Fortamet

Biguanide Antidiabetics

Oral Administration Oral Solid Formulations

Regular-release tablets:
Administer orally with meals.
 
Extended-release tablets:
Do not crush or chew; have patient swallow whole.
Usually administered once-daily with the evening meal.
The inactive ingredients may occasionally be eliminated in the feces as a soft mass that may resemble the original tablet.

Oral Liquid Formulations

Oral Solution (e.g., Riomet oral solution)
For accurate dosing, use a calibrated spoon, oral syringe, or container to measure the oral solution.
Administer orally with meals.[60715]
 
Oral extended-release Suspension (e.g., Riomet ER suspension)
Shake well for at least 10 seconds prior to each administration.
Measure dosage with the manufacturer provided dosing cup to ensure accurate dosing.
Administer once daily with the evening meal.[64593]
 
Reconstitution method for oral extended-release suspension (prior to dispensing):
Metformin ER suspension is supplied as a powder for oral suspension which must be reconstituted with the accompanying diluent prior to dispensing; both the powder and diluent contain metformin.
Remove the bottles containing drug pellets and drug diluent along with the measuring cup from the box.
Remove the child-resistant cap (push down and turn) from the bottle containing drug pellets and the drug diluent bottle. Keep the child-resistant cap.
Pour the contents of the bottle containing the drug pellets into the diluent bottle and discard the empty pellet bottle.
Close the drug diluent bottle with the child-resistant cap.
Shake continuously in an up and down direction for at least 2 full minutes; this is important for the product to mix evenly.
The concentration of the reconstituted suspension is metformin 500 mg/5mL.
Storage after reconstitution: Store reconstituted suspension in the original bottle at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Do not repackage. Label to discard any unused portion after 100 days.[64593]

Severe

megaloblastic anemia / Delayed / 0-1.0
lactic acidosis / Delayed / 0-0.1
rhabdomyolysis / Delayed / Incidence not known

Moderate

vitamin B12 deficiency / Delayed / 7.0-7.0
hypoglycemia / Early / 1.0-5.0
chest pain (unspecified) / Early / 1.0-5.0
palpitations / Early / 1.0-5.0
metabolic acidosis / Delayed / 0-0.1
folate deficiency / Delayed / Incidence not known
hepatitis / Delayed / Incidence not known
cholestasis / Delayed / Incidence not known
elevated hepatic enzymes / Delayed / Incidence not known

Mild

diarrhea / Early / 9.6-53.2
vomiting / Early / 6.5-25.5
nausea / Early / 6.5-25.5
flatulence / Early / 1.0-12.1
dyspepsia / Early / 1.0-7.1
abdominal pain / Early / 1.0-6.4
headache / Early / 5.7-5.7
dysgeusia / Early / 1.0-5.0
anorexia / Delayed / 1.0-5.0
metallic taste / Early / 1.0-5.0
malaise / Early / 1.0-5.0
myalgia / Early / 1.0-5.0
chills / Rapid / 1.0-5.0
flushing / Rapid / 1.0-5.0
dizziness / Early / 1.0-5.0
rash / Early / 1.0-5.0
hyperhidrosis / Delayed / 1.0-5.0
infection / Delayed / 1.0-5.0
weight loss / Delayed / 10.0

Acidemia, hypoxemia, lactic acidosis, metabolic acidosis

Metformin is contraindicated in patients with metabolic acidosis. Metformin is associated with a risk for lactic acidosis and therefore should not be used in patients with lactic acidosis, a form of metabolic acidosis. Lactic acidosis should be suspected in any diabetic patient with metabolic acidosis lacking evidence of ketoacidosis (ketonuria and ketonemia). Lactic acidosis is a rare but serious complication that can occur due to metformin accumulation; when it occurs, it is fatal in approximately 50% of cases. Lactic acidosis may also occur in association with a number of pathophysiologic conditions, including diabetes mellitus, and whenever there is significant tissue hypoperfusion and hypoxemia or significant renal dysfunction. Certain medications used concomitantly with metformin may also increase the risk of lactic acidosis. Lactic acidosis is characterized by elevated blood lactate levels, acidemia, electrolyte disturbances, an increased anion gap, and an increased lactate/pyruvate ratio. When metformin is implicated as the cause of lactic acidosis, metformin plasma levels more than 5 mcg/mL are generally found. The reported incidence of lactic acidosis in patients receiving metformin is very low; in more than 20,000 patient-years exposure to metformin in clinical trials, there have been no reports of lactic acidosis and approximately 0.03 cases/1,000 patient-years have been estimated with post-marketing surveillance. A nested case-control study of 50,048 patients with type 2 diabetes mellitus demonstrated that during concurrent use of oral diabetes drugs, there were 6 identified cases of lactic acidosis. The crude incidence rate was 3.3 cases per 100,000 person-years in patients treated with metformin; it should be noted that all of the subjects had relevant comorbidities known to be risk factors for lactic acidosis. The onset of lactic acidosis often is subtle, and accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, increasing somnolence, and nonspecific abdominal distress. There may be associated hypothermia, hypotension, and resistant bradycardia with more marked acidemia. The patient and the prescriber must be aware of such symptoms and the patient should be instructed to notify the physician immediately if they occur. Metformin should be withdrawn until the situation is clarified. Serum electrolytes, ketones, blood glucose, and if indicated, blood pH, lactate levels, and even blood metformin levels may be useful.

Fortamet, Glucophage, Glucophage XR, Glumetza, Riomet, RIOMET ER

Rx

Oral biguanide antidiabetic agent
Used for type 2 diabetes mellitus (T2DM) in adult and pediatric patients 10 years and older; first-line T2DM therapy generally includes metformin
Risk of lactic acidosis is low but requires care in prescribing and monitoring

For treatment of type 2 diabetes mellitus as an adjunct to diet and exercise. Oral dosage (immediate-release tablets or solution) Adults

500 mg PO twice daily or 850 mg PO once daily, initially. May increase dose by 500 mg/week or 850 mg every 2 weeks if needed. Doses more than 2,000 mg/day may be better tolerated in 3 divided doses. Max: 2,550 mg/day. Use doses more than 1,000 mg/day with caution in older adults. There is modest additional HbA1c benefit with doses more than 2,000 mg/day; consider tolerance and benefit.

Children and Adolescents 10 to 17 years

500 mg PO twice daily, initially. May increase dose by 500 mg/week if needed. Max: 2,000 mg/day.

Oral dosage (extended-release tablets) Adults

500 mg PO once daily, initially. May increase dose by 500 mg/week if needed. Max: 2,000 mg/day; may consider 1,000 mg PO twice daily if glycemic control is not achieved with 2,000 mg PO once daily. Use doses more than 1,000 mg/day with caution in older adults.

Oral dosage (extended-release suspension) Adults

500 mg PO once daily, initially. May increase dose by 500 mg/week if needed. Max: 2,000 mg/day; may consider 1,000 mg PO twice daily if glycemic control is not achieved with 2,000 mg PO once daily. Use doses more than 1,000 mg/day with caution in older adults.

Children and Adolescents 10 to 17 years

500 mg PO once daily, initially. May increase dose by 500 mg/week if needed. Max: 2,000 mg/day.

For the adjunct treatment of patients with hyperinsulinemia secondary to polycystic ovary syndrome† (PCOS), including the treatment of infertility† in these patients. Oral dosage (regular-release tablets) Adult females

500 mg PO 3 times per day. After roughly 1 month, 33% of females with PCOS will ovulate compared to 4% with placebo. When metformin is added to clomiphene therapy for PCOS with infertility, roughly 86% of patients ovulate in comparison to roughly 8% on clomiphene alone. Worldwide data of metformin use in PCOS to regulate menstrual cycles and decrease ovarian steroidogenesis are relatively extensive. Metformin-failure may occur in severely obese patients, so weight loss and dietary control are also recommended.

For the delay of clinical puberty and early menarche in females with precocious puberty†. Oral dosage Female children older than 6 years

Limited data indicate that 425 mg PO once daily with dinner may be effective. Thirty-eight females with precocious puberty (average age at study initiation 7.9 +/- 0.2 years, average age at diagnosis of precocious puberty 6.8 +/- 0.2 years), low birth weight (less than 2.9 kg for term birth or -1SD for gestational age at preterm birth), and prepuberty (Tanner breast stage 1) were randomized to 425 mg of metformin at bedtime (n = 19) or no therapy (n = 19) in an open-label fashion; patients did not have a history of diabetes mellitus, adrenal hyperplasia, or thyroid abnormalities. After 24 months, patients treated with metformin experienced statistically significant improvements in metabolic abnormalities (i.e., insulin resistance, androgen excess, atherogenic lipid profile, and adipose body composition) as well as a 0.4 year delay in the clinical onset of puberty (defined as Tanner breast stage 2); additionally, metformin treatment was associated with a 1-year delay in the puberty-associated insulin-like growth factor-I rise. Preliminary 3-year data indicate that metformin treatment is associated with a delay in menarche (5/19 patients in the no treatment group have undergone menarche compared to 0/19 patients in the metformin-treated group, p = 0.016). Furthermore, the patients treated with metformin maintained gains in height and lean mass.

