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Thorazine
Classes
First Generation Antipsychotics
Phenothiazine Antiemetics
Administration
May take with or without food. If stomach upset or nausea occur, take with food.
Tablets: May be crushed prior to administration.
Visually inspect parenteral products for particulate matter and discoloration prior to administration whenever solution and container permit. Lemon-yellow color does not alter potency. However, markedly discolored solutions should be discarded.
NOTE: The intravenous use of chlorpromazine should be limited to the treatment of severe conditions, such as tetanus, severe hiccups, or nausea/vomiting that occurs during surgery.
Monitoring of blood pressure is recommended.
Keep patient in a recumbent position for at least 30 minutes following IV administration to minimize hypotensive effects.
Intermittent IV infusion:
Never inject undiluted chlorpromazine injection into a vein.
Dilute with unpreserved sodium chloride 0.9% for injection to an approximate final concentration of 1 mg/mL (e.g., 50 mg chlorpromazine diluted with 50 mL 0.9% Sodium Chloride for injection).
Infuse IV slowly at a rate not to exceed 1 mg/minute in adults and 0.5 mg/minute in children.
Continuous IV infusion:
Dilute 25 mg to 50 mg in 500 mL to 1000 mL of sodium chloride 0.9% for injection or other compatible large volume IV fluid.
Protect from light.
Infuse IV slowly at a rate prescribed by the physician.
Monitoring of blood pressure is recommended during parenteral administration.
Keep patient in a recumbent position for at least 30 minutes following IV administration to minimize hypotensive effects.
No dilution necessary. However, if irritation occurs after IM administration, further IM doses may be diluted with 0.9% Sodium Chloride Injection or 2% procaine.
Inject slowly and deeply into the upper, outer quadrant of buttock.
Instruct patient on proper use of suppository and avoid excessive handling of the suppository.
Remove the wrapper and moisten the suppository with water prior to insertion. If suppository is too soft because of storage in a warm place, chill in the refrigerator for 30 minutes or run cold water over it before removing the wrapper.
Suppository should be retained in rectum for at least 1—3 hour to ensure maximum benefit.
Adverse Reactions
asphyxia / Early / 0-1.0
neuroleptic malignant syndrome / Delayed / Incidence not known
tardive dyskinesia / Delayed / Incidence not known
cerebral edema / Early / Incidence not known
seizures / Delayed / Incidence not known
ileus / Delayed / Incidence not known
pancytopenia / Delayed / Incidence not known
hemolytic anemia / Delayed / Incidence not known
aplastic anemia / Delayed / Incidence not known
agranulocytosis / Delayed / Incidence not known
toxic epidermal necrolysis / Delayed / Incidence not known
exfoliative dermatitis / Delayed / Incidence not known
corneal opacification / Delayed / Incidence not known
visual impairment / Early / Incidence not known
retinopathy / Delayed / Incidence not known
bronchospasm / Rapid / Incidence not known
angioedema / Rapid / Incidence not known
anaphylactoid reactions / Rapid / Incidence not known
laryngeal edema / Rapid / Incidence not known
torsade de pointes / Rapid / Incidence not known
ventricular tachycardia / Early / Incidence not known
SIADH / Delayed / Incidence not known
water intoxication / Delayed / Incidence not known
lupus-like symptoms / Delayed / Incidence not known
stroke / Early / Incidence not known
constipation / Delayed / 1.0-10.0
jaundice / Delayed / 1.0-2.0
pseudoparkinsonism / Delayed / Incidence not known
akathisia / Delayed / Incidence not known
dystonic reaction / Delayed / Incidence not known
psychosis / Early / Incidence not known
dysphagia / Delayed / Incidence not known
cholestasis / Delayed / Incidence not known
hepatitis / Delayed / Incidence not known
elevated hepatic enzymes / Delayed / Incidence not known
leukopenia / Delayed / Incidence not known
thrombocytopenia / Delayed / Incidence not known
eosinophilia / Delayed / Incidence not known
neutropenia / Delayed / Incidence not known
contact dermatitis / Delayed / Incidence not known
blurred vision / Early / Incidence not known
QT prolongation / Rapid / Incidence not known
hypotension / Rapid / Incidence not known
sinus tachycardia / Rapid / Incidence not known
orthostatic hypotension / Delayed / Incidence not known
impotence (erectile dysfunction) / Delayed / Incidence not known
galactorrhea / Delayed / Incidence not known
hyperprolactinemia / Delayed / Incidence not known
ejaculation dysfunction / Delayed / Incidence not known
priapism / Early / Incidence not known
urinary retention / Early / Incidence not known
infertility / Delayed / Incidence not known
hyponatremia / Delayed / Incidence not known
hypoglycemia / Early / Incidence not known
hyperglycemia / Delayed / Incidence not known
glycosuria / Early / Incidence not known
peripheral edema / Delayed / Incidence not known
hyperthermia / Delayed / Incidence not known
photosensitivity / Delayed / 1.0-10.0
skin hyperpigmentation / Delayed / 0-1.0
drowsiness / Early / 10.0
xerostomia / Early / 10.0
dizziness / Early / Incidence not known
headache / Early / Incidence not known
restlessness / Early / Incidence not known
appetite stimulation / Delayed / Incidence not known
nausea / Early / Incidence not known
weight gain / Delayed / Incidence not known
fever / Early / Incidence not known
purpura / Delayed / Incidence not known
mydriasis / Early / Incidence not known
miosis / Early / Incidence not known
urticaria / Rapid / Incidence not known
libido decrease / Delayed / Incidence not known
menstrual irregularity / Delayed / Incidence not known
mastalgia / Delayed / Incidence not known
gynecomastia / Delayed / Incidence not known
polydipsia / Early / Incidence not known
nasal congestion / Early / Incidence not known
hypothermia / Delayed / Incidence not known
Boxed Warning
Geriatric patients may be more susceptible to the actions and adverse effects of phenothiazines, including tardive dyskinesia, dystonias, orthostatic hypotension, anticholinergic effects, and risk for falls and fractures. Initiate treatment with lower doses followed by careful dosage titration and close monitoring. Antipsychotics are not approved for the treatment of dementia-related psychosis in geriatric patients and the use of phenothiazines in this population should be avoided if possible due to an increase in morbidity and mortality in elderly patients with dementia receiving antipsychotics. Deaths have typically resulted from heart failure, sudden death, or infections. An increased incidence of cerebrovascular adverse events (e.g., stroke, transient ischemic attack), including fatal events, has also been reported. The Beers Criteria consider antipsychotics to be potentially inappropriate medications (PIMs) in elderly patients and should be avoided except for treating schizophrenia, bipolar disorder, or short-term antiemetic use during chemotherapy. The Beers panel recommends avoiding chlorpromazine in geriatric patients with delirium, dementia, lower urinary tract symptoms/benign prostatic hyperplasia in men, syncope, or Parkinson's disease. Non-pharmacological strategies are first-line options for treating delirium- or dementia-related behavioral problems unless they have failed or are not possible and the patient is a substantial threat to self or others. If antipsychotic use is necessary in geriatrics with a history of falls or fractures, consider reducing the use of other CNS depressants and implement other fall risk strategies. Due to the potential for antipsychotic-induced hyponatremia and SIADH, sodium levels should be closely monitored when chlorpromazine is initiated and after dose changes. According to the federal Omnibus Budget Reconciliation Act (OBRA) regulations in residents of long-term care facilities, antipsychotic therapy should only be initiated in a patient with behavioral or psychological symptoms of dementia (BPSD) when the patient is a danger to self or others or has symptoms due to mania or psychosis. For acute conditions persisting beyond 7 days, appropriate non-pharmacologic interventions must be attempted, unless clinically contraindicated and documented. OBRA provides general dosing guidance for antipsychotic treatment of BPSD. Antipsychotics are subject to periodic review for effectiveness, medical necessity, gradual dose reduction (GDR), or rationale for continued use. Refer to the OBRA guidelines for complete information.
Common Brand Names
Thorazine
Dea Class
Rx
Description
Oral and parenteral phenothiazine antipsychotic; potencies of other antipsychotics are compared to oral chlorpromazine 100 mg
Primarily used as an antipsychotic; occastionally used for presurgical anxiolytic, as an antiemetic, and for treatment of intractable hiccups
Boxed warning regarding an increased risk of death in elderly patients with dementia
Dosage And Indications
OUTPATIENTS WITH MILD TO MODERATE SYMPTOMS: Initially, 10 mg PO 3 to 4 times per day or 25 mg PO 2 to 3 times per day. OUTPATIENTS WITH SEVERE SYMPTOMS: Initially, 25 mg PO 3 times per day. After 1 or 2 days, the daily dosage may be increased by 20 to 50 mg at semi-weekly intervals until the patient becomes calm and cooperative. FOR PROMPT CONTROL OF SEVERE SYMPTOMS: The initial treatment should be with intramuscular chlorpromazine; oral administration should be used for subsequent doses in the range of 25 to 50 mg PO 3 times per day. ACUTE SCHIZOPHRENIA IN HOSPITALIZED PATIENTS: Initially, use chlorpromazine intramuscularly until the patient is controlled and cooperative, which generally occurs within 24 to 48 hours. Thereafter, oral doses may be substituted and increased until the patient is calm; total dosage of 500 mg/day is generally sufficient. While gradual increases up to 2,000 mg/day or more may be necessary, the risks generally outweigh the benefits when exceeding 1,000 mg/day for extended periods. When treating psychotic disorders, the dose should be gradually increased until symptoms are controlled. Maximal improvement may not be seen for weeks to months. When the optimal dosage is reached, continue it for 2 weeks then gradually reduce the dosage to the lowest effective maintenance level. A daily dosage of 200 mg is not unusual. Some patients require higher dosages (e.g., 800 mg/day) such as hospitalized patients being discharged. ELDERLY, EMACIATED, OR DEBILITATED ADULTS: In general, dosage levels should be lower. Elderly patients appear to be more susceptible to hypotension and neuromuscular reactions; therefore, close observation is recommended. The dosage should be individualized based on response and tolerability. Dosage should be increased more gradually in elderly patients.
10 to 25 mg PO every 4 to 6 hours as needed. Increase if necessary.
0.55 mg/kg PO every 4 to 6 hours as needed.
Initially, 25 mg IM. If no hypotension occurs, administer 25 to 50 mg IM every 3 to 4 hours as needed until vomiting stops. Then, switch to oral therapy.
Initially, 12.5 mg IM. If no hypotension occurs, may repeat once, 30 minutes after the initial dose. The dosage for treating nausea/vomiting during surgical procedures is lower secondary to prolongation and intensification of the effects of anesthetics by chlorpromazine.
The recommended dose is 0.55 mg/kg IM, repeated every 6 to 8 hours as needed. The duration of IM dosage effect may last up to 12 hours in children. Switch to oral therapy as soon as possible. Do not exceed the following maximum IM daily dose limits: Max: If the child is younger than 5 years (less than 22.7 kg), do not exceed 40 mg/day. If child is 5 to 12 years (22.7 to 45.5 kg), do not exceed 75 mg/day.
Initially, 0.25 mg/kg IM. If no hypotension occurs, may repeat once, 30 minutes after the initial dose. The dosage for treating nausea/vomiting during surgical procedures is lower secondary to prolongation and intensification of the effects of anesthetics by chlorpromazine.
Give 2 mg IV after dosage dilution to a concentration of 1 mg/mL with 0.9% Sodium Chloride injection, and administer IV over at least 2 minutes. May repeat at 2 minute intervals as needed. The total dosage administered via fractional IV injections must not exceed 25 mg.
Give 1 mg IV after dosage dilution to 1 mg/mL with 0.9% Sodium Chloride injection, and administer IV over at least 2 minutes (i.e, rate should not exceed 0.5 mg/minute). May repeat at 2 minute intervals as needed. The total dosage administered via fractional IV injections must not exceed 0.25 mg/kg.
NOTE: This drug is discontinued in the U.S. 50 to 100 mg PR every 6 to 8 hours, as needed.
NOTE: This drug is discontinued in the U.S. 1.1 mg/kg PR every 6 to 8 hours, as needed.
25 to 50 mg IM or IV every 6 to 8 hours; usually given in conjunction with barbiturates. If the IV route is used, follow manufacturer directions for dosage dilution to 1 mg/mL with 0.9% Sodium Chloride for injection and administer dose via IV infusion at a rate no faster than 1 mg/minute.
0.55 mg/kg IV or IM every 6 to 8 hours. If the IV route is used, follow manufacturer directions for dosage dilution to 1 mg/mL with NS and administer dose via IV infusion at a rate no faster than 0.5 mg/minute. Do not exceed the following maximum daily dose limits: If child weighs less than 22.7 kg, do not exceed 40 mg/day. If child weighs 22.7 to 45.5 kg, do not exceed 75 mg/day, except in severe cases.
25 to 50 mg PO 3 to 4 times daily. If symptoms persist for 2 to 3 days, parenteral therapy is indicated.
If after 2 to 3 days there is no response to oral therapy, a single dose of 25 to 50 mg IM may be administered.
If symptoms persist despite IM dosing, a slow IV infusion may be used. The patient should remain flat in bed during the entire infusion, with blood pressure closely monitored. Add 25 to 50 mg of chlorpromazine injection to 500 to 1000 mL of 0.9% Sodium Chloride for injection; administer slowly IV at a rate specified by the prescriber. Do not exceed an IV rate of 1 mg/minute. Discontinue treatment when the infusion is completed.
25 to 50 mg PO 3 to 4 times per day. Treatment usually continues for several weeks; a few patients may require more prolonged treatment.
25 mg IM 3 to 4 times per day until the patient can take oral therapy.
FOR PROMPT CONTROL OF SEVERE SYMPTOMS: 25 mg IM; may repeat in 1 hour if necessary. Subsequent doses should be oral. ACUTE SCHIZOPHRENIC HOSPITALIZED PATIENTS: 25 mg IM. If needed, give an additional 25 to 50 mg IM in 1 hour. Increase subsequent IM doses gradually over several days, up to 400 mg every 4 to 6 hours in exceptionally severe cases until patient is controlled. Usually the patient becomes quiet and cooperative within 24 to 48 hours and oral doses may be substituted.
Initially, 0.55 mg/kg/dose PO every 4 to 6 hours, as needed. Increase gradually every 3 to 4 days as required to control symptoms. If hospitalized, high dosages (i.e., 50 to 100 mg/day or up to 200 mg/day in older children) may be required to treat severe disturbances or psychotic conditions. Dosage must be individualized according to the degree of mental and emotional disturbance exhibited by the patient. In all cases, the lowest effective dosage should be determined for each patient. Continue the titrated effective dose for at least 2 weeks, then gradually reduce the dosage to the lowest effective dose that controls symptoms. NOTE: Behaviors may consist of some or all of the following symptoms (combativeness, impulsivity, attention deficit/hyperactivity, aggression, mood lability, and frustration) which are out of proportion to immediate provocations.
0.55 mg/kg of body weight IM every 6 to 8 hours, as needed. For children younger than 5 years (less than 22.7 kg), total maximum IM dosage is 40 mg/day. For children aged 5 to 12 years (22.7 to 45.5 kg), total maximum IM dosage is 75 mg/day, except in unmanageable cases. Convert to oral therapy as soon as possible. NOTE: Behaviors may consist of some or all of the following symptoms (combativeness, impulsivity, attention deficit/hyperactivity, aggression, mood lability, and frustration) which are out of proportion to immediate provocations.
12.5 mg IV as a single dose. Guidelines classify chlorpromazine as having probable efficacy for the treatment of acute migraine.
Chlorpromazine is not commonly used or recommended in treatment guidelines, due to its pharmacologic profile. A single dose of 25 mg IV, IM, or PO has been recommended for agitated, intensive-care unit patients who require prompt sedation. Repeat doses should be based on clinical response. If the IV route is used, follow manufacturer directions for dosage dilution to 1 mg/mL with 0.9% Sodium Chloride and administer dose via IV infusion at a rate no faster than 1 mg/minute. Keep patient recumbent for the duration of the infusion and for 30 minutes after completion of the dose.
NOTE: The use of chlorpromazine in infants under the age of 6 months should be limited to illnesses where the use of the medication could be potentially lifesaving.
NOTE: Although chlorpromazine is included in current guidelines established by the American Academy of Pediatrics, its use is limited due to occasional adverse effects such as hypothermia, decreased seizure threshold, and eosinophilia. Intramuscular or Oral dosage Neonates
0.55 to 0.7 mg/kg IM or PO every 6 hours has been successful in controlling CNS and GI symptoms of neonatal withdrawal syndrome. In one study, chlorpromazine provided adequate sedation and control of irritability and tremors in 250 cases of neonatal heroin withdrawal.
Initially, 10 to 25 mg PO once daily or twice daily. Gradual titration of no more than 10 to 25 mg/day every 4 to 7 days is recommended. Administer daily dosages in 2 to 4 divided doses in order to control symptoms. Antipsychotics are not FDA-approved for this indication and the labeling of all antipsychotics contains a boxed warning noting an increased risk of death in geriatric patients being treated for behavioral problems associated with dementia. The federal Omnibus Budget Reconciliation Act (OBRA) regulates the use of antipsychotics in long-term care facility (LTCF) residents with dementia-related behavioral symptoms. OBRA Max: 75 mg/day PO in patients meeting the OBRA criteria for treatment, except when documentation is provided showing that higher doses are necessary to maintain or improve the resident's functional status. In addition, the facility must attempt a gradual dose reduction (GDR) in 2 separate quarters, at least 1 month apart, within the first year of admission to the facility or after the facility has initiated an antipsychotic, unless clinically contraindicated. After the first year, a GDR must be attempted annually unless clinically contraindicated. The GDR may be considered clinically contraindicated if the target symptoms returned or worsened after the most recent GDR attempt within the facility and the physician has documented justification for why attempting additional dose reductions at that time would likely impair the resident's function or increase distressed behavior.
10 mg to 25 mg PO every 4 to 6 hours as needed. Per ACOG, chlorpromazine is a last-line treatment option for nausea and vomiting of pregnancy in patients who have failed other therapies.
25 mg to 50 mg IM or IV every 4 to 6 hours as needed. Per ACOG, chlorpromazine is a last-line treatment option for nausea and vomiting of pregnancy in patients who have failed other therapies.
†Indicates off-label use
Dosing Considerations
Specific guidelines for dosage adjustments in hepatic impairment are not available. Use with caution, patients with hepatic disease may have decreased drug metabolism. Patients who develop jaundice secondary to chlorpromazine use should have therapy discontinued.
Renal ImpairmentSpecific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed. Chlorpromazine is not removed by hemodialysis.
Drug Interactions
Abarelix: (Minor) Abarelix can cause QT prolongation. In a single, active-controlled, clinical study comparing abarelix to LHRH agonist plus nonsteroidal antiandrogen, periodic electrocardiograms were performed. Both therapies prolonged the mean QTc interval by >10 msec from baseline. In approximately 20% of 340 patients, the QTc increased more than 30 milliseconds from baseline or the end-of-treatment QTc values were more than 450 milliseconds. The effect of abarelix on the QT interval may be due to androgen deprivation or other variables, as similar effects were seen in men that received a gonadotropin-releasing hormone (GnRH) agonist with a nonsteroidal antiandrogen. Patients with a baseline QTc value greater than 450 milliseconds may not be appropriate candidates for abarelix receipt. Prescribers need to weigh the potential benefits and risks of abarelix use in patients with prolonged QT syndrome or in patients taking other drugs that may prolong the QT interval. Agents with a possible risk for QT prolongation and TdP include phenothiazines.
Acarbose: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Acetaminophen; Aspirin; Diphenhydramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as diphenhydramine. Patients should be informed to read non-prescription allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Caffeine; Dihydrocodeine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Acetaminophen; Caffeine; Pyrilamine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as pyrilamine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Chlorpheniramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Acetaminophen; Codeine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as doxylamine. Patients should be informed to read non-prescription motion sickness, allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Acetaminophen; Dichloralphenazone; Isometheptene: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as dichloralphenazone. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
Acetaminophen; Diphenhydramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as diphenhydramine. Patients should be informed to read non-prescription allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Guaifenesin; Phenylephrine: (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Acetaminophen; Hydrocodone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Acetaminophen; Oxycodone: (Major) Concomitant use of oxycodone with phenothiazines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medication with phenothiazines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Monitor for signs of hypotension after starting or titrating the dosage of oxycodone. There is an increased risk of severe hypotension in patients whose ability to maintain blood pressure has already been compromised by concurrent administration of phenothiazines.
Acetaminophen; Pamabrom; Pyrilamine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as pyrilamine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Acetaminophen; Phenylephrine: (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Adagrasib: (Major) Concomitant use of adagrasib and chlorpromazine increases the risk of QT/QTc prolongation, torsade de pointes (TdP), and other chlorpromazine-related adverse reactions. Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. If concomitant use is necessary, consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, and monitor for an increase in other chlorpromazine-related adverse reactions, including anticholinergic effects, orthostasis, and somnolence. Chlorpromazine is a CYP2D6 substrate and adagrasib is a moderate CYP2D6 inhibitor.
Alfentanil: (Moderate) Concomitant use of alfentanil with other CNS depressants, including the phenothiazines, can potentiate the effects of alfentanil on respiration, alertness, and blood pressure. A dose reduction of one or both drugs may be warranted.
Alfuzosin: (Major) Due to a possible risk for QT prolongation and torsade de pointes (TdP), alfuzosin and chlorpromazine should be used together cautiously. Based on electrophysiology studies performed by the manufacturer, alfuzosin may prolong the QT interval in a dose-dependent manner. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Concurrent use may result in additive QT prolongation.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Alogliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Alogliptin; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. (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.
Alogliptin; Pioglitazone: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Alosetron: (Moderate) Alosetron, if combined with drugs that possess anticholinergic properties like phenothiazines, may seriously worsen constipation, leading to events such as GI obstruction/impaction or paralytic ileus.
Alpha-glucosidase Inhibitors: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Alprazolam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Aluminum Hydroxide: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
Aluminum Hydroxide; Magnesium Carbonate: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
Aluminum Hydroxide; Magnesium Hydroxide: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
Aluminum Hydroxide; Magnesium Trisilicate: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
Amantadine: (Moderate) Although the mechanism of amantadine is not clear, it may potentiate the actions of dopamine. Since phenothiazines are dopamine antagonists, these drugs are best avoided when possible in patients with Parkinson's disease who require amantadine therapy. Also, the anticholinergic effects of phenothiazines can be additive to those of amantadine.
Amifampridine: (Major) Carefully consider the need for concomitant treatment with phenothiazines and amifampridine, as coadministration may increase the risk of seizures. Consider an alternative to the phenothiazine. If coadministration occurs, closely monitor patients for seizure activity. Seizures have been observed in patients without a history of seizures taking amifampridine at recommended doses. Phenothiazines may lower seizure threshold and should be used with caution with concomitant medications which may also affect seizure threshold.
Amikacin: (Minor) When used for the treatment of nausea and vomiting, antiemetic phenothiazines may effectively mask symptoms that are associated with ototoxicity induced by the aminoglycosides.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Aminoglycosides: (Minor) When used for the treatment of nausea and vomiting, antiemetic phenothiazines may effectively mask symptoms that are associated with ototoxicity induced by the aminoglycosides.
Aminolevulinic Acid: (Moderate) Phenothiazines may increase the photosensitizing effects of photosensitizing agents used in photodynamic therapy. Patients should limit ultra-violet exposure.
Amiodarone: (Major) Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. Amiodarone, a Class III antiarrhythmic agent, is associated with a well-established risk of QT prolongation and TdP. Although the frequency of TdP is less with amiodarone than with other Class III agents, amiodarone is still associated with a risk of TdP. Due to the extremely long half-life of amiodarone, a drug interaction is possible for days to weeks after discontinuation of amiodarone.
Amisulpride: (Major) Monitor ECGs for QT prolongation when amisulpride is administered with chlorpromazine. Amisulpride causes dose- and concentration- dependent QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Amitriptyline: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Amobarbital: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Amoxapine: (Moderate) Use caution during coadministration of amoxapine and chlorpromazine. Amoxapine exhibits some antipsychotic activity and may increase the risk of tardive dyskinesia or neuroleptic malignant syndrome (NMS) when antipsychotics are given concurrently. CNS effects, orthostatic hypotension, anticholinergic effects, and lowering of seizure threshold are potential problems with the combined use of amoxapine and chlorpromazine.
Amoxicillin; Clarithromycin; Omeprazole: (Major) Concurrent use of chlorpromazine and clarithromycin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Both clarithromycin and chlorpromazine are specifically associated with an established risk of QT prolongation and TdP.
Anagrelide: (Major) Torsades de pointes (TdP) and ventricular tachycardia have been reported during post-marketing use of anagrelide. A cardiovascular examination, including an ECG, should be obtained in all patients prior to initiating anagrelide therapy. Monitor patients during anagrelide therapy for cardiovascular effects and evaluate as necessary. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with anagrelide include chlorpromazine.
Antacids: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
Anticholinergics: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Anxiolytics; Sedatives; and Hypnotics: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered with other CNS depressant drugs and they should be used cautiously with anxiolytic, sedative, and hypnotics. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of hypnotics and other CNS depressants than with use of a hypnotic alone.
Apomorphine: (Major) Avoid use of apomorphine with chlorpromazine due to an increased risk for QT prolongation and torsade de pointes (TdP). Also, the effectiveness of either agent may be decreased due to opposing effects on dopamine; consider if an atypical antipsychotic would be a suitable alternative to chlorpromazine. Additive CNS depression is also possible. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP at therapeutic doses. Dose-related QTc prolongation is associated with therapeutic apomorphine exposure.
Apraclonidine: (Minor) No specific drug interactions were identified with systemic agents and apraclonidine during clinical trials. Theoretically, apraclonidine might potentiate the effects of CNS depressant drugs such as phenothiazines.
Aripiprazole: (Major) Avoid concomitant use of aripiprazole and chlorpromazine. If use is necessary in patients who are receiving both a CYP3A inhibitor plus chlorpromazine, an aripiprazole dosage reduction may be required. Dosing recommendations vary based on aripiprazole dosage form and CYP3A inhibitor strength. See prescribing information for details. Concomitant use may increase the risk for CNS depression, extrapyramidal symptoms (EPS), QT prolongation and torsade de pointes (TdP), and may increase aripiprazole exposure and the risk for other aripiprazole-related adverse effects. Aripiprazole is a CYP2D6 and CYP3A substrate; chlorpromazine is a moderate CYP2D6 inhibitor. Both medications have been associated with CNS depression, EPS, QT prolongation, and TdP.
Arsenic Trioxide: (Major) If possible, drugs that are known to prolong the QT interval should be discontinued prior to initiating arsenic trioxide therapy. QT prolongation should be expected with the administration of arsenic trioxide. Torsade de pointes (TdP) and complete atrioventricular block have been reported. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously with arsenic trioxide include chlorpromazine. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Artemether; Lumefantrine: (Major) Although there are no studies examining the effects of artemether; lumefantrine in patients receiving other QT prolonging drugs, such as chlorpromazine, coadministration may result in additive QT prolongation. Concomitant use of artemether; lumefantrine with other drugs that prolong the QT interval should be avoided. Consider ECG monitoring if chlorpromazine must be used with or after artemether; lumefantrine treatment. (Major) Artemether; lumefantrine is an inhibitor of and chlorpromazine is metabolized by the CYP2D6 isoenzyme; therefore, coadministration may lead to increased chlorpromazine concentrations. Furthermore, although there are no studies examining the effects of artemether; lumefantrine in patients receiving other QT prolonging drugs, coadministration of such drugs may result in additive QT prolongation. Concomitant use of artemether; lumefantrine with drugs that may prolong the QT interval, such as chlorpromazine, should be avoided. Consider ECG monitoring if chlorpromazine must be used with or after artemether; lumefantrine treatment.
Articaine; Epinephrine: (Moderate) Monitor blood pressure during concomitant epinephrine and phenothiazine use. Phenothiazines antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by a phenothiazine, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Asenapine: (Major) Asenapine has been associated with QT prolongation. According to the manufacturer of asenapine, the drug should be avoided in combination with other agents also known to have this effect. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP) and should be avoided in combination with asenapine. Coadministration of asenapine with phenothiazines, loxapine, thiothixene, molindone, pimozide, haloperidol, or other atypical agents (e.g., aripiprazole, lurasidone, and others) may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Aspirin, ASA; Caffeine; Orphenadrine: (Moderate) Additive anticholinergic effects may be seen when chlorpromazine is used concomitantly with other drugs having antimuscarinic activity such as orphenadrine. Additive sedation may also occur.
Aspirin, ASA; Carisoprodol: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential for additive hypotension and excessive CNS effects (sedation and dizziness), which can impair the ability to undertake tasks requiring mental alertness.
Aspirin, ASA; Carisoprodol; Codeine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential for additive hypotension and excessive CNS effects (sedation and dizziness), which can impair the ability to undertake tasks requiring mental alertness.
Aspirin, ASA; Oxycodone: (Major) Concomitant use of oxycodone with phenothiazines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medication with phenothiazines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Monitor for signs of hypotension after starting or titrating the dosage of oxycodone. There is an increased risk of severe hypotension in patients whose ability to maintain blood pressure has already been compromised by concurrent administration of phenothiazines.
Atazanavir; Cobicistat: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Atenolol; Chlorthalidone: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Atomoxetine: (Major) Concomitant use of atomoxetine and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Atropine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Atropine; Difenoxin: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur. (Moderate) Diphenoxylate is a synthetic opiate derivative that appears to exert its effect locally and centrally on the smooth muscle cells of the GI tract to inhibit GI motility and slow excess GI propulsion. The effects can be additive to other agents with CNS and anticholinergic effects, such as the phenothiazines. In some cases, constipation might occur, and effects on the CNS or bladder function may also be additive.
Azelastine: (Moderate) An enhanced CNS depressant effect may occur when azelastine is combined with other CNS depressants including phenothiazines.
Azelastine; Fluticasone: (Moderate) An enhanced CNS depressant effect may occur when azelastine is combined with other CNS depressants including phenothiazines.
Azilsartan; Chlorthalidone: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Azithromycin: (Major) Avoid coadministration of azithromycin with chlorpromazine due to the increased risk of QT prolongation. If use together is necessary, obtain an ECG at baseline to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. QT prolongation and torsade de pointes (TdP) have been spontaneously reported during azithromycin postmarketing surveillance. Chlorpromazine is associated with an established risk of QT prolongation and TdP.
Baclofen: (Moderate) Monitor for unusual drowsiness and sedation during coadministration of baclofen and phenothiazines due to the risk for additive CNS depression.
Barbiturates: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Bedaquiline: (Major) Concurrent use of bedaquiline and chlorpromazine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Bedaquiline has been reported to prolong the QT interval. Prior to initiating bedaquiline, obtain serum electrolyte concentrations and a baseline ECG. An ECG should also be performed at least 2, 12, and 24 weeks after starting bedaquiline therapy. Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and TdP.
Belladonna; Opium: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Benzhydrocodone; Acetaminophen: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Benzodiazepines: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Benztropine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Berotralstat: (Moderate) Monitor for an increase in chlorpromazine-related adverse reactions, including QT prolongation, anticholinergic effects, orthostasis, and somnolence, if coadministration with berotralstat is necessary. Concomitant use may increase chlorpromazine exposure. Chlorpromazine is a CYP2D6 substrate and berotralstat is a CYP2D6 inhibitor.
Bethanechol: (Moderate) Drugs that possess antimuscarinic properties, such as chlorpromazine, are pharmacologic opposites of bethanechol. These agents should not be used with bethanechol except when the specific intent is to counteract excessive actions of one or the other.
Bismuth Subcitrate Potassium; Metronidazole; Tetracycline: (Major) Concomitant use of metronidazole and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Bismuth Subsalicylate: (Moderate) Antidiarrheals decrease GI motility. Agents that inhibit intestinal motility or prolong intestinal transit time have been reported to induce toxic megacolon. The concomitant administration of phenothiazines may produce additive effects.
Bismuth Subsalicylate; Metronidazole; Tetracycline: (Major) Concomitant use of metronidazole and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary. (Moderate) Antidiarrheals decrease GI motility. Agents that inhibit intestinal motility or prolong intestinal transit time have been reported to induce toxic megacolon. The concomitant administration of phenothiazines may produce additive effects.
Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Brexpiprazole: (Major) Caution is advisable during concurrent use of brexpiprazole with other antipsychotics such as phenothiazines. The risk of drowsiness, dizziness, hypotension, extrapyramidal symptoms, anticholinergic effects, neuroleptic malignant syndrome, or seizures may be increased during combined use of brexpiprazole and phenothiazines; therefore, it may be advisable to initiate treatment with lower dosages if combination therapy is deemed necessary. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the coadministered antipsychotic agent, with low-potency agents (e.g., thioridazine, chlorpromazine) having an increased likelihood of causing sedation, orthostasis, and anticholinergic effects, and high-potency agents (e.g., fluphenazine) having an increased likelihood of causing extrapyramidal effects. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Bromocriptine: (Major) Avoid concurrent use of phenothiazines and bromocriptine when possible. Bromocriptine may interact with dopamine antagonists such as the phenothiazines. The phenothiazines are noted to result in a decreased efficacy of bromocriptine. The prolactin-lowering effect of bromocriptine is antagonized; the elevation in prolactin levels produced by phenothiazines persists with chronic administration. In addition, bromocriptine, a dopamine agonist, may theoretically diminish the effectiveness of central dopamine antagonists such as the phenothiazines; however, such interactions are not certain.
Brompheniramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as brompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as brompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Brompheniramine; Phenylephrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as brompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Brompheniramine; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as brompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as brompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Bupivacaine; Epinephrine: (Moderate) Monitor blood pressure during concomitant epinephrine and phenothiazine use. Phenothiazines antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by a phenothiazine, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Buprenorphine: (Major) Due to the potential for QT prolongation and additive CNS depressant effects, cautious use and close monitoring are advisable if concurrent use of chlorpromazine and buprenorphine is necessary. Buprenorphine has been associated with QT prolongation and has a possible risk of torsade de pointes (TdP). Chlorpromazine has a possible risk for QT prolongation and TdP. FDA-approved labeling for some buprenorphine products recommend avoiding use with Class 1A and Class III antiarrhythmic medications while other labels recommend avoiding use with any drug that has the potential to prolong the QT interval. If concurrent use of chlorpromazine and buprenorphine is necessary, consider a dose reduction of one or both drugs. Hypotension, profound sedation, coma, respiratory depression, or death may occur during co-administration of buprenorphine and other CNS depressants. Prior to concurrent use of buprenorphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Evaluate the patient's use of alcohol or illicit drugs. It is recommended that the injectable buprenorphine dose be halved for patients who receive other drugs with CNS depressant effects; for the buprenorphine transdermal patch, start with the 5 mcg/hour patch. Monitor patients for sedation or respiratory depression.
Buprenorphine; Naloxone: (Major) Due to the potential for QT prolongation and additive CNS depressant effects, cautious use and close monitoring are advisable if concurrent use of chlorpromazine and buprenorphine is necessary. Buprenorphine has been associated with QT prolongation and has a possible risk of torsade de pointes (TdP). Chlorpromazine has a possible risk for QT prolongation and TdP. FDA-approved labeling for some buprenorphine products recommend avoiding use with Class 1A and Class III antiarrhythmic medications while other labels recommend avoiding use with any drug that has the potential to prolong the QT interval. If concurrent use of chlorpromazine and buprenorphine is necessary, consider a dose reduction of one or both drugs. Hypotension, profound sedation, coma, respiratory depression, or death may occur during co-administration of buprenorphine and other CNS depressants. Prior to concurrent use of buprenorphine in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Evaluate the patient's use of alcohol or illicit drugs. It is recommended that the injectable buprenorphine dose be halved for patients who receive other drugs with CNS depressant effects; for the buprenorphine transdermal patch, start with the 5 mcg/hour patch. Monitor patients for sedation or respiratory depression.
Bupropion: (Major) Bupropion is associated with a dose-related risk of seizures and may have an additive effect with phenothiazines on lowering the seizure threshold. Low initial dosing and slow titration is recommended if this combination must be used. In addition, bupropion is a strong inhibitor of CYP2D6. Dosage reductions of chlorpromazine, a CYP2D6 substrate, may be needed during coadministration with bupropion. Increased serum concentrations of chlorpromazine may result in QT prolongation, somnolence, anticholinergic effects, or orthostasis.
Bupropion; Naltrexone: (Major) Bupropion is associated with a dose-related risk of seizures and may have an additive effect with phenothiazines on lowering the seizure threshold. Low initial dosing and slow titration is recommended if this combination must be used. In addition, bupropion is a strong inhibitor of CYP2D6. Dosage reductions of chlorpromazine, a CYP2D6 substrate, may be needed during coadministration with bupropion. Increased serum concentrations of chlorpromazine may result in QT prolongation, somnolence, anticholinergic effects, or orthostasis. (Moderate) Patients receiving phenothiazines and naltrexone concomitantly have had symptoms of somnolence and lethargy.
Butabarbital: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Butalbital; Acetaminophen: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Butalbital; Acetaminophen; Caffeine: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Butalbital; Acetaminophen; Caffeine; Codeine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Butalbital; Aspirin; Caffeine; Codeine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Butorphanol: (Moderate) Concomitant use of butorphanol with other CNS depressants, such as phenothiazines, can potentiate the effects of butorphanol on respiratory depression, CNS depression, and sedation.
Cabergoline: (Moderate) Cabergoline should generally not be coadministered with phenothiazines due to mutually antagonistic effects on dopaminergic function. The dopamine antagonist action of phenothiazines may diminish the prolactin-lowering ability of cabergoline while the dopamine agonist effects of cabergoline may exacerbate a psychotic disorder, reducing the effectiveness of antipsychotics such as phenothiazines.
Cabotegravir; Rilpivirine: (Major) Concurrent use of chlorpromazine and rilpivirine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. Phenothiazines have also been associated with QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Calcium, Magnesium, Potassium, Sodium Oxybates: (Major) Additive CNS depressant effects may be possible when sodium oxybate is used concurrently with phenothiazines.
Canagliflozin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted.
Canagliflozin; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (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.
Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Cannabidiol: (Moderate) Monitor for excessive sedation and somnolence during coadministration of cannabidiol and phenothiazines. CNS depressants can potentiate the effects of cannabidiol.
Capsaicin; Metaxalone: (Moderate) Phenothiazines can potentiate the CNS-depressant action of skeletal muscle relaxants like metaxalone. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects.
Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Carbidopa; Levodopa: (Major) Avoid concurrent use if possible and consider an atypical antipsychotic as an alternative to the phenothiazine. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors. Due to opposing effects on central dopaminergic activity, phenothiazines and levodopa may interfere with the effectiveness of each other.
Carbidopa; Levodopa; Entacapone: (Major) Avoid concurrent use if possible and consider an atypical antipsychotic as an alternative to the phenothiazine. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors. Due to opposing effects on central dopaminergic activity, phenothiazines and levodopa may interfere with the effectiveness of each other.
Carbinoxamine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as carbinoxamine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Cariprazine: (Major) Avoid use of these drugs together due to duplicative therapeutic effects and additive risks for drowsiness, dizziness, orthostatic hypotension, extrapyramidal symptoms, neuroleptic malignant syndrome, and seizures. Cariprazine, like other antipsychotics, has the potential to impair judgment, thinking, or motor skills. The use of cariprazine with other antipsychotic agents, such as the phenothiazines, would be expected to have additive risks for pharmacologic effects and adverse reactions. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during combined use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Carisoprodol: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential for additive hypotension and excessive CNS
Celecoxib; Tramadol: (Moderate) Concurrent use of tramadol and chlorpromazine should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. In addition, in vitro data suggest that chlorpromazine has CYP2D6 inhibitory effects and has the potential to decrease the metabolism of CYP2D6 substrates such as tramadol. Although the full pharmacologic impact of increased tramadol exposure is unknown, close monitoring for serious adverse effects, such as seizures, is advisable. In addition, serotonin syndrome may occur during use of tramadol with medications that impair its metabolism. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, hyperreflexia, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Because the analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), CYP2D6 inhibition by chlorpromazine may alter the analgesic response to tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and chlorpromazine.
Cenobamate: (Moderate) Monitor for excessive sedation and somnolence during coadministration of cenobamate and a phenothiazine. Concurrent use may result in additive CNS depression.
Central-acting adrenergic agents: (Moderate) Monitor blood pressure and for unusual drowsiness or excessive sedation during concomitant central-acting adrenergic agent and phenothiazine use. Concomitant use increases the risk for additive hypotension and CNS depression.
Ceritinib: (Major) Avoid coadministration of ceritinib with chlorpromazine if possible due to the risk of QT prolongation. If concomitant use is unavoidable, periodically monitor ECGs and electrolytes; an interruption of ceritinib therapy, dose reduction, or discontinuation of therapy may be necessary if QT prolongation occurs. Ceritinib causes concentration-dependent prolongation of the QT interval. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Cetrorelix: (Moderate) Drugs that cause hyperprolactinemia, such as antipsychotics, should not be administered concomitantly with cetrorelix since hyperprolactinemia downregulates the number of pituitary GnRH receptors.
Charcoal: (Major) Phenothiazine absorption is reduced when coadministered with activated charcoal. Concomitant administration of phenothiazines and activated charcoal dietary supplements is not recommended. Activated charcoal may be appropriate in phenothiazine overdose situations, as charcoal absorbs the phenothiazines and also enhances drug elimination.
Chlophedianol; Dexbrompheniramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as dexbrompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as dexchlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlordiazepoxide: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Chlordiazepoxide; Amitriptyline: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression. (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Chlordiazepoxide; Clidinium: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression. (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Chloroquine: (Major) Avoid coadministration of chloroquine with chlorpromazine due to the increased risk of QT prolongation. If use together is necessary, obtain an ECG at baseline to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Chloroquine is associated with an increased risk of QT prolongation and torsade de pointes (TdP); the risk of QT prolongation is increased with higher chloroquine doses. Chlorpromazine is associated with an established risk of QT prolongation and TdP.
Chlorothiazide: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Chlorpheniramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlorpheniramine; Codeine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlorpheniramine; Dextromethorphan: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Chlorpheniramine; Hydrocodone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlorpheniramine; Phenylephrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Chlorpheniramine; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as chlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Chlorpropamide: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure.
Chlorthalidone: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Chlorthalidone; Clonidine: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Chlorzoxazone: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
Cimetidine: (Minor) Cimetidine has been reported to alter the steady-state plasma concentrations of chlorpromazine. It is possible that cimetidine may also reduce the hepatic metabolism of chlorpromazine. Excessive sedation has been reported in a few case reports. There are limited data supporting the clinical significance of this interaction. Another H-2 blocker may be preferred. Monitor the patient for altered clinical response to therapy or excessive sedation if these drugs are co-administered.
Cinacalcet: (Moderate) Monitor for an increase in chlorpromazine-related adverse reactions, including QT prolongation, anticholinergic effects, orthostasis, and somnolence, if coadministration with cinacalcet is necessary. Concomitant use may increase chlorpromazine exposure. Chlorpromazine is a CYP2D6 substrate and cinacalcet is a moderate CYP2D6 inhibitor.
Ciprofloxacin: (Major) Concomitant use of ciprofloxacin and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Cisapride: (Contraindicated) Coadministration of cisapride and chlorpromazine is contraindicated due to the risk for serious adverse events, such as torsade de pointes (TdP). QT prolongation and ventricular arrhythmias, including TdP and death, have been reported with cisapride. Chlorpromazine is also associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Citalopram: (Major) Concurrent use of citalopram and chlorpromazine should be avoided. Citalopram causes dose-dependent QT interval prolongation and chlorpromazine is associated with an established risk of QT prolongation and torsade de pointes (TdP). According to the manufacturer of citalopram, concurrent use of citalopram with other drugs that prolong the QT interval is not recommended. If concurrent therapy is considered essential, ECG monitoring is recommended. Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering selective serotonin reuptake inhibitors (SSRIs) with drugs that are dopamine antagonists such as phenothiazines. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Citalopram is a weak inhibitor of the CYP2D6 pathway and may result in increases in serum phenothiazine concentrations, leading to side effects. Patients receiving a phenothiazine and an SSRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
Clarithromycin: (Major) Concurrent use of chlorpromazine and clarithromycin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Both clarithromycin and chlorpromazine are specifically associated with an established risk of QT prolongation and TdP.
Clemastine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as clemastine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Clindamycin; Tretinoin: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as phenothiazines, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
Clobazam: (Major) A dose reduction of CYP2D6 substrates, such as chlorpromazine, may be necessary during coadministration of clobazam. Clobazam is a weak inhibitor of CYP2D6. Elevated concentrations of chlorpromazine occurring through inhibition of CYP2D6 may increase the risk of QT prolongation, torsade de pointes, or other serious adverse effects. Phenothiazines may lower the seizure threshold and reduce the effectiveness of clobazam as an anticonvulsant.
Clofazimine: (Major) Concomitant use of clofazimine and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Clomipramine: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Clonazepam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Clorazepate: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Clozapine: (Major) Treatment with clozapine has been associated with QT prolongation, torsade de pointes (TdP), cardiac arrest, and sudden death. The manufacturer of clozapine recommends caution during concurrent use with medications known to cause QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). In addition, coadministration of clozapine with phenothiazines may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Cobicistat: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Codeine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Codeine; Guaifenesin: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Codeine; Guaifenesin; Pseudoephedrine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Codeine; Phenylephrine; Promethazine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Major) The use of promethazine, a phenothiazine antiemetic, with phenothiazine antipsychotics such as chlorpromazine should be avoided if possible. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Promethazine has also been associated with QT prolongation. The duplicative actions of the drugs may result in an increased risk for side effects. Coadministration of promethazine and phenothiazine antipsychotics may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. Although the incidence of tardive dyskinesia from these combinations has not been established and data are very limited, the risk may be increased during combined use versus use of an antipsychotic alone. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Codeine; Promethazine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Major) The use of promethazine, a phenothiazine antiemetic, with phenothiazine antipsychotics such as chlorpromazine should be avoided if possible. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Promethazine has also been associated with QT prolongation. The duplicative actions of the drugs may result in an increased risk for side effects. Coadministration of promethazine and phenothiazine antipsychotics may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. Although the incidence of tardive dyskinesia from these combinations has not been established and data are very limited, the risk may be increased during combined use versus use of an antipsychotic alone.
COMT inhibitors: (Major) Due to opposing effects on central dopaminergic activity, phenothiazines and COMT inhibitors may interfere with the effectiveness of each other. Avoid concurrent use if possible and consider an alternative to the phenothiazine. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors.
Crizotinib: (Major) Avoid coadministration of crizotinib with chlorpromazine due to the risk of QT prolongation. If concomitant use is unavoidable, monitor ECGs for QT prolongation and monitor electrolytes. An interruption of therapy, dose reduction, or discontinuation of therapy may be necessary for crizotinib patients if QT prolongation occurs. Crizotinib has been associated with concentration-dependent QT prolongation. Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and torsade de pointes (TdP).
Cyclobenzaprine: (Moderate) Additive anticholinergic effects may be seen when chlorpromazine is used concomitantly with other drugs with antimuscarinic activity such as cyclobenzaprine. Antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive sedation may also occur.
Dantrolene: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as skeletal muscle relaxants. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
Dapagliflozin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted.
Dapagliflozin; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (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.
Dapagliflozin; Saxagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Darunavir; Cobicistat: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Dasatinib: (Major) Due to a possible risk for QT prolongation and torsade de pointes (TdP), dasatinib and chlorpromazine should be used together cautiously. In vitro studies have shown that dasatinib has the potential to prolong the QT interval. Caution is advised when coadministered with other drugs that prolong the QT interval. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Degarelix: (Major) Avoid coadministration of degarelix with chlorpromazine due to the risk of reduced efficacy of degarelix; QT prolongation may also occur. Chlorpromazine can cause hyperprolactinemia, which reduces the number of pituitary gonadotropin releasing hormone (GnRH) receptors; degarelix is a GnRH analog. Additionally, chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Androgen deprivation therapy (i.e., degarelix) may also prolong the QT/QTc interval.
Desflurane: (Major) Halogenated anesthetics should be used cautiously and with close monitoring with chlorpromazine. Halogenated anesthetics can prolong the QT interval. Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. In addition, phenothiazines can potentiate the CNS-depressant action of anesthetics.
Desipramine: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Desmopressin: (Major) Additive hyponatremic effects may be seen in patients treated with desmopressin and drugs associated with water intoxication, hyponatremia, or SIADH including chlorpromazine. Use combination with caution, and monitor patients for signs and symptoms of hyponatremia.
Desogestrel; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Desvenlafaxine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
Deutetrabenazine: (Major) The risk of QT prolongation may be increased with coadministration of deutetrabenazine and chlorpromazine. Deutetrabenazine may prolong the QT interval, but the degree of QT prolongation is not clinically significant when deutetrabenazine is administered within the recommended dosage range. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Monitor for signs and symptoms of neuroleptic malignant syndrome (NMS), restlessness, and agitation. If NMS is diagnosed, immediately discontinue deutetrabenazine, and provide intensive symptomatic treatment and medical monitoring. Recurrence of NMS has been reported with resumption of drug therapy. If akathisia or parkinsonism develops during treatment, the deutetrabenazine dose should be reduced; discontinuation may be required. Deutetrabenazine is a reversible, dopamine depleting drug and chlorpromazine is a dopamine antagonist. Monitor for excessive sedation and somnolence during coadministration of chlorpromazine and deutetrabenazine. Concurrent use may result in additive CNS depression.
Dexbrompheniramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as dexbrompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Dexbrompheniramine; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as dexbrompheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Dexchlorpheniramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as dexchlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as dexchlorpheniramine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Dexmedetomidine: (Major) Concomitant use of dexmedetomidine and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary. In addition, consider a dosage reduction for dexmedetomidine or chlorpromazine during concomitant use due to the risk of additive CNS effects.
Dextromethorphan; Bupropion: (Major) Bupropion is associated with a dose-related risk of seizures and may have an additive effect with phenothiazines on lowering the seizure threshold. Low initial dosing and slow titration is recommended if this combination must be used. In addition, bupropion is a strong inhibitor of CYP2D6. Dosage reductions of chlorpromazine, a CYP2D6 substrate, may be needed during coadministration with bupropion. Increased serum concentrations of chlorpromazine may result in QT prolongation, somnolence, anticholinergic effects, or orthostasis.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as diphenhydramine. Patients should be informed to read non-prescription allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Dextromethorphan; Quinidine: (Contraindicated) Quinidine administration is associated with QT prolongation and torsades de pointes (TdP). Quinidine inhibits CYP2D6 and has QT-prolonging actions; quinidine is contraindicated with other drugs that prolong the QT interval and are metabolized by CYP2D6 as the effects on the QT interval may be increased during concurrent use of these agents. Drugs that prolong the QT and are substrates for CYP2D6 that are contraindicated with quinidine include chlorpromazine.
Diazepam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Dicyclomine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Diethylpropion: (Minor) Use of diethylpropion with phenothiazines may antagonize the anorectic effects of diethylpropion.
Difelikefalin: (Moderate) Monitor for dizziness, somnolence, mental status changes, and gait disturbances if concomitant use of difelikefalin with CNS depressants is necessary. Concomitant use may increase the risk for these adverse reactions.
Dimenhydrinate: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as dimenhydrinate. Patients should be informed to read non-prescription motion sickness, allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Dipeptidyl Peptidase-4 Inhibitors: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Diphenhydramine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as diphenhydramine. Patients should be informed to read non-prescription allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Diphenhydramine; Ibuprofen: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as diphenhydramine. Patients should be informed to read non-prescription allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Diphenhydramine; Naproxen: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as diphenhydramine. Patients should be informed to read non-prescription allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Diphenhydramine; Phenylephrine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as diphenhydramine. Patients should be informed to read non-prescription allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Diphenoxylate; Atropine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur. (Moderate) Diphenoxylate is a synthetic opiate derivative that appears to exert its effect locally and centrally on the smooth muscle cells of the GI tract to inhibit GI motility and slow excess GI propulsion. The effects can be additive to other agents with CNS and anticholinergic effects, such as the phenothiazines. In some cases, constipation might occur, and effects on the CNS or bladder function may also be additive.
Disopyramide: (Major) Avoid use of disopyramide with chlorpromazine if possible due to an increased risk for QT prolongation. Disopyramide administration is associated with QT prolongation and torsade de pointes (TdP). Phenothiazines have been associated with a risk of QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Additive anticholinergic effects are also possible, as both drugs exhibit significant anticholinergic activity.
Dofetilide: (Major) Coadministration of dofetilide and chlorpromazine is not recommended as concurrent use may increase the risk of QT prolongation. Dofetilide, a Class III antiarrhythmic agent, is associated with a well-established risk of QT prolongation and torsade de pointes (TdP). Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Dolasetron: (Major) Due to a possible risk for QT prolongation and torsade de pointes (TdP), dolasetron and chlorpromazine should be used together cautiously. Dolasetron has been associated with a dose-dependent prolongation in the QT, PR, and QRS intervals on an electrocardiogram. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Concurrent use may further increase the risk for QT prolongation.
Dolutegravir; Rilpivirine: (Major) Concurrent use of chlorpromazine and rilpivirine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. Phenothiazines have also been associated with QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Donepezil: (Major) Case reports indicate that QT prolongation and torsade de pointes (TdP) can occur during donepezil therapy. Donepezil is considered a drug with a known risk of TdP. Chlorpromazine has a possible risk for QT prolongation and TdP and should be used cautiously and with close monitoring with donepezil. In addition, conventional antipsychotics with significant anticholinergic effects, such as chlorpromazine, are more likely than other conventional antipsychotics to diminish the therapeutic action of donepezil, and use of an alternative antipsychotic should be considered. Donepezil inhibits acetylcholinesterase, the enzyme responsible for the degradation of acetylcholine, and exerts its therapeutic effect by improving the availability of acetylcholine.
Donepezil; Memantine: (Major) Case reports indicate that QT prolongation and torsade de pointes (TdP) can occur during donepezil therapy. Donepezil is considered a drug with a known risk of TdP. Chlorpromazine has a possible risk for QT prolongation and TdP and should be used cautiously and with close monitoring with donepezil. In addition, conventional antipsychotics with significant anticholinergic effects, such as chlorpromazine, are more likely than other conventional antipsychotics to diminish the therapeutic action of donepezil, and use of an alternative antipsychotic should be considered. Donepezil inhibits acetylcholinesterase, the enzyme responsible for the degradation of acetylcholine, and exerts its therapeutic effect by improving the availability of acetylcholine.
Dopamine: (Moderate) The vasoconstrictive properties of dopamine infusion can be decreased due to the alpha-adrenergic blocking capability of phenothiazines.
Doxepin: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Doxorubicin Liposomal: (Major) Avoid coadministration of chlorpromazine with doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Chlorpromazine is a CYP2D6 inhibitor, and doxorubicin is a major substrate of CYP2D6. Concurrent use of CYP2D6 inhibitors with doxorubicin has resulted in clinically significant interactions.
Doxorubicin: (Major) Avoid coadministration of chlorpromazine with doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Chlorpromazine is a CYP2D6 inhibitor, and doxorubicin is a major substrate of CYP2D6. Concurrent use of CYP2D6 inhibitors with doxorubicin has resulted in clinically significant interactions.
Doxylamine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as doxylamine. Patients should be informed to read non-prescription motion sickness, allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Doxylamine; Pyridoxine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as doxylamine. Patients should be informed to read non-prescription motion sickness, allergy, sleep, and cough and cold product labels carefully for additional interacting antihistamines.
Dronabinol: (Moderate) Use caution if coadministration of phenothiazines with dronabinol is necessary. Administration of dronabinol with phenothiazines (e.g., prochlorperazine) has resulted in improved antiemetic efficacy as compared to either drug alone, without additional toxicity. However, it is also possible that coadministration may result in additive dizziness, confusion, somnolence, and other CNS effects.
Dronedarone: (Contraindicated) Concomitant use of dronedarone and chlorpromazine is contraindicated. Dronedarone is an inhibitor of CYP2D6. Chlorpromazine is a substrate for CYP2D6. Coadministration of dronedarone and chlorpromazine may result in elevated plasma concentrations of chlorpromazine. In addition, chlorpromazine has been established to have a causal association with QT prolongation and Torsade de Pointes (TdP). Dronedarone administration is associated with a dose-related increase in the QTc interval. The increase in QTc is approximately 10 milliseconds at doses of 400 mg twice daily (the FDA-approved dose) and up to 25 milliseconds at doses of 1600 mg twice daily. Although there are no studies examining the effects of dronedarone in patients receiving other QT prolonging drugs, coadministration of such drugs may result in additive QT prolongation and is contraindicated.
Droperidol: (Major) Droperidol should be administered with extreme caution to patients receiving other agents that may prolong the QT interval. Droperidol administration is associated with an established risk for QT prolongation and torsades de pointes (TdP). Any drug known to have potential to prolong the QT interval should not be coadministered with droperidol. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously with droperidol include chlorpromazine.
Drospirenone; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Duloxetine: (Moderate) Caution is advisable during concurrent use of chlorpromazine and serotonin norepinephrine reuptake inhibitors (SNRIs) since elevations in plasma concentrations of chlorpromazine may occur. Phenothiazines are CYP2D6 substrates and duloxetine is a CYP2D6 inhibitor. In addition, chlorpromazine is associated with a possible risk of QT prolongation; therefore, cardiac effects are possible.
Dutasteride; Tamsulosin: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpromazine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Efavirenz: (Major) If possible, avoid coadministration of efavirenz and chlorpromazine, as use of these medications together may increase the risk for QT prolongation and torsade de pointes (TdP). QT prolongation has been observed with use of efavirenz. Although data are limited, the manufacturer of efavirenz recommends an alternative antiretroviral be considered for patients receiving medications with a known risk for TdP. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Efavirenz; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) If possible, avoid coadministration of efavirenz and chlorpromazine, as use of these medications together may increase the risk for QT prolongation and torsade de pointes (TdP). QT prolongation has been observed with use of efavirenz. Although data are limited, the manufacturer of efavirenz recommends an alternative antiretroviral be considered for patients receiving medications with a known risk for TdP. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Major) If possible, avoid coadministration of efavirenz and chlorpromazine, as use of these medications together may increase the risk for QT prolongation and torsade de pointes (TdP). QT prolongation has been observed with use of efavirenz. Although data are limited, the manufacturer of efavirenz recommends an alternative antiretroviral be considered for patients receiving medications with a known risk for TdP. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Eliglustat: (Major) Coadministration of chlorpromazine and eliglustat may result in increased concentrations of the phenothiazine and an increased risk of QT prolongation. If coadministration is necessary, use great caution and monitor closely. Consider reducing the dosage of chlorpromazine and titrating to clinical effect. Chlorpromazine is a CYP2D6 substrate associated with an established risk of QT prolongation. Eliglustat is a CYP2D6 inhibitor that is predicted to cause PR, QRS, and/or QT prolongation at significantly elevated plasma concentrations.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
Empagliflozin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted.
Empagliflozin; Linagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Empagliflozin; Linagliptin; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. (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.
Empagliflozin; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (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.
Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Major) Concurrent use of chlorpromazine and rilpivirine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. Phenothiazines have also been associated with QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Emtricitabine; Rilpivirine; Tenofovir Disoproxil Fumarate: (Major) Concurrent use of chlorpromazine and rilpivirine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. Phenothiazines have also been associated with QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Encorafenib: (Major) Avoid coadministration of encorafenib and chlorpromazine due to QT prolongation. If concurrent use cannot be avoided, monitor ECGs for QT prolongation and monitor electrolytes; correct hypokalemia and hypomagnesemia prior to treatment. Encorafenib is associated with dose-dependent prolongation of the QT interval. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Enteral Feedings: (Major) Chlorpromazine oral concentrate appears to be physically incompatible with enteral feedings. This would include the dilution of the chlorpromazine concentrate in nutritional enteral supplements such as Ensure or Pediasure. These combinations are best avoided. If the patient is taking enteral feedings, separate the times of administration from the oral concentrate doses. Alternatives for dilution should be used. Chlorpromazine oral concentrate may be diluted with tomato or fruit juice, milk, simple syrup, orange syrup, carbonated beverages, coffee, tea, or water. Semi-solid foods, such as applesauce or pudding, may also be used. This interaction does not occur with other dosage forms, only the chlorpromazine oral concentrate.
Entrectinib: (Major) Avoid coadministration of entrectinib with chlorpromazine due to the risk of QT prolongation. Entrectinib has been associated with QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Ephedrine: (Major) Avoid use of ephedrine in patients receiving phenothiazines due to the risk of paradoxical vasodilation. Phenothiazines possess potent alpha-blocking properties, making the use of vasopressors with mixed alpha- and beta-agonist properties inappropriate. If a vasopressor is required, norepinephrine and phenylephrine are most appropriate.
Ephedrine; Guaifenesin: (Major) Avoid use of ephedrine in patients receiving phenothiazines due to the risk of paradoxical vasodilation. Phenothiazines possess potent alpha-blocking properties, making the use of vasopressors with mixed alpha- and beta-agonist properties inappropriate. If a vasopressor is required, norepinephrine and phenylephrine are most appropriate.
Epinephrine: (Moderate) Monitor blood pressure during concomitant epinephrine and phenothiazine use. Phenothiazines antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by a phenothiazine, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Eribulin: (Major) Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP ; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. Drugs with a possible risk for QT prolongation and TdP that should be used with caution with chlorpromazine include eribulin. If coadministration is necessary, ECG monitoring is recommended; closely monitor the patient for QT interval prolongation.
Ertugliflozin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted.
Ertugliflozin; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (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.
Ertugliflozin; Sitagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted. (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Erythro mycin: (Major) Concurrent use of chlorpromazine and erythromycin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Erythromycin is associated with QT prolongation and TdP. Phenothiazines have also been associated with a risk of QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Escitalopram: (Major) Escitalopram has been associated with QT prolongation. Coadministration with other drugs that have a possible risk for QT prolongation and torsade de pointes (TdP), such as chlorpromazine, should be done with caution and close monitoring. In addition, escitalopram modestly inhibits CYP2D6. This can result in increased concentrations of drugs metabolized via the same pathway, including certain conventional antipsychotic agents (phenothiazines). Decreased metabolism of these CYP2D6 substrates may lead to arrhythmias or other clinically important adverse reactions associated with antipsychotic use such as sedation and extrapyramidal symptoms.
Esketamine: (Major) Closely monitor patients receiving esketamine and chlorpromazine for sedation and other CNS depressant effects. Instruct patients who receive a dose of esketamine not to drive or engage in other activities requiring alertness until the next day after a restful sleep.
Estazolam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Eszopiclone: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered with other CNS depressant drugs and they should be used cautiously with anxiolytic, sedative, and hypnotics. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of hypnotics and other CNS depressants than with use of a hypnotic alone.
Ethanol: (Major) Advise patients to avoid alcohol consumption while taking CNS depressants. Alcohol consumption may result in additive CNS depression.
Ethinyl Estradiol; Norelgestromin: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Ethinyl Estradiol; Norethindrone Acetate: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Ethinyl Estradiol; Norgestrel: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Ethiodized Oil: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Ethosuximide: (Moderate) Concomitant use of ethosuximide with phenothiazines can lower the seizure threshold and reduce the effectiveness of ethosuximide as an anticonvulsant. Additive CNS effects, such as drowsiness, may also occur.
Ethynodiol Diacetate; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Etomidate: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as general anesthetics. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
Etonogestrel; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Everolimus: (Moderate) Monitor for an increase in chlorpromazine-related adverse reactions if coadministration with everolimus is necessary. Chlorpromazine is a CYP2D6 substrate and everolimus is a CYP2D6 inhibitor.
Felbamate: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Fenfluramine: (Moderate) Monitor for excessive sedation and somnolence during coadministration of fenfluramine and chlorpromazine. Concurrent use may result in additive CNS depression.
Fentanyl: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Fingolimod: (Major) Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. Drugs with a possible risk for QT prolongation and TdP that should be used with caution with chlorpromazine include fingolimod. Fingolimod initiation results in decreased heart rate and may prolong the QT interval. After the first fingolimod dose, overnight monitoring with continuous ECG in a medical facility is advised for patients taking QT prolonging drugs with a known risk of torsades de pointes (TdP). Fingolimod has not been studied in patients treated with drugs that prolong the QT interval, but drugs that prolong the QT interval have been associated with cases of TdP in patients with bradycardia.
Flavoxate: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Flecainide: (Major) Flecainide is a Class IC antiarrhythmic associated with a possible risk for QT prolongation and/or torsades de pointes (TdP); flecainide increases the QT interval, but largely due to prolongation of the QRS interval. In addition, flecainide is significantly metabolized by CYP2D6 isoenzymes. The coadministration of flecainide with drugs that are CYP2D6 inhibitors may result in increased plasma concentrations of flecainide and an increased risk of QT prolongation. Chlorpromazine prolongs the QT interval and is also a CYP2D6 inhibitor and should be used cautiously with flecainide.
Flibanserin: (Moderate) The concomitant use of flibanserin with CNS depressants, such as phenothiazines, may increase the risk of CNS depression (e.g., dizziness, somnolence) compared to the use of flibanserin alone. Patients should avoid activities requiring full alertness (e.g., operating machinery or driving) until at least 6 hours after each dose and until they know how flibanserin affects them.
Fluconazole: (Major) Concurrent use of chlorpromazine and fluconazole should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Fluconazole has been associated with QT prolongation and rare cases of TdP. Phenothiazines have also been associated with a risk of QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Flucytosine: (Minor) Because of flucytosine's ability to cause significant hematologic toxicity, it should be used cautiously with all bone marrow depressants. These include: carbamazepine, clozapine, phenothiazines, zidovudine, ZDV and other blood dyscrasia-causing medications.
Fluocinolone; Hydroquinone; Tretinoin: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as phenothiazines, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
Fluoxetine: (Major) Fluoxetine is associated with a possible risk of QT prolongation and torsade de pointes (TdP) and chlorpromazine also has an established risk of QT prolongation and TdP. Combination therapy with these agents should be avoided if possible. Fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum phenothiazine concentrations, which may lead to phenothiazine-related side effects such as cardiac side effects, hypotension, CNS sedation, or extrapyramidal symptoms. The effects of fluoxetine on hepatic metabolism of interacting drugs may persist for a time after discontinuation of fluoxetine because of its long elimination half-life.
Fluphenazine: (Moderate) Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Fluphenazine, also a phenothiazine, is associated with a possible risk for QT prolongation. Coadministration of chlorpromazine with other phenothiazines may also increase the risk of phenothiazine-related adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures.
Flurazepam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Fluvoxamine: (Major) Coadministration may increase the risk of QT prolongation, torsade de pointes (TdP), and elevated chlorpromazine concentrations. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. QT prolongation and TdP have been reported during postmarketing use of fluvoxamine. In addition, fluvoxamine is a mild inhibitor of CYP2D6, the primary isoenzyme responsible for the metabolism of chlorpromazine. Decreased metabolism of chlorpromazine may lead to clinically important adverse reactions such as QT prolongation or TdP. Serum concentrations of thioridazine, a phenothiazine that is also highly dependent on CYP2D6 for its metabolism, increased three-fold during coadministration with fluvoxamine.
Food: (Major) Advise patients to avoid cannabis use while taking CNS depressants due to the risk for additive CNS depression and potential for other cognitive adverse reactions.
Foscarnet: (Major) When possible, avoid concurrent use of foscarnet with other drugs known to prolong the QT interval, such as chlorpromazine. Foscarnet has been associated with postmarketing reports of both QT prolongation and torsade de pointes (TdP). Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and TdP. If these drugs are administered together, obtain an electrocardiogram and electrolyte concentrations before and periodically during treatment.
Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Fosphenytoin: (Moderate) Monitor phenytoin concentrations during concomitant therapy with fosphenytoin and phenothiazines; a fosphenytoin dosage decrease may be necessary. Phenothiazines may inhibit the metabolism of fosphenytoin.
Fostemsavir: (Major) Use chlorpromazine and fostemsavir together with caution. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Supratherapeutic doses of fostemsavir (2,400 mg twice daily, four times the recommended daily dose) have been shown to cause QT prolongation. Fostemsavir causes dose-dependent QT prolongation.
Gabapentin: (Major) Initiate gabapentin at the lowest recommended dose and monitor patients for symptoms of sedation and somnolence during coadministration of gabapentin and chlorpromazine. Concomitant use of gabapentin with chlorpromazine may cause additive CNS depression. Educate patients about the risks and symptoms of excessive CNS depression.
Galantamine: (Moderate) Conventional antipsychotics with significant anticholinergic effects, such as chlorpromazine, are more likely than other conventional antipsychotics to diminish the therapeutic action of galantamine, and use of an alternative antipsychotic should be considered. Galantamine inhibits acetylcholinesterase, the enzyme responsible for the degradation of acetylcholine, and exerts its therapeutic effect by improving the availability of acetylcholine. Consider the use of an antipsychotic with less prominent anticholinergic effects.
Ganirelix: (Moderate) In the absence of relevant data and as a precaution, drugs that cause hyperprolactinemia, such as phenothiazines, should not be administered concomitantly with ganirelix since hyperprolactinemia downregulates the number of pituitary GnRH receptors.
Gemifloxacin: (Major) Concurrent use of chlorpromazine and gemifloxacin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Chlorpromazine is associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Gemifloxacin may also prolong the QT interval in some patients, with the maximal change in the QTc interval occurring approximately 5 to 10 hours following oral administration. The likelihood of QTc prolongation may increase with increasing dose of gemifloxacin; therefore, the recommended dose should not be exceeded especially in patients with renal or hepatic impairment where the Cmax and AUC are slightly higher.
Gemtuzumab Ozogamicin: (Major) Use gemtuzumab ozogamicin and chlorpromazine together with caution due to the potential for additive QT interval prolongation and risk of torsade de pointes (TdP). If these agents are used together, obtain an ECG and serum electrolytes prior to the start of gemtuzumab and as needed during treatment. Although QT interval prolongation has not been reported with gemtuzumab ozogamicin, it has been reported with other drugs that contain calicheamicin. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Gentamicin: (Minor) When used for the treatment of nausea and vomiting, antiemetic phenothiazines may effectively mask symptoms that are associated with ototoxicity induced by the aminoglycosides.
Gilteritinib: (Major) Use caution and monitor for evidence of QT prolongation if concurrent use of gilteritinib and chlorpromazine is necessary. Gilteritinib has been associated with QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Glasdegib: (Major) Avoid coadministration of glasdegib with chlorpromazine due to the potential for additive QT prolongation. If coadministration cannot be avoided, monitor patients for increased risk of QT prolongation with increased frequency of ECG monitoring. Glasdegib therapy may result in QT prolongation and ventricular arrhythmias including ventricular fibrillation and ventricular tachycardia. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Glimepiride: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure.
Glipizide: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure.
Glipizide; Metformin: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure. (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.
Glyburide: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure.
Glyburide; Metformin: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure. (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.
Glycopyrrolate: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Glycopyrrolate; Formoterol: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Goserelin: (Major) Avoid coadministration of goserelin with chlorpromazine due to the risk of reduced efficacy of goserelin; QT prolongation may also occur. Chlorpromazine can cause hyperprolactinemia, which reduces the number of pituitary gonadotropin releasing hormone (GnRH) receptors; goserelin is a GnRH analog. Additionally, chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Androgen deprivation therapy (i.e., goserelin) may also prolong the QT/QTc interval.
Granisetron: (Major) Due to a possible risk for QT prolongation and torsade de pointes (TdP), granisetron and chlorpromazine should be used together cautiously. Granisetron has been associated with QT prolongation. According to the manufacturer, use of granisetron with drugs known to prolong the QT interval or are arrhythmogenic, may result in clinical consequences. Phenothiazines have been associated with a risk of QT prolongation or TdP. This risk is generally higher at elevated concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use.
Guaifenesin; Hydrocodone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Guaifenesin; Phenylephrine: (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Guanidine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Halobetasol; Tazarotene: (Moderate) The manufacturer states that tazarotene should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as phenothiazines, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
Halogenated Anesthetics: (Major) Halogenated anesthetics should be used cautiously and with close monitoring with chlorpromazine. Halogenated anesthetics can prolong the QT interval. Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. In addition, phenothiazines can potentiate the CNS-depressant action of anesthetics.
Haloperidol: (Major) Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Other antipsychotics associated with a possible risk for QT prolongation and TdP which should be avoided during treatment with chlorpromazine include haloperidol. Coadministration may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Histrelin: (Major) Avoid coadministration of histrelin with chlorpromazine due to the risk of reduced efficacy of histrelin; QT prolongation may also occur. Chlorpromazine can cause hyperprolactinemia, which reduces the number of pituitary gonadotropin releasing hormone (GnRH) receptors; histrelin is a GnRH analog. Additionally, chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Androgen deprivation therapy (i.e., histrelin) may also prolong the QT/QTc interval.
Homatropine; Hydrocodone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Hydrocodone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Hydrocodone; Ibuprofen: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Hydrocodone; Pseudoephedrine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Avoid prescribing opioid cough medications in patients taking chlorpromazine. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Hydromorphone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Hydroxychloroquine: (Major) Concomitant use of hydroxychloroquine and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Hydroxyzine: (Major) Concomitant use of hydroxyzine and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Hyoscyamine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Ibuprofen; Oxycodone: (Major) Concomitant use of oxycodone with phenothiazines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medication with phenothiazines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Monitor for signs of hypotension after starting or titrating the dosage of oxycodone. There is an increased risk of severe hypotension in patients whose ability to maintain blood pressure has already been compromised by concurrent administration of phenothiazines.
Ibutilide: (Major) Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. Ibutilide administration can cause QT prolongation and torsades de pointes (TdP); proarrhythmic events should be anticipated. The potential for proarrhythmic events with ibutilide increases with the coadministration of other drugs that prolong the QT interval.
Iloperidone: (Major) Iloperidone has been associated with QT prolongation; however, torsade de pointes (TdP) has not been reported. According to the manufacturer, since iloperidone may prolong the QT interval, it should be avoided in combination with other agents also known to have this effect, such as chlorpromazine. In addition, coadministration may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Imipramine: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Incretin Mimetics: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Indacaterol; Glycopyrrolate: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Indapamide: (Moderate) Indapamide may cause electrolyte disturbances, which may increase the potential for proarrhythmic effects of selected phenothiazines.
Inotuzumab Ozogamicin: (Major) Avoid coadministration of inotuzumab ozogamicin with chlorpromazine due to the potential for additive QT interval prolongation and risk of torsade de pointes (TdP). If coadministration is unavoidable, obtain an ECG and serum electrolytes prior to the start of treatment, after treatment initiation, and periodically during treatment. Inotuzumab has been associated with QT interval prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Insulins: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Iodixanol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Iohexol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Iomeprol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Iopamidol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Iopromide: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Ioversol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Ipecac: (Major) Phenothiazines, especially in large quantities, can cause a dystonic reaction. Due to the aspiration risk associated with emesis for a person with acute dystonia of the head or neck,avoid emesis induction for overdose cases. Therefore ipecac use in the setting of phenothiazine overdose is not recommended.
Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Isocarboxazid: (Moderate) Due to the potential for additive CNS and cardiovascular effects, MAOIs and phenothiazines should be used together cautiously. Concurrent use of MAOIs and phenothiazines may prolong or intensify the hypotensive, anticholinergic, or sedative effects of either agent.
Isoflurane: (Major) Halogenated anesthetics should be used cautiously and with close monitoring with chlorpromazine. Halogenated anesthetics can prolong the QT interval. Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. In addition, phenothiazines can potentiate the CNS-depressant action of anesthetics.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Isoniazid, INH; Rifampin: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Isosulfan Blue: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Itraconazole: (Major) Itraconazole has been associated with prolongation of the QT interval. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with itraconazole include chlorpromazine.
Ivosidenib: (Major) Avoid coadministration of ivosidenib with chlorpromazine due to an increased risk of QT prolongation. If concomitant use is unavoidable, monitor ECGs for QTc prolongation and monitor electrolytes; correct any electrolyte abnormalities as clinically appropriate. An interruption of therapy and dose reduction of ivosidenib may be necessary if QT prolongation occurs. Prolongation of the QTc interval and ventricular arrhythmias have been reported in patients treated with ivosidenib. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Ketamine: (Moderate) Phenothiazines can potentiate the CNS-depressant action of other drugs such as general anesthetics. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension.
Ketoconazole: (Contraindicated) Avoid concomitant use of ketoconazole and chlorpromazine due to an increased risk for torsade de pointes (TdP) and QT/QTc prolongation.
Lansoprazole; Amoxicillin; Clarithromycin: (Major) Concurrent use of chlorpromazine and clarithromycin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Both clarithromycin and chlorpromazine are specifically associated with an established risk of QT prolongation and TdP.
Lapatinib: (Major) Monitor ECGs for QT prolongation and monitor electrolytes if coadministration of lapatinib with chlorpromazine is necessary; correct electrolyte abnormalities prior to treatment. Lapatinib has been associated with concentration-dependent QT prolongation; ventricular arrhythmias and torsade de pointes (TdP) have been reported in postmarketing experience with lapatinib. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Lasmiditan: (Moderate) Monitor for excessive sedation and somnolence during coadministration of lasmiditan and chlorpromazine. Concurrent use may result in additive CNS depression.
Lefamulin: (Major) Avoid coadministration of lefamulin with chlorpromazine as concurrent use may increase the risk of QT prolongation. If coadministration cannot be avoided, ECG monitoring is recommended during treatment. Lefamulin has a concentration dependent QTc prolongation effect. The pharmacodynamic interaction potential to prolong the QT interval of the electrocardiogram between lefamulin and other drugs that effect cardiac conduction is unknown. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Lemborexant: (Moderate) Monitor for excessive sedation and somnolence during coadministration of lemborexant and phenothiazines. Dosage adjustments of lemborexant and the phenothiazine may be necessary when administered together because of potentially additive CNS effects. The risk of next-day impairment, including impaired driving, is increased if lemborexant is taken with other CNS depressants.
Lenvatinib: (Major) Avoid coadministration of lenvatinib with chlorpromazine due to the risk of QT prolongation. Prolongation of the QT interval has been reported with lenvatinib therapy. Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and torsade de pointes (TdP).
Leuprolide: (Major) Avoid coadministration of leuprolide with chlorpromazine due to the risk of reduced efficacy of leuprolide; QT prolongation may also occur. Chlorpromazine can cause hyperprolactinemia, which reduces the number of pituitary gonadotropin releasing hormone (GnRH) receptors; leuprolide is a GnRH analog. Additionally, chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Androgen deprivation therapy (i.e., leuprolide) may also prolong the QT/QTc interval.
Leuprolide; Norethindrone: (Major) Avoid coadministration of leuprolide with chlorpromazine due to the risk of reduced efficacy of leuprolide; QT prolongation may also occur. Chlorpromazine can cause hyperprolactinemia, which reduces the number of pituitary gonadotropin releasing hormone (GnRH) receptors; leuprolide is a GnRH analog. Additionally, chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Androgen deprivation therapy (i.e., leuprolide) may also prolong the QT/QTc interval.
Levodopa: (Major) Avoid concurrent use if possible and consider an atypical antipsychotic as an alternative to the phenothiazine. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors. Due to opposing effects on central dopaminergic activity, phenothiazines and levodopa may interfere with the effectiveness of each other.
Levofloxacin: (Major) Concomitant use of levofloxacin and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Levoketoconazole: (Contraindicated) Avoid concomitant use of ketoconazole and chlorpromazine due to an increased risk for torsade de pointes (TdP) and QT/QTc prolongation.
Levonorgestrel; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Levorphanol: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Reduce the initial dose of levorphanol by approximately 50% or more. Educate patients about the risks and symptoms of excessive CNS depression.
Lidocaine; Epinephrine: (Moderate) Monitor blood pressure during concomitