receiving antiretroviral therapy at 24 to 28 weeks gestation, although it should be noted that some experts would perform earlier screening with ongoing chronic protease inhibitor-based therapy initiated prior to pregnancy, similar to recommendations for patients with high-risk factors for glucose intolerance. Liver function testing is recommended within 2 to 4 weeks after initiating or changing antiretroviral therapy, and approximately every 3 months thereafter during pregnancy (or as needed). All pregnant patients should be counseled about the importance of adherence to their antiretroviral regimen to reduce the potential for development of resistance and perinatal transmission. It is strongly recommended that antiretroviral therapy, once initiated, not be discontinued. If a patient decides to discontinue therapy, a consultation with an HIV specialist is recommended. There is a pregnancy exposure registry that monitors outcomes in pregnant patients exposed to elvitegravir; cobicistat; emtricitabine; tenofovir disoproxil fumarate; information about the registry can be obtained at www.apregistry.com or by calling 1-800-258-4263.

HIV treatment guidelines recommend clinicians provide mothers with evidence-based, patient-centered counseling to support shared decision-making regarding infant feeding. Inform patients that use of replacement feeding (i.e., formula or banked pasteurized donor human milk) eliminates the risk of HIV transmission; thus, replacement feeding is recommended for use when mothers with HIV are not on antiretroviral therapy (ART) or do not have suppressed viral load during pregnancy, as well as at delivery. For patients on ART who have achieved and maintained viral suppression during pregnancy (at minimum throughout the third trimester) and postpartum, the transmission risk from breast-feeding is less than 1%, but not zero. Virologically suppressed mothers who choose to breast-feed should be supported in this decision. If breast-feeding is chosen, counsel the patient about the importance of adherence to therapy and recommend that the infant be exclusively breast-fed for up to 6 months of age, as exclusive breast-feeding has been associated with a lower rate of HIV transmission as compared to mixed feeding (i.e., breast milk and formula). Promptly identify and treat mastitis, thrush, and cracked or bleeding nipples, as these conditions may increase the risk of HIV transmission through breast-feeding. Breast-fed infants should undergo immediate diagnostic and virologic HIV testing. Testing should continue throughout breast-feeding and up to 6 months after cessation of breast-feeding. For expert consultation, healthcare workers may contact the Perinatal HIV Hotline (888-448-8765). It is unknown if elvitegravir or cobicistat is present in human milk; however, limited data suggest small amounts of emtricitabine and tenofovir are excreted into breast milk. One study estimated the exposure to emtricitabine in exclusively breast-fed infants at approximately 2% of the recommended infant dose. In this same study, tenofovir exposure in exclusively breast-fed infants was found to be equivalent to approximately 4.2 mcg/day. As a result, breast-fed infants whose mothers are receiving treatment may be at risk of developing viral resistance or other associated adverse events. Other antiretroviral medications whose passage into human breast milk has been evaluated include nevirapine, zidovudine, lamivudine, and nelfinavir.