For the prolongation of pubertal growth† and to prevent the delay of early menarche in low birth weight females with early-normal onset of puberty. Oral dosage Female children with onset of puberty between 8 and 9 years of age

Limited data indicate that 825 mg PO once daily with dinner may be effective. Twenty-two females with onset of puberty (defined as Tanner breast stage 2) between 8 and 9 years of age (average age at onset 8.6 +/- 0.1 years) and low birth weight (2.8 kg or less for term birth or -1.5 SD for gestational age) were randomized to 850 mg metformin once daily (n = 10) or no treatment (n = 12) in an open-label fashion for 36 months. At enrollment, these patients had a height greater than or equal to 1 SD above midparenteral height for chronological age and bone age of greater than 1 year above chronological age; in addition, all patients had central and progressive puberty. Treatment with metformin resulted in a delay of menarche by a median of 1 year (p < 0.01) and increases in near-adult height (height gain over 42 months of treatment was 16 cm for the untreated group vs. 19.5 cm for the metformin-treated group, p <= 0.05). In addition, patients are still being followed and height has ceased in almost all of the patients in the untreated group, while 4/10 patients in the metformin-treated group continue to grow at a rate of greater than 2 cm/year. In addition, those patients receiving metformin had a leaner body composition and demonstrated lower levels of insulin resistance with improved lipid profiles.

For the treatment of gestational diabetes† or pre-existing type 2 diabetes mellitus during pregnancy† (pregestational diabetes†). Oral dosage (immediate-release) Adults

500 mg PO once nightly for 1 week, then 500 mg PO twice daily. May increase the dose further if needed up to 2.5 to 3 g/day divided in 2 or 3 doses. Metformin is not a first-line agent for gestational diabetes; it has failed to provide adequate glycemic control. Metformine does cross the placenta and long-term safety data for children exposed to metformin in utero are not available. Metformin may be considered during pregnancy in persons with type 2 diabetes mellitus who decline insulin, are unable to safely administer insulin, or otherwise afford insulin.

For the treatment of prediabetes†, including patients with insulin resistance†. Oral dosage (regular-release tablets) Adults

850 mg PO once daily for 1 month, then increase to 850 mg PO twice daily, unless GI adverse effects necessitate a longer titration period.  According to the American Diabetes Association (ADA) Standards of Care, consider metformin for those with prediabetes, especially those 25 to 59 years of age with a BMI of 35 kg/m2 or more, higher fasting plasma glucose (110 mg/dL or greater), higher A1C (6% or greater), and in women with prior gestational diabetes mellitus.

For the treatment of drug-induced obesity† and adverse metabolic effects secondary to antipsychotic medications†. Oral dosage (regular-release tablets) Adults

750 mg to 2 g PO daily in 2 to 3 divided doses has been studied in clinical trials. Doses up to 2.55 g/day have also been used. To minimize GI adverse effects, most trials initiated therapy with 250 mg or 500 mg PO twice daily or 850 mg PO once daily, and increased the dose gradually based on tolerability.[64084] [64085] [64086] [64087] [64088] [64089] [64090] The AACE/ACE guidelines for patients with obesity provide a strong recommendation with strong evidence for the use of metformin in promoting modest weight loss and metabolic improvement in patients who are taking antipsychotic medications.[62881]

Oral dosage (extended-release tablets) Adults

1 g to 2 g PO once daily was the maintenance dose range in clinical trials. To minimize GI adverse effects, trials initiated therapy with 500 mg PO once daily and titrated dosage upwards in 500 mg increments every 2 to 6 weeks based on tolerability.[64091] [64092] The AACE/ACE guidelines for patients with obesity provide a strong recommendation with strong evidence for the use of metformin in promoting modest weight loss and metabolic improvement in patients who are taking antipsychotic medications.[62881]

†Indicates off-label use

Hepatic Impairment

Generally avoid metformin use in hepatic impairment; hepatic disease increases the risk of metformin-associated lactic acidosis.

Renal Impairment

eGFR more than 45 mL/minute/1.73 m2: No dosage adjustment needed per FDA-approved labeling. However, guidelines state to consider a dose reduction to 1,000 mg daily in some patients with eGFR of 45 to 59 mL/minute/1.73 m2 who are at high risk of lactic acidosis.
eGFR 30 to 45 mL/minute/1.73 m2: Initiate at 50% of recommended dose and titrate upwards to a maximum of 1,000 mg/day PO. Initiation of metformin is not recommended per FDA-approved labeling; however, guidelines recommend metformin use in patients with type 2 diabetes, chronic kidney disease, and an eGFR of 30 mL/minute/1.73 m2 or greater. In patients whose eGFR is initially greater than 45 mL/minute/1.73 m2, and then later falls below 45 mL/minute/1.73 m2, assess the benefits and risks of continuing treatment. Discontinue metformin if the eGFR later falls below 30 mL/minute/1.73 m2.
eGFR less than 30 mL/minute/1.73 m2: Use is contraindicated.
 
Intermittent hemodialysis
Metformin use is contraindicated. Metformin is dialyzable; hemodialysis will efficiently remove accumulated metformin in the case of drug-induced lactic acidosis, provided metformin is halted.

Abacavir; Dolutegravir; Lamivudine: (Major) If these drugs are used in combination, the total daily dose of metformin must not exceed 1,000 mg/day. Dolutegravir may increase exposure to metformin. Increased exposure to metformin may increase the risk for hypoglycemia, gastrointestinal side effects, and potentially increase the risk for lactic acidosis. Consider the benefits and risks of concomitant use of dolutegravir with metformin. Close monitoring of blood glucose and patient clinical status (gastrointestinal side effects, renal function, electrolytes and acid-base balance) is recommended. When stopping dolutegravir, the metformin dose may need to be adjusted. In drug interaction studies, dolutegravir increased both the Cmax and AUC of metformin when metformin 500 mg PO twice daily was coadministered. Dolutegravir inhibits common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2]/multidrug and toxin extrusion [MATE1 and MATE2k]). (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Abacavir; Lamivudine, 3TC: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Abacavir; Lamivudine, 3TC; Zidovudine, ZDV: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Acalabrutinib: (Moderate) Consider the benefits and risks of concomitant therapy of acalabrutinib with metformin. Concomitant use o fmedications that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., MATE inhibitors) could increase systemic exposure to metformin and increase the risk for lactic acidosis. The active metabolite of acalabrutinib (ACP-5862) inhibits MATE1 in vitro and may have the potential to increase concentrations of coadministered substrates of these transporters.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Guaifenesin; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetaminophen; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Acetazolamide: (Moderate) Carbonic anhydrase inhibitors such as acetazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of acetazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Acrivastine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Adefovir: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion (e.g., adefovir) may decrease metformin elimination by competing for common renal tubular transport systems. Although such interactions remain theoretical, careful patient monitoring and dose adjustment of metformin and/or the interfering cationic drug are recommended.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Amlodipine; Benazepril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Amlodipine; Olmesartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Amlodipine; Valsartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Amoxicillin; Clarithromycin; Omeprazole: (Moderate) The concomitant use of clarithromycin and antidiabetic agents can result in significant hypoglycemia. Careful monitoring of blood glucose is recommended.
Amphetamine: (Moderate) Monitor for loss of glycemic control when amphetamines are administered to patients taking antidiabetic agents. Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Sympathomimetic agents, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells.
Amphetamine; Dextroamphetamine: (Moderate) Monitor for loss of glycemic control when amphetamines are administered to patients taking antidiabetic agents. Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Sympathomimetic agents, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells.
Amphetamines: (Moderate) Monitor for loss of glycemic control when amphetamines are administered to patients taking antidiabetic agents. Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Sympathomimetic agents, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells.
Androgens: (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Angiotensin II receptor antagonists: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Angiotensin-converting enzyme inhibitors: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Atazanavir; Cobicistat: (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.
Atenolol; Chlorthalidone: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
atypical antipsychotic: (Moderate) Monitor blood glucose during concomitant atypical antipsychotic and metformin use. Atypical antipsychotic therapy may aggravate diabetes mellitus. Atypical antipsychotics have been associated with metabolic changes, including hyperglycemia, diabetic ketoacidosis, hyperosmolar, hyperglycemic states, and diabetic coma. Possible mechanisms include atypical antipsychotic-induced insulin resistance or direct beta-cell inhibition.
Azilsartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Azilsartan; Chlorthalidone: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Benazepril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Benzphetamine: (Moderate) Monitor for loss of glycemic control when amphetamines are administered to patients taking antidiabetic agents. Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Sympathomimetic agents, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells.
Beta-blockers: (Moderate) Increased frequency of blood glucose monitoring may be required when a beta blocker is given with antidiabetic agents. Since beta blockers inhibit the release of catecholamines, these medications may hide symptoms of hypoglycemia such as tremor, tachycardia, and blood pressure changes. Other symptoms, like headache, dizziness, nervousness, mood changes, or hunger are not blunted. Beta-blockers also exert complex actions on the body's ability to regulate blood glucose. Some beta-blockers, particularly non-selective beta-blockers such as propranolol, have been noted to potentiate insulin-induced hypoglycemia and a delay in recovery of blood glucose to normal levels. Hyperglycemia has been reported as well and is possibly due to beta-2 receptor blockade in the beta cells of the pancreas. A selective beta-blocker may be preferred in patients with diabetes mellitus, if appropriate for the patient's condition. Selective beta-blockers, such as atenolol or metoprolol, do not appear to potentiate insulin-induced hypoglycemia. While beta-blockers may have negative effects on glycemic control, they reduce the risk of cardiovascular disease and stroke in patients with diabetes and their use should not be avoided in patients with compelling indications for beta-blocker therapy when no other contraindications are present.
Bictegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) Caution is advised when administering bictegravir with metformin, as coadministration may increase exposure to metformin and increase the risk for hypoglycemia, gastrointestinal side effects, and potentially increase the risk for lactic acidosis. Close monitoring of blood glucose and patient clinical status is recommended. In drug interaction studies, bictegravir increased both the Cmax and AUC of metformin at a metformin dose of 500 mg PO twice daily. Bictegravir inhibits common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2]/multidrug and toxin extrusion [MATE1]).
Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Bortezomib: (Moderate) During clinical trials of bortezomib, hypoglycemia and hyperglycemia were reported in diabetic patients receiving antidiabetic agents. Patients taking antidiabetic agents and receiving bortezomib treatment may require close monitoring of their blood glucose levels and dosage adjustment of their medication.
Brigatinib: (Moderate) Consider the benefits and risks of concomitant therapy of brigatinib with metformin. Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., MATE inhibitors) could increase systemic exposure to metformin and increase the risk for lactic acidosis. Brigatinib inhibits MATE1 and MATE2K in vitro and may have the potential to increase concentrations of coadministered substrates of these transporters.
Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Brompheniramine; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Brompheniramine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Coadministration of glycopyrrolate with metformin my increase metformin plasma concentrations, which may lead to increased metformin effects and possible adverse events. If coadministration is necessary, monitor clinical response to metformin and adjust metformin dose accordingly.
Bumetanide: (Minor) Bumetanide has been associated with hyperglycemia, possibly due to potassium depletion, and, glycosuria has been reported. Because of this, a potential pharmacodynamic interaction exists between bumetanide and all antidiabetic agents. This interference can lead to a loss of diabetic control, so diabetic patients should be monitored closely.
Calcium Carbonate; Famotidine; Magnesium Hydroxide: (Minor) Famotidine may decrease the renal clearance of metformin secondary to competition for renal tubular transport systems. Such an interaction has been observed when cimetidine was administered with metformin. The decrease in renal excretion led to a 40% increase in metformin AUC. Although interactions with cationic drugs remain theoretical (except for cimetidine), caution is warranted when famotidine and metformin are prescribed concurrently. Famotidine may be less likely to interact with metformin versus cimetidine or ranitidine because of less tubular excretion.
Candesartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Capmatinib: (Moderate) Monitor for an increased risk of metformin-related adverse reactions including lactic acidosis if coadministration with capmatinib is necessary; consider the benefits and risks of concomitant use. Metformin is a substrate of multidrug and toxin extrusion (MATE) and capmatinib is a MATE1 and MATE2K inhibitor. Coadministration may interfere with the renal elimination of metformin and increase metformin exposure.
Captopril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Cephalexin: (Moderate) Monitor for metformin-related adverse reactions during concomitant cephalexin use; a metformin dosage adjustment may be necessary. Concomitant use results in increased serum metformin concentrations and decreased renal clearance of metformin. In healthy subjects given single cephalexin 500 mg doses and metformin, serum metformin mean Cmax and AUC increased by an average of 34% and 24%, respectively, and metformin mean renal clearance decreased by 14%.
Cetirizine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chloroquine: (Major) Careful monitoring of blood glucose is recommended when chloroquine and antidiabetic agents, including metformin, are coadministered. A decreased dose of the antidiabetic agent may be necessary as severe hypoglycemia has been reported in patients treated concomitantly with chloroquine and an antidiabetic agent.
Chlorothiazide: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chlorpheniramine; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chlorpheniramine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Chlorpropamide: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Chlorthalidone: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Chlorthalidone; Clonidine: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Minor) Increased frequency of blood glucose monitoring may be required when clonidine is given with antidiabetic agents. Since clonidine inhibits the release of catecholamines, clonidine may hide symptoms of hypoglycemia such as tremor, tachycardia, and blood pressure changes. Other symptoms, like headache, dizziness, nervousness, mood changes, or hunger are not blunted. Clonidine does not appear to impair recovery from hypoglycemia, and has not been found to impair glucose tolerance in diabetic patients.
Chromium: (Moderate) Chromium dietary supplements may lower blood glucose. As part of the glucose tolerance factor molecule, chromium appears to facilitate the binding of insulin to insulin receptors in tissues and to aid in glucose metabolism. Because blood glucose may be lowered by the use of chromium, patients who are on antidiabetic agents may need dose adjustments. Close monitoring of blood glucose is recommended.
Cimetidine: (Moderate) Concomitant administration of metformin and cimetidine may increase metformin exposure and increase the risk for lactic acidosis. If these drugs are given together, monitor for signs of metformin toxicity; metformin dose adjustments may be needed. After administration of single doses of cimetidine 400 mg and metformin 850 mg, mean metformin exposure increased by 40%. Metformin is an OCT2 substrate; cimetidine is an OCT2 inhibitor that may decrease metformin elimination by blocking renal tubular secretion.
Cisapride: (Moderate) Because cisapride can enhance gastric emptying in diabetic patients, blood glucose can be affected, which, in turn, may affect the clinical response to antidiabetic agents. Monitor blood glucose and adjust if cliniically indicated.
Clarithromycin: (Moderate) The concomitant use of clarithromycin and antidiabetic agents can result in significant hypoglycemia. Careful monitoring of blood glucose is recommended.
Clofarabine: (Moderate) Concomitant use of clofarabine and metformin may result in altered clofarabine levels because both agents are a substrate of OCT1. Therefore, monitor for signs of clofarabine toxicity such as gastrointestinal toxicity (e.g., nausea, vomiting, diarrhea, mucosal inflammation), hematologic toxicity, and skin toxicity (e.g., hand and foot syndrome, rash, pruritus) in patients also receiving OCT1 substrates.
Clonidine: (Minor) Increased frequency of blood glucose monitoring may be required when clonidine is given with antidiabetic agents. Since clonidine inhibits the release of catecholamines, clonidine may hide symptoms of hypoglycemia such as tremor, tachycardia, and blood pressure changes. Other symptoms, like headache, dizziness, nervousness, mood changes, or hunger are not blunted. Clonidine does not appear to impair recovery from hypoglycemia, and has not been found to impair glucose tolerance in diabetic patients.
Cobicistat: (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.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Codeine; Phenylephrine; Promethazine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Colesevelam: (Moderate) The clinical response to metformin extended-release (metformin ER) should be monitored in patients receiving concomitant therapy with colesevelam. Be alert for changes in glycemic control, increased metformin side effects, such as gastrointestinal disturbances and a risk for lactic acidosis. Colesevelam increases the Cmax and AUC of metformin ER by approximately 8% and 44%, respectively. The mechanism of the interaction is not known. Colesevelam has no significant effect on the bioavailability of immediate-release metformin.
Conjugated Estrogens: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Conjugated Estrogens; Bazedoxifene: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Conjugated Estrogens; Medroxyprogesterone: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Corticosteroids: (Moderate) Monitor blood glucose during concomitant corticosteroid and metformin use; a metformin dose adjustment may be necessary. Corticosteroids may increase blood glucose concentrations. Risk factors for impaired glucose tolerance due to corticosteroids include the corticosteroid dose and duration of treatment. Corticosteroids stimulate hepatic glucose production and inhibit peripheral glucose uptake into muscle and fatty tissues, producing insulin resistance. Decreased insulin production may occur in the pancreas due to a direct effect on pancreatic beta cells.
Cyanocobalamin, Vitamin B12: (Minor) Metformin may result in suboptimal oral vitamin B12 absorption by competitively blocking the calcium-dependent binding of the intrinsic factor-vitamin B12 complex to its receptor. Regular measurement of hematologic parameters is recommended in all patients on chronic metformin treatment; abnormalities should be investigated.
Cyclosporine: (Moderate) Patients should be monitored for worsening glycemic control if therapy with cyclosporine is initiated in patients receiving antidiabetic agents. Cyclosporine has been reported to cause hyperglycemia or exacerbate diabetes mellitus; this effect appears to be dose-related and caused by direct beta-cell toxicity. Also, any drug that deteriorates the renal status of the patient is likely to alter metformin concentrations in the body, so renal function should be carefully monitored during the use of cyclosporine and metformin together.
Daclatasvir: (Moderate) Closely monitor blood glucose levels if daclatasvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as daclatasvir.
Danazol: (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Darunavir; Cobicistat: (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.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (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.
Desloratadine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Desogestrel; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Dexbrompheniramine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Dextroamphetamine: (Moderate) Monitor for loss of glycemic control when amphetamines are administered to patients taking antidiabetic agents. Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Sympathomimetic agents, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Diazoxide: (Minor) Diazoxide, when administered intravenously or orally, produces a prompt dose-related increase in blood glucose level, due primarily to an inhibition of insulin release from the pancreas, and also to an extrapancreatic effect. The hyperglycemic effect begins within an hour and generally lasts no more than 8 hours in the presence of normal renal function. The hyperglycemic effect of diazoxide is expected to be antagonized by certain antidiabetic agents (e.g., insulin or a sulfonylurea). Blood glucose should be closely monitored.
Dichlorphenamide: (Moderate) Carbonic anhydrase inhibitors such as dichlorphenamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of dichlorphenamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Dienogest; Estradiol valerate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Diethylstilbestrol, DES: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Digoxin: (Moderate) Metformin may increase digoxin concentrations, but the magnitude is unclear. Measure serum digoxin concentrations before initiating metformin, and periodically after that. Monitor heart rate and other clinical parameters. Adjust digoxin dose as necessary.
Diphenhydramine; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Disopyramide: (Moderate) Disopyramide may enhance the hypoglycemic effects of antidiabetic agents. Patients receiving disopyramide concomitantly with antidiabetic agents should be monitored for changes in glycemic control.
Dofetilide: (Major) Dofetilide should be co-administered with metformin 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. Reduced clearance of metformin may increase the risk for lactic acidosis; increased concentrations of dofetilide may increase the risk for side effects including proarrhythmia. Careful patient monitoring and dose adjustment of metformin and dofetilide is recommended.
Dolutegravir: (Major) If these drugs are used in combination, the total daily dose of metformin must not exceed 1,000 mg/day. Dolutegravir may increase exposure to metformin. Increased exposure to metformin may increase the risk for hypoglycemia, gastrointestinal side effects, and potentially increase the risk for lactic acidosis. Consider the benefits and risks of concomitant use of dolutegravir with metformin. Close monitoring of blood glucose and patient clinical status (gastrointestinal side effects, renal function, electrolytes and acid-base balance) is recommended. When stopping dolutegravir, the metformin dose may need to be adjusted. In drug interaction studies, dolutegravir increased both the Cmax and AUC of metformin when metformin 500 mg PO twice daily was coadministered. Dolutegravir inhibits common renal tubular transp

ort systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2]/multidrug and toxin extrusion [MATE1 and MATE2k]).
Dolutegravir; Lamivudine: (Major) If these drugs are used in combination, the total daily dose of metformin must not exceed 1,000 mg/day. Dolutegravir may increase exposure to metformin. Increased exposure to metformin may increase the risk for hypoglycemia, gastrointestinal side effects, and potentially increase the risk for lactic acidosis. Consider the benefits and risks of concomitant use of dolutegravir with metformin. Close monitoring of blood glucose and patient clinical status (gastrointestinal side effects, renal function, electrolytes and acid-base balance) is recommended. When stopping dolutegravir, the metformin dose may need to be adjusted. In drug interaction studies, dolutegravir increased both the Cmax and AUC of metformin when metformin 500 mg PO twice daily was coadministered. Dolutegravir inhibits common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2]/multidrug and toxin extrusion [MATE1 and MATE2k]). (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Dolutegravir; Rilpivirine: (Major) If these drugs are used in combination, the total daily dose of metformin must not exceed 1,000 mg/day. Dolutegravir may increase exposure to metformin. Increased exposure to metformin may increase the risk for hypoglycemia, gastrointestinal side effects, and potentially increase the risk for lactic acidosis. Consider the benefits and risks of concomitant use of dolutegravir with metformin. Close monitoring of blood glucose and patient clinical status (gastrointestinal side effects, renal function, electrolytes and acid-base balance) is recommended. When stopping dolutegravir, the metformin dose may need to be adjusted. In drug interaction studies, dolutegravir increased both the Cmax and AUC of metformin when metformin 500 mg PO twice daily was coadministered. Dolutegravir inhibits common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2]/multidrug and toxin extrusion [MATE1 and MATE2k]).
Donepezil; Memantine: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Drugs that are eliminated by renal tubular secretion (e.g., memantine) may decrease metformin elimination by competing for common renal tubular transport systems. It should be noted that in a pharmacokinetic study in which memantine and glyburide; metformin (Glucovance) were coadministered, the pharmacokinetics of memantine, metformin, or glyburide were not altered. Regardless, careful patient monitoring is recommended.
Doravirine; Lamivudine; Tenofovir disoproxil fumarate: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Drospirenone: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Drospirenone; Estetrol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Drospirenone; Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Drospirenone; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Minor) Levomefolate and metformin should be used together cautiously. Plasma concentrations of levomefolate may be reduced during treatment of type 2 diabetes with metformin. Monitor patients for decreased efficacy of levomefolate if these agents are used together. (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Elagolix; Estradiol; Norethindrone acetate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Elbasvir; Grazoprevir: (Moderate) Closely monitor blood glucose levels if elbasvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as elbasvir.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (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.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (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.
Enalapril, Enalaprilat: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Entecavir: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion (e.g., entecavir) may decrease metformin elimination by competing for common renal tubular transport systems. Although such interactions remain theoretical, careful patient monitoring and dose adjustment of metformin and/or the interfering cationic drug are recommended.
Ephedrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Ephedrine; Guaifenesin: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Eprosartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Erdafitinib: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Esterified Estrogens: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Esterified Estrogens; Methyltestosterone: (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together. (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Estradiol; Levonorgestrel: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Estradiol; Norethindrone: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Estradiol; Norgestimate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Estradiol; Progesterone: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Estramustine: (Minor) Estramustine should be used cautiously in patients receiving metformin. Patients should routinely monitor their blood glucose as indicated. Estramustine may decrease glucose tolerance leading to hyperglycemia.
Estrogens: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Estropipate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis.
Ethacrynic Acid: (Moderate) Loop diuretics can decrease the hypoglycemic effects of antidiabetic agents by producing an increase in blood glucose concentrations. Patients receiving antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
Ethanol: (Major) Patients taking metformin should be advised to avoid alcohol use. Blood lactate concentrations and the lactate to pyruvate ratio are increased during excessive (acute or chronic) intake of alcohol with metformin.
Ethinyl Estradiol; Norelgestromin: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Ethinyl Estradiol; Norethindrone Acetate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Ethinyl Estradiol; Norgestrel: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Ethotoin: (Minor) Ethotoin and other hydantoins have the potential to increase blood glucose and thus interact with antidiabetic agents pharmacodynamically. Monitor blood glucose for changes in glycemic control. Dosage adjustments may be necessary in some patients.
Ethynodiol Diacetate; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Etonogestrel: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Etonogestrel; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Famotidine: (Minor) Famotidine may decrease the renal clearance of metformin secondary to competition for renal tubular transport systems. Such an interaction has been observed when cimetidine was administered with metformin. The decrease in renal excretion led to a 40% increase in metformin AUC. Although interactions with cationic drugs remain theoretical (except for cimetidine), caution is warranted when famotidine and metformin are prescribed concurrently. Famotidine may be less likely to interact with metformin versus cimetidine or ranitidine because of less tubular excretion.
Fedratinib: (Moderate) Concurrent use of metformin and fedratinib may produce unpredictable effects. Concomitant administration may increase the risk for metformin adverse events (e.g., lactic acidosis) or reduce metformin's efficacy. If these drugs are given together, monitor for metformin toxicity and efficacy; metformin dose adjustments may be needed. Fedratinib inhibits the common renal tubular transport systems involved in the renal elimination of metformin (e.g., OCT2/MATE1 and MATE2). In a drug interaction study, fedratinib was observed to have no clinically meaningful effect on metformin overall exposure; however, the renal clearance of metformin was decreased by 36% and the glucose lowering effect of metformin appeared to be reduced. The baseline adjusted glucose exposure was about 50% higher in response to an oral glucose challenge when these drugs were administered together.
Fenofibrate: (Moderate) Monitor blood glucose during concomitant metformin and fibric acid derivative use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Fenofibric Acid: (Moderate) Monitor blood glucose during concomitant metformin and fibric acid derivative use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Fexofenadine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Fibric acid derivatives: (Moderate) Monitor blood glucose during concomitant metformin and fibric acid derivative use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Fluoxetine: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Fosinopril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Fosphenytoin: (Minor) Fosphenytoin and other hydantoins have the potential to increase blood glucose and thus interact with antidiabetic agents pharmacodynamically. Monitor blood glucose for changes in glycemic control. Dosage adjustments may be necessary in some patients.
Furosemide: (Minor) Furosemide may cause hyperglycemia and glycosuria in patients with diabetes mellitus, probably due to diuretic-induced hypokalemia.
Garlic, Allium sativum: (Moderate) Patients receiving antidiabetic agents should use dietary supplements of Garlic, Allium sativum with caution. Constituents in garlic might have some antidiabetic activity, and may increase serum insulin levels and increase glycogen storage in the liver. Monitor blood glucose and glycemic control. Patients with diabetes should inform their health care professionals of their intent to ingest garlic dietary supplements. Some patients may require adjustment to their hypoglycemic medications over time. One study stated that additional garlic supplementation (0.05 to 1.5 grams PO per day) contributed to improved blood glucose control in patients with type 2 diabetes mellitus within 1 to 2 weeks, and had positive effects on total cholesterol and high/low density lipoprotein regulation over time. It is unclear if hemoglobin A1C is improved or if improvements are sustained with continued treatment beyond 24 weeks. Other reviews suggest that garlic may provide modest improvements in blood lipids, but few studies demonstrate decreases in blood glucose in diabetic and non-diabetic patients. More controlled trials are needed to discern if garlic has an effect on blood glucose in patients with diabetes. When garlic is used in foods or as a seasoning, or at doses of 50 mg/day or less, it is unlikely that blood glucose levels are affected to any clinically significant degree.
Gemfibrozil: (Moderate) Monitor blood glucose during concomitant metformin and fibric acid derivative use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Glecaprevir; Pibrentasvir: (Moderate) Closely monitor blood glucose levels if glecaprevir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as glecaprevir. (Moderate) Closely monitor blood glucose levels if pibrentasvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as pibrentasvir.
Glimepiride: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Glipizide: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Glipizide; Metformin: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Glyburide: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Glyburide; Metformin: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Glycopyrrolate: (Moderate) Coadministration of glycopyrrolate with metformin my increase metformin plasma concentrations, which may lead to increased metformin effects and possible adverse events. If coadministration is necessary, monitor clinical response to metformin and adjust metformin dose accordingly.
Glycopyrrolate; Formoterol: (Moderate) Coadministration of glycopyrrolate with metformin my increase metformin plasma concentrations, which may lead to increased metformin effects and possible adverse events. If coadministration is necessary, monitor clinical response to metformin and adjust metformin dose accordingly.
Green Tea: (Moderate) Green tea catechins have been shown to decrease serum glucose concentrations in vitro. Patients with diabetes mellitus taking antidiabetic agents should be monitored closely for hypoglycemia if consuming green tea products.
Guaifenesin; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Guaifenesin; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Hydrocodone; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Hydroxychloroquine: (Moderate) Monitor blood glucose during concomitant metformin and hydroxychloroquine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Hydroxyprogesterone: (Minor) Progestins, like hydroxyprogesterone, can impair glucose tolerance. Patients receiving antidiabetic agents should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued.
Ibuprofen; Famotidine: (Minor) Famotidine may decrease the renal clearance of metformin secondary to competition for renal tubular transport systems. Such an interaction has been observed when cimetidine was administered with metformin. The decrease in renal excretion led to a 40% increase in metformin AUC. Although interactions with cationic drugs remain theoretical (except for cimetidine), caution is warranted when famotidine and metformin are prescribed concurrently. Famotidine may be less likely to interact with metformin versus cimetidine or ranitidine because of less tubular excretion.
Ibuprofen; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Indacaterol; Glycopyrrolate: (Moderate) Coadministration of glycopyrrolate with metformin my increase metformin plasma concentrations, which may lead to increased metformin effects and possible adverse events. If coadministration is necessary, monitor clinical response to metformin and adjust metformin dose accordingly.
Indapamide: (Moderate) A potential pharmacodynamic interaction exists between indapamide and antidiabetic agents, like metformin. Indapamide can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia.
Insulin Aspart: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Aspart; Insulin Aspart Protamine: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Degludec: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Degludec; Liraglutide: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Detemir: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Glargine: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Glargine; Lixisenatide: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Glulisine: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Lispro: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin Lispro; Insulin Lispro Protamine: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulin, Inhaled: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Insulins: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Iodipamide Meglumine: (Contraindicated) Metformin and combination products containing metformin should be temporarily discontinued prior to the administration of iodinated contrast media. Metformin should be held for at least 48 hours after contrast administration and not restarted until renal function returns to normal post-procedure. Lactic acidosis has been reported in patients taking metformin that experience nephrotoxicity after use of iodinated contrast media.
Ionic Contrast Media: (Contraindicated) Metformin and combination products containing metformin should be temporarily discontinued prior to the administration of iodinated contrast media. Metformin should be held for at least 48 hours after contrast administration and not restarted until renal function returns to normal post-procedure. Lactic acidosis has been reported in patients taking metformin that experience nephrotoxicity after use of iodinated contrast media.
Ioxaglate Meglumine; Ioxaglate Sodium: (Contraindicated) Metformin and combination products containing metformin should be temporarily discontinued prior to the administration of iodinated contrast media. Metformin should be held for at least 48 hours after contrast administration and not restarted until renal function returns to normal post-procedure. Lactic acidosis has been reported in patients taking metformin that experience nephrotoxicity after use of iodinated contrast media.
Irbesartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Isophane Insulin (NPH): (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Ketoconazole: (Moderate) Concomitant administration of metformin and ketoconazole may increase metformin exposure and increase the risk for lactic acidosis. If these drugs are given together, monitor for signs of metformin toxicity; metformin dose adjustments may be needed. Metformin is a human multidrug and toxic extrusion (MATE) and OCT2 substrate and ketoconazole is a MATE and OCT2 inhibitor. MATE and OCT2 inhibitors may decrease metformin elimination by blocking renal tubular secretion.
Lamivudine, 3TC: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Lamivudine, 3TC; Zidovudine, ZDV: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Lamivudine; Tenofovir Disoproxil Fumarate: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, such as lamivudine, may decrease metformin elimination by competing for common renal tubular transport systems.
Lamotrigine: (Moderate) Concomitant administration of metformin and lamotrigine may increase metformin exposure and increase the risk for lactic acidosis. If these drugs are given together, monitor for signs of metformin toxicity; metformin dose adjustments may be needed. Metformin is an OCT2 substrate; lamotrigine is an OCT2 inhibitor that may decrease metformin elimination by blocking renal tubular secretion.
Lanreotide: (Moderate) Monitor blood glucose levels regularly in patients with diabetes, especially when lanreotide treatment is initiated or when the dose is altered. Adjust treatment with antidiabetic agents as clinically indicated. Lanreotide inhibits the secretion of insulin and glucagon. Patients treated with lanreotide may experience either hypoglycemia or hyperglycemia.
Lansoprazole; Amoxicillin; Clarithromycin: (Moderate) The concomitant use of clarithromycin and antidiabetic agents can result in significant hypoglycemia. Careful monitoring of blood glucose is recommended.
Ledipasvir; Sofosbuvir: (Moderate) Closely monitor blood glucose levels if ledipasvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agent(s) may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as ledipasvir. (Moderate) Closely monitor blood glucose levels if sofosbuvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as sofosbuvir.
Leuprolide; Norethindrone: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Levoketoconazole: (Moderate) Concomitant administration of metformin and ketoconazole may increase metformin exposure and increase the risk for lactic acidosis. If these drugs are given together, monitor for signs of metformin toxicity; metformin dose adjustments may be needed. Metformin is a human multidrug and toxic extrusion (MATE) and OCT2 substrate and ketoconazole is a MATE and OCT2 inhibitor. MATE and OCT2 inhibitors may decrease metformin elimination by blocking renal tubular secretion.
Levomefolate: (Minor) Levomefolate and metformin should be used together cautiously. Plasma concentrations of levomefolate may be reduced during treatment of type 2 diabetes with metformin. Monitor patients for decreased efficacy of levomefolate if these agents are used together.
Levonorgestrel: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Levonorgestrel; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Levothyroxine: (Minor) Thyroid hormone use may result in increased blood sugar and a loss of glycemic control in some patients. Interactions may or may not be clinically significant at usual replacement doses. Monitor blood sugars carefully when thyroid therapy is added, changed, or discontinued in patients receiving metformin.
Levothyroxine; Liothyronine (Porcine): (Minor) Thyroid hormone use may result in increased blood sugar and a loss of glycemic control in some patients. Interactions may or may not be clinically significant at usual replacement doses. Monitor blood sugars carefully when thyroid therapy is added, changed, or discontinued in patients receiving metformin.
Levothyroxine; Liothyronine (Synthetic): (Minor) Thyroid hormone use may result in increased blood sugar and a loss of glycemic control in some patients. Interactions may or may not be clinically significant at usual replacement doses. Monitor blood sugars carefully when thyroid therapy is added, changed, or discontinued in patients receiving metformin.
Linezolid: (Moderate) Hypoglycemia, including symptomatic episodes, has been noted in post-marketing reports with linezolid in patients with diabetes mellitus receiving therapy with antidiabetic agents, such as insulin and oral hypoglycemic agents. Diabetic patients should be monitored for potential hypoglycemic reactions while on linezolid. If hypoglycemia occurs, discontinue or decrease the dose of the antidiabetic agent or discontinue the linezolid therapy. Linezolid is a reversible, nonselective MAO inhibitor and other MAO inhibitors have been associated with hypoglycemic episodes in diabetic patients receiving insulin or oral hypoglycemic agents.
Liothyronine: (Minor) Thyroid hormone use may result in increased blood sugar and a loss of glycemic control in some patients. Interactions may or may not be clinically significant at usual replacement doses. Monitor blood sugars carefully when thyroid therapy is added, changed, or discontinued in patients receiving metformin.
Lisdexamfetamine: (Moderate) Monitor for loss of glycemic control when amphetamines are administered to patients taking antidiabetic agents. Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Sympathomimetic agents, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells.
Lisinopril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Lonapegsomatropin: (Moderate) Patients with diabetes mellitus should be monitored closely during somatropin (recombinant rhGH) therapy. Antidiabetic drugs (e.g., insulin or oral agents) may require adjustment when somatropin therapy is instituted in these patients. Growth hormones, such as somatropin, may decrease insulin sensitivity, leading to glucose intolerance and loss of blood glucose control. Therefore, glucose levels should be monitored periodically in all patients treated with somatropin, especially in those with risk factors for diabetes mellitus.
Loratadine; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Lorcaserin: rong> (Moderate) In general, weight reduction may increase the risk of hypoglycemia in patients with type 2 diabetes mellitus treated with antidiabetic agents, such as insulin and/or insulin secretagogues (e.g., sulfonylureas). In clinical trials, lorcaserin use was associated with reports of hypoglycemia. Blood glucose monitoring is warranted in patients with type 2 diabetes prior to starting and during lorcaserin treatment. Dosage adjustments of anti-diabetic medications should be considered. If a patient develops hypoglycemia during treatment, adjust anti-diabetic drug regimen accordingly. Of note, lorcaserin has not been studied in combination with insulin.
Losartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Mafenide: (Moderate) Monitor blood glucose during concomitant metformin and sulfonamide use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Mecasermin, Recombinant, rh-IGF-1: (Moderate) Use caution in combining mecasermin, recombinant, rh-IGF-1 or mecasermin rinfabate (rh-IGF-1/rh-IGFBP-3) with antidiabetic agents. Patients should be advised to eat within 20 minutes of mecasermin administration. Glucose monitoring is important when initializing or adjusting mecasermin therapies, when adjusting concomitant antidiabetic therapy, and in the event of hypoglycemic symptoms. An increased risk for hypoglycemia is possible. The hypoglycemic effect induced by IGF-1 activity may be exacerbated. The amino acid sequence of mecasermin (rh-IGF-1) is approximately 50 percent homologous to insulin and cross binding with either receptor is possible. Treatment with mecasermin has been shown to improve insulin sensitivity and to improve glycemic control in patients with either Type 1 or Type 2 diabetes mellitus when used alone or in conjunction with insulins.
Medroxyprogesterone: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Meglitinides: (Moderate) Use of metformin with a meglitinide ("glinide") may increase the risk of hypoglycemia. Meglitinides are insulin secretagogues and are known to cause hypoglycemia. To manage hypoglycemic risk, lower doses of the meglitinide may be needed. Monitor blood sugar.
Memantine: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Drugs that are eliminated by renal tubular secretion (e.g., memantine) may decrease metformin elimination by competing for common renal tubular transport systems. It should be noted that in a pharmacokinetic study in which memantine and glyburide; metformin (Glucovance) were coadministered, the pharmacokinetics of memantine, metformin, or glyburide were not altered. Regardless, careful patient monitoring is recommended.
Metformin; Repaglinide: (Moderate) Use of metformin with a meglitinide ("glinide") may increase the risk of hypoglycemia. Meglitinides are insulin secretagogues and are known to cause hypoglycemia. To manage hypoglycemic risk, lower doses of the meglitinide may be needed. Monitor blood sugar.
Methamphetamine: (Moderate) Monitor for loss of glycemic control when amphetamines are administered to patients taking antidiabetic agents. Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Sympathomimetic agents, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells.
Methazolamide: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Methyclothiazide: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Methyltestosterone: (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Metolazone: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Metyrapone: (Moderate) In patients taking insulin or other antidiabetic agents, the signs and symptoms of acute metyrapone toxicity (e.g., symptoms of acute adrenal insufficiency) may be aggravated or modified.
Midodrine: (Moderate) Certain medications used concomitantly with metformin may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion, like midodrine, may decrease metformin elimination by competing for common renal tubular transport systems. Careful patient monitoring and dose adjustment of metformin and/or midodrine is recommended.
Moexipril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Monoamine oxidase inhibitors: (Moderate) Monitor blood glucose during concomitant metformin and monoamine oxidase inhibitor (MAOI) use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Naproxen; Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Nateglinide: (Moderate) Use of metformin with a meglitinide ("glinide") may increase the risk of hypoglycemia. Meglitinides are insulin secretagogues and are known to cause hypoglycemia. To manage hypoglycemic risk, lower doses of the meglitinide may be needed. Monitor blood sugar.
Nebivolol; Valsartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Neostigmine; Glycopyrrolate: (Moderate) Coadministration of glycopyrrolate with metformin my increase metformin plasma concentrations, which may lead to increased metformin effects and possible adverse events. If coadministration is necessary, monitor clinical response to metformin and adjust metformin dose accordingly.
Niacin, Niacinamide: (Moderate) Niacin interferes with glucose metabolism and can result in hyperglycemia. Changes in glycemic control can usually be corrected through modification of hypoglycemic therapy. Monitor patients taking antidiabetic agents for changes in glycemic control if niacin is added or deleted to the medication regimen. Dosage adjustments may be necessary.
Niacin; Simvastatin: (Moderate) Niacin interferes with glucose metabolism and can result in hyperglycemia. Changes in glycemic control can usually be corrected through modification of hypoglycemic therapy. Monitor patients taking antidiabetic agents for changes in glycemic control if niacin is added or deleted to the medication regimen. Dosage adjustments may be necessary.
Nicotine: (Minor) Blood glucose concentrations should be monitored more closely whenever a change in either nicotine intake or smoking status occurs; dosage adjustments of metformin may be needed. Nicotine may increase plasma glucose; tobacco smoking is known to aggravate insulin resistance. The cessation of nicotine therapy or tobacco smoking may result in a decrease in blood glucose.
Nifedipine: (Minor) Nifedipine may increase the plasma metformin Cmax and AUC and increase the amount of metformin excreted in the urine. Metformin half-life is unaffected. Nifedipine appears to enhance the absorption of metformin.
Non-Ionic Contrast Media: (Major) Discontinue metformin at the time of, or before, administration of non-ionic contrast media to patients with an eGFR of 30 to 60 mL/minute/1.73 m2, history of liver disease, alcoholism, or heart failure, or who will be administered intra-arterial iodinated contrast. Reevaluate eGFR 48 hours after the imaging procedure; restart metformin if renal function is stable. Iodinated contrast agents appear to increase the risk of metformin-induced lactic acidosis, possibly as a result of worsening renal function.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Norethindrone: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Norethindrone; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Norgestimate; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Norgestrel: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Octreotide: (Moderate) Monitor patients receiving octreotide concomitantly with insulin or other antidiabetic agents for changes in glycemic control and adjust doses of these medications accordingly. Octreotide alters the balance between the counter-regulatory hormones of insulin, glucagon, and growth hormone, which may result in hypoglycemia or hyperglycemia. The hypoglycemia or hyperglycemia which occurs during octreotide acetate therapy is usually mild but may result in overt diabetes mellitus or necessitate dose changes in insulin or other hypoglycemic agents. In patients with concomitant type1 diabetes mellitus, octreotide is likely to affect glucose regulation, and insulin requirements may be reduced. Symptomatic hypoglycemia, which may be severe, has been reported in type 1 diabetic patients. In Type 2 diabetes patients with partially intact insulin reserves, octreotide administration may result in decreases in plasma insulin levels and hyperglycemia.
Olanzapine; Fluoxetine: (Moderate) Monitor blood glucose during concomitant metformin and fluoxetine use; a metformin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Olmesartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Orlistat: (Minor) Weight-loss may affect glycemic control in patients with diabetes mellitus. In many patients, glycemic control may improve. A reduction in dose of oral hypoglycemic medications may be required in some patients taking orlistat. Monitor blood glucose and glycemic control and adjust therapy as clinically indicated.
Oxandrolone: (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Oxymetholone: (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Pasireotide: (Moderate) Monitor blood glucose levels regularly in patients with diabetes, especially when pasireotide treatment is initiated or when the dose is altered. Adjust treatment with antidiabetic agents as clinically indicated. Pasireotide inhibits the secretion of insulin and glucagon. Patients treated with pasireotide may experience either hypoglycemia or hyperglycemia.
Patiromer: (Moderate) Separate the administration of patiromer and metformin by at least 3 hours if concomitant use is necessary. Simultaneous coadministration may reduce gastrointestinal absorption of metformin and reduce its efficacy. Patiromer has been observed to bind some oral medications when given at the same time and separating administration by at least 3 hours has effectively mitigated this risk.
Pegvisomant: (Moderate) Monitor blood glucose levels regularly in patients with diabetes, especially when pegvisomant treatment is initiated or when the dose is altered. Adjust treatment with antidiabetic agents as clinically indicated. Pegvisomant increases sensitivity to insulin by lowering the activity of growth hormone, and in some patients glucose tolerance improves with treatment. Patients with diabetes treated with pegvisomant and antidiabetic agents may be more likely to experience hypoglycemia.
Pentamidine: (Moderate) Pentamidine can be harmful to pancreatic cells. This effect may lead to hypoglycemia acutely, followed by hyperglycemia with prolonged pentamidine therapy. Patients on antidiabetic agents should be monitored for the need for dosage adjustments during the use of pentamidine.
Pentoxifylline: (Moderate) Pentoxiphylline has been used concurrently with antidiabetic agents without observed problems, but it may enhance the hypoglycemic action of antidiabetic agents. Patients should be monitored for changes in glycemic control while receiving pentoxifylline in combination with antidiabetic agents.
Perindopril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Perindopril; Amlodipine: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Phenothiazines: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. When such drugs are administered to a patient receiving metformin, observe the patient closely for loss of blood glucose control. When such drugs are withdrawn from a patient receiving metformin, observe the patient closely for hypoglycemia.
Phentermine; Topiramate: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Phenytoin: (Minor) Phenytoin and other hydantoins have the potential to increase blood glucose and thus interact with antidiabetic agents pharmacodynamically. Monitor blood glucose for changes in glycemic control. Dosage adjustments may be necessary in some patients.
Pioglitazone; Glimepiride: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Prasterone, Dehydroepiandrosterone, DHEA (Dietary Supplements): (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Prasterone, Dehydroepiandrosterone, DHEA (FDA-approved): (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Progesterone: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Progestins: (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Promethazine; Phenylephrine: (Moderate) Sympathomimetic agents and adrenergic agonists tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine, phenylephrine, and other sympathomimetics are administered to patients taking antidiabetic agents. Epinephrine and other sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Propantheline: (Moderate) Propantheline slows GI motility, which may increase the absorption of metformin from the small intestine. A 19% increase in metformin AUC has been reported in studies of this interaction in healthy volunteers. However, no serious side effects resulted.
Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Protease inhibitors: (Moderate) New onset diabetes mellitus, exacerbation of diabetes mellitus, and hyperglycemia due to insulin resistance have been reported with use of anti-retroviral protease inhibitors. Another possible mechanism is impairment of beta-cell function. Onset averaged approximately 63 days after initiating protease inhibitor therapy, but has occurred as early as 4 days after beginning therapy. Diabetic ketoacidosis has occurred in some patients including patients who were not diabetic prior to protease inhibitor treatment. Patients taking antidiabetic therapy should be closely monitored for changes in glycemic control, specifically hyperglycemia, if protease inhibitor therapy is initiated.
Pseudoephedrine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Pseudoephedrine; Triprolidine: (Moderate) Sympathomimetic agents tend to increase blood glucose concentrations when administered systemically. Monitor for loss of glycemic control when pseudoephedrine is administered to patients taking metformin. Sympathomimetics, through stimulation of alpha- and beta- receptors, increase hepatic glucose production and glycogenolysis and inhibit insulin secretion. Also, adrenergic medications may decrease glucose uptake by muscle cells. For treatment of cold symptoms, nasal decongestants may be preferable for short term, limited use (1 to 3 days) as an alternative to systemic decongestants in patients taking medications for diabetes.
Quinapril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Quinolones: (Moderate) Monitor blood glucose carefully when systemic quinolones and antidiabetic agents, including metformin, are coadministered. Discontinue the quinolone if a hypoglycemic reaction occurs and initiate appropriate therapy immediately. Disturbances of blood glucose, including hyperglycemia and hypoglycemia, have been reported in patients treated concomitantly with quinolones and an antidiabetic agent. Hypoglycemia, sometimes resulting in coma, can occur.
Ramipril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Ranolazine: (Major) Limit the dose of metformin to 1,700 mg/day in adults if coadministered with ranolazine 1,000 mg twice daily. Coadministration of metformin with ranolazine 1,000 mg twice daily results in increased exposure to metformin. There is potential for an increased risk for lactic acidosis, which is associated with high metformin concentrations. Doses of metformin do not require reduction if coadministered with ranolazine 500 mg twice daily, as metformin exposure was not significantly increased with this lower dose of ranolazine. Ranolazine inhibits common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2]/multidrug and toxin extrusion [MATE1 and MATE2k]). Consider the benefits and risks of concomitant use of ranolazine with metformin. Monitor blood sugar and for gastrointestinal side effects, and increase monitoring for a risk for lactic acidosis, including renal function and electrolytes/acid-base balance.
Regular Insulin: (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Regular Insulin; Isophane Insulin (NPH): (Moderate) Monitor blood glucose during concomitant metformin and insulin use; an insulin dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Relugolix; Estradiol; Norethindrone acetate: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Repaglinide: (Moderate) Use of metformin with a meglitinide ("glinide") may increase the risk of hypoglycemia. Meglitinides are insulin secretagogues and are known to cause hypoglycemia. To manage hypoglycemic risk, lower doses of the meglitinide may be needed. Monitor blood sugar.
Risdiplam: (Moderate) Concomitant administration of metformin and risdiplam may increase metformin exposure and increase the risk for lactic acidosis. If these drugs are given together, monitor for signs of metformin toxicity; metformin dose adjustments may be needed. Metformin is a human multidrug and toxic extrusion 1 (MATE1) substrate and risdiplam is a an MATE1/2-K inhibitor. MATE inhibitors may decrease metformin elimination by blocking renal tubular secretion.
Sacubitril; Valsartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Salicylates: (Moderate) Monitor blood glucose during concomitant metformin and salicylate use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Segesterone Acetate; Ethinyl Estradiol: (Minor) Monitor blood glucose periodically in patients on metformin for changes in glycemic control when hormone therapy is instituted or discontinued. Estrogens can decrease the hypoglycemic effects of antidiabetic agents by impairing glucose tolerance. Changes in glucose tolerance occur more commonly in patients receiving 50 mcg or more of ethinyl estradiol (or equivalent) per day in combined oral contraceptives (COCs), which are not commonly used in practice since the marketing of lower dose COCs, patches, injections and rings. The presence or absence of a concomitant progestin may influence the significance of any hormonal effect on glucose homeostasis. (Minor) Patients receiving antidiabetic agents like metformin should be closely monitored for signs indicating changes in diabetic control when therapy with progestins is instituted or discontinued. Progestins can impair glucose tolerance.
Sofosbuvir: (Moderate) Closely monitor blood glucose levels if sofosbuvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as sofosbuvir.
Sofosbuvir; Velpatasvir: (Moderate) Closely monitor blood glucose levels if sofosbuvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as sofosbuvir. (Moderate) Closely monitor blood glucose levels if velpatasvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as velpatasvir.
Sofosbuvir; Velpatasvir; Voxilaprevir: (Moderate) Closely monitor blood glucose levels if sofosbuvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as sofosbuvir. (Moderate) Closely monitor blood glucose levels if velpatasvir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as velpatasvir. (Moderate) Closely monitor blood glucose levels if voxilaprevir is administered with antidiabetic agents. Dose adjustments of the antidiabetic agents may be needed. Altered blood glucose control, resulting in serious symptomatic hypoglycemia, has been reported in diabetic patients receiving antidiabetic agents in combination with direct acting antivirals, such as voxilaprevir.
Somapacitan: (Moderate) Patients with diabetes mellitus should be monitored closely during somapacitan therapy. Antidiabetic drugs (e.g., insulin or oral agents) may require adjustment when somapacitan therapy is instituted in these patients. Growth hormones, such as somapacitan, may decrease insulin sensitivity, leading to glucose intolerance and loss of blood glucose control. Therefore, glucose levels should be monitored periodically in all patients treated with somapacitan, especially in those with risk factors for diabetes mellitus.
Somatrogon: (Moderate) Monitor for loss of glycemic control if concomitant use of somatrogon and antidiabetic drugs is necessary; a dose adjustment of the antidiabetic drug may be needed. Growth hormones, such as somatrogon, may decrease insulin sensitivity, leading to glucose intolerance and loss of blood glucose control.
Somatropin, rh-GH: (Moderate) Patients with diabetes mellitus should be monitored closely during somatropin (recombinant rhGH) therapy. Antidiabetic drugs (e.g., insulin or oral agents) may require adjustment when somatropin therapy is instituted in these patients. Growth hormones, such as somatropin, may decrease insulin sensitivity, leading to glucose intolerance and loss of blood glucose control. Therefore, glucose levels should be monitored periodically in all patients treated with somatropin, especially in those with risk factors for diabetes mellitus.
Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Sulfadiazine: (Moderate) Monitor blood glucose during concomitant metformin and sulfonamide use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Moderate) Monitor blood glucose during concomitant metformin and sulfonamide use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sulfasalazine: (Moderate) Monitor blood glucose during concomitant metformin and sulfonamide use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sulfonamides: (Moderate) Monitor blood glucose during concomitant metformin and sulfonamide use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Sulfonylureas: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Tacrolimus: (Moderate) Tacrolimus has been reported to cause hyperglycemia. Furthermore, tacrolimus has been implicated in causing insulin-dependent diabetes mellitus in patients after renal transplantation. Tacrolimus may have direct beta-cell toxicity. Patients should be monitored for worsening of glycemic control if Tacrolimus is initiated in patients receiving antidiabetic agents.
Tafenoquine: (Moderate) Consider the benefits and risks of coadministration of tafenoquine and metformin due to the potential for increased metformin concentrations and lactic acidosis. If coadministration cannot be avoided, monitor for metformin-related toxicities, and consider metformin dosage reduction, if needed. The effect of coadministration of tafenoquine on the pharmacokinetics of OCT2 and MATE substrates, like metformin, in humans is unknown; however, in vitro observations suggest the potential for increased concentrations of OCT2 and MATE substrates. Tafenoquine may interfere with these common renal tubular transport systems involved in the renal elimination of metformin.
Tegaserod: (Moderate) Because tegaserod can enhance gastric emptying in diabetic patients, blood glucose can be affected, which, in turn, may affect the clinical response to antidiabetic agents. The dosing of antidiabetic agents may require adjustment in patients who receive GI prokinetic agents concomitantly.
Telmisartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Telmisartan; Amlodipine: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Testosterone: (Moderate) Changes in insulin sensitivity or glycemic control may occur in patients treated with androgens. In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, may decrease antidiabetic agent dosage requirements. Monitor blood glucose and HbA1C when these drugs are used together.
Thiazide diuretics: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Thyroid hormones: (Minor) Thyroid hormone use may result in increased blood sugar and a loss of glycemic control in some patients. Interactions may or may not be clinically significant at usual replacement doses. Monitor blood sugars carefully when thyroid therapy is added, changed, or discontinued in patients receiving metformin.
Tolazamide: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Tolbutamide: (Moderate) Monitor blood glucose during concomitant sulfonylurea and metformin use; a sulfonylurea dose adjustment may be necessary. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Topiramate: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Torsemide: (Minor) Hyperglycemia has been detected during torsemide therapy, but the incidence is low. Because of this, a potential pharmacodynamic interaction exists between torsemide and all antidiabetic agents, including metformin. Monitor blood glucose.
Trandolapril: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Trandolapril; Verapamil: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin-converting enzyme (ACE) inhibitor use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
Trilaciclib: (Moderate) Concomitant administration of metformin and trilaciclib may increase metformin exposure and increase the risk for lactic acidosis. If these drugs are given together, monitor for signs of metformin toxicity; metformin dose adjustments may be needed. Metformin is an OCT2 and MATE substrate; trilaciclib is an OCT2 and MATE inhibitor that may decrease metformin elimination by blocking renal tubular secretion.
Trospium: (Moderate) Trospium, if used concomitantly with metformin, may increase the risk of lactic acidosis. Cationic drugs that are eliminated by renal tubular secretion like trospium may decrease metformin elimination by competing for common renal tubular transport systems.
Valsartan: (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Monitor blood glucose during concomitant metformin and angiotensin receptor blocker use. Concomitant use may cause an increased blood glucose-lowering effect with risk of hypoglycemia.
Vandetanib: (Moderate) Vandetanib could increase systemic exposure to metformin and may increase the risk for lactic acidosis. Vandetanib increased the plasma concentrations of metformin, which is transported by the renal organic cation transporter type 2 (OCT2). Use caution and closely monitor for toxicities when administering vendetanib with metformin.
Vonoprazan; Amoxicillin; Clarithromycin: (Moderate) The concomitant use of clarithromycin and antidiabetic agents can result in significant hypoglycemia. Careful monitoring of blood glucose is recommended.
Zonisamide: (Moderate) Carbonic anhydrase inhibitors such as zonisamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Use of zonisamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.

Fortamet/Glucophage XR/Glumetza/Metformin Hydrochloride Oral Tab ER: 500mg, 750mg, 1000mg
Glucophage/Metformin Hydrochloride Oral Tab: 500mg, 850mg, 1000mg
Metformin Hydrochloride/Riomet Oral Sol: 5mL, 500mg
RIOMET ER Oral Pwd: 9.46-37.85g
RIOMET ER Oral Susp: 9.46-37.85g

Adults

2,550 mg/day PO for regular-release tablets and oral solution; 2,000 mg/day PO for extended-release tablets and suspension.

Geriatric

Use more than 1,000 mg/day PO with caution in older adults. Adult Max: 2,550 mg/day PO for regular-release tablets and oral solution; 2,000 mg/day PO for extended-release tablets and suspension.

Adolescents

2,000 mg/day PO for regular-release tablets, oral solution, and extended-release suspension; safe and effective use has not been established for extended-release tablets.

Children

10 years and older: 2,000 mg/day PO for regular-release tablets, oral solution, and extended-release suspension; safe and effective use has not been established for extended-release tablets.
Less than 10 years: Safety and efficacy have not been established.

Infants

Safety and efficacy have not been established.

Neonates

Safety and efficacy have not been established.

Metformin is an antihyperglycemic agent that improves glucose tolerance, lowering both basal and postprandial plasma glucose with mechanisms different from other classes of oral antidiabetic agents. Metformin decreases hepatic gluconeogenesis production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and day-long plasma insulin response may actually decrease. Metformin improve glucose utilization in skeletal muscle and adipose tissue by increasing cell membrane glucose transport. This effect may be due to improved binding of insulin to insulin receptors since metformin is not effective in diabetics without some residual functioning pancreatic islet cells. Unlike the sulfonylureas, metformin rarely causes hypoglycemia since it does not significantly change insulin concentrations. An important distinction is that sulfonylureas increase insulin secretion thus making them useful in non-obese patients with type 2 diabetes mellitus (DM) while metformin improves insulin resistance, a common pathophysiologic finding in obese patients with type 2 DM. Metformin causes a 10% to 20% decrease in fatty-acid oxidation and a slight increase in glucose oxidation. Unlike phenformin, metformin does not inhibit the mitochondrial oxidation of lactate unless plasma concentrations of metformin become excessive (i.e., in patients with renal failure) and/or hypoxia is present.
 
Clinically, metformin lowers fasting and postprandial hyperglycemia. The decrease in fasting plasma glucose is approximately 25% to 30%. Unlike oral sulfonylureas, metformin rarely causes hypoglycemia. Thus, metformin demonstrates more of an antihyperglycemic action than a hypoglycemic action. Metformin does not cause weight gain and in fact, may cause a modest weight loss due to drug-induced anorexia. Metformin also decreases plasma VLDL triglycerides resulting in modest decreases in plasma triglycerides and total cholesterol. Patients receiving metformin show a significant improvement in A1C, and a tendency toward improvement in the lipid profile, especially when baseline values are abnormally elevated.
 
Insulin resistance is a primary cause of polycystic ovarian syndrome (PCOS). In PCOS patients, metformin reduces insulin resistance and lowers insulin levels, which lowers serum androgen concentrations, restores normal menstrual cycles and ovulation, and may help to resolve PCOS-associated infertility. Metformin, when administered to lean, overweight, and moderately obese women with PCOS, has been found to significantly reduce serum leuteinizing hormone (LH) and increase follicle stimulating hormone (FSH) and sex hormone binding globulin (SHBG). Serum testosterone concentrations were also found to decrease by approximately 50%.

Metformin is administered orally. The drug is distributed rapidly into peripheral body tissues and fluids and appears to distribute slowly into erythrocytes and to a deep tissue compartment (most likely GI tissues). The highest concentrations are found in the GI tract (10 times the concentrations in the plasma) and lower concentrations in the kidney, liver, and salivary gland tissue. Metformin is negligibly bound to plasma proteins. Metformin is not metabolized by the liver and this fact may explain why the risk of lactic acidosis is much less for metformin than for phenformin (i.e., approximately 10% of patients have an inherited defect in the ability to metabolize phenformin). The drug is excreted by the kidneys, largely unchanged, through an active tubular process. Tubular secretion may be altered by many cationic drugs. Approximately 10% of an oral dose is excreted in the feces, presumably as unabsorbed metformin and about 90% of a dose is excreted by the kidneys within 24 hours. Although the average elimination half-life in the plasma is 6.2 hours in patients with normal renal function, metformin is distributed to and accumulates in red blood cells, which leads to a much longer elimination half-life in the blood (17.6 hours).
 
Affected cytochrome P450 (CYP450) isoenzymes and drug transporters: Organic cationic transporter-2 (OCT2), multidrug and toxin extrusion (MATE1 and MATE2k)
Drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2]/multidrug and toxin extrusion [MATE1 and MATE2k] inhibitors such as ranolazine, vandetanib, dolutegravir, and cimetidine) increase systemic exposure to metformin. Careful patient monitoring and dose adjustment of metformin and/or the potentially interfering drug is recommended with concurrent use.

Oral Route

Metformin Solution (Riomet): The rate and extent of absorption are comparable to regular-release tablets. Peak plasma concentrations are achieved at approximately 2.2 hours. The extent of absorption from the oral solution increases when given with food, and while there is a negligible decrease in Cmax, the Tmax increases from 2.5 to approximately 4 hours. Studies indicate that dose proportionality is lacking with increasing doses due to a decrease in the absorption at higher doses.[60715]
Metformin Regular-release tablets: The bioavailability of 500 mg tablets is 50% to 60% with peak plasma concentrations achieved at approximately 2.5 hours. Food decreases the extent and slightly delays the absorption. Studies indicate that dose proportionality is lacking with increasing doses due to a decrease in the oral absorption at higher doses.[28550]
Metformin Extended-release tablets (Glucophage XR): Using a dual hydrophilic polymer system, metformin is released slowly by diffusion through a gel matrix, allowing for once-daily administration. Peak plasma concentrations are achieved at approximately 7 hours (range, 4 to 8 hours). While peak plasma concentrations are approximately 20% lower for extended-release tablets versus the same dose of regular-release tablets, the extent of absorption from 2,000 mg once-daily of extended-release tablets is similar to the same total daily dose administered as 1,000 mg twice-daily of regular-release tablets. Food increases the extent of absorption of extended-release tablets (as per AUC) by approximately 50%, although Cmax and Tmax are unaltered.[28550]
Metformin Extended-release tablets (Fortamet): Using single-composition osmotic technology (SCOT), metformin is released at a constant rate from an osmotically active tablet core surrounded by a semi-permeable membrane. Peak plasma concentrations are achieved at approximately 6 hours (range 3 to 10 hours). While peak concentrations are higher with Fortamet, the bioavailability of Fortamet 2,000 mg once daily in the evening (as per AUC) is similar to the same total daily dose administered as regular-release tablets 1,000 mg twice daily. When administered with food, the extent of absorption is increased by approximately 60%; also, Cmax is increased by 30%, and Tmax is prolonged (6.1 hours vs. 4 hours). There is a dose-proportional increase in exposure following administration of 1,000 to 2,500 mg.[60711]
Metformin Extended-release tablets (Glumetza): Using gastric-retentive (GR) technology, tablets are designed to remain in the stomach and deliver metformin to the upper GI tract to enhance absorption over an extended period, thus allowing for once-daily dosing. Glumetza tablets must be administered directly after a meal to maximize therapeutic benefit. Peak plasma concentrations from Glumetza 1,000 mg after a meal are achieved in 7 to 8 hours. At usual clinical doses of metformin, steady-state plasma concentrations are reached within 24 to 48 hours and are generally less than 1 mcg/mL. In single and multiple dose studies, once daily Glumetza 1,000 mg provides equivalent systemic exposure (as per AUC), and up to 35% higher Cmax concentrations, when compared to 500 mg twice daily regular-release tablets. Low-fat and high-fat meals increase systemic exposure (as per AUC) by 38% and 73%, respectively, relative to fasting. Both meal types prolong Tmax by approximately 3 hours, but Cmax is not affected.[60714]
Metformin Extended-release suspension (Riomet XR): The mean Cmax is 815 ng/mL and the AUC0-t is 7694 ng/hr/mL following a single oral dose of 750 mg metformin ER suspension taken with high-fat meal, in healthy adult male subjects. The Tmax is achieved with a median value of 4.5 hours and a range of 3.5 to 6.5 hours. In the same study, the administration of metformin ER suspension following a standardized high-fat, high-calorie breakfast (containing approximately 150 kcal from protein, 250 kcal from carbohydrates and 500 kcal from fat) had minimal effect on the AUC of metformin; however, Cmax is decreased by approximately 20% when compared to dosing under fasting condition. The median Tmax is delayed by 1 hour under fed condition compared to fasting condition. The observed elimination half-life (t1/2) is similar under both fasting and fed conditions.

Pregnancy

Premenopausal anovulatory females with insulin resistance (i.e., those with polycystic ovary syndrome (PCOS)) may resume ovulation as a result of metformin therapy; patients may be at risk of conception if adequate contraception is not used in those not desiring to become pregnant. In some cases, metformin is used as an adjunct in PCOS patients to regulate menstrual cycles or to enhance fertility. Metformin is not recommended for routine use during pregnancy.[28550] Metformin does pass through the placenta and the fetus is likely exposed to therapeutic concentrations of metformin.[31404] The American College of Obstetricians and Gynecologists (ACOG) and the American Diabetes Association (ADA) continue to recommend human insulin as the standard of care in women with diabetes mellitus or gestational diabetes mellitus (GDM) requiring medical therapy.[64926] [62358] Per ACOG, in women who decline insulin therapy or are unable to safely administer insulin, metformin is the preferred second-line choice. Per the ADA, metformin may be used to treat GDM as a treatment option; however, no long term safety data are available for any oral agent. Metformin may cause a lower risk of neonatal hypoglycemia and less maternal weight gain than insulin; however, some data suggest that metformin may slightly increase the risk of prematurity. The ADA notes that in some clinical studies, nearly 50% of GDM patients initially treated with metformin have needed the addition of insulin in order to achieve acceptable glucose control.[64926] [62358] Many studies and analyses of metformin use in pregnancy have been published. The data suggest no increase in the rates of expected birth defects or other adverse outcomes in exposed infants and studies comparing metformin to insulin in the treatment of gestational diabetes have generally found no significant differences in glycemic control or pregnancy outcomes.[46193] [46201] [46203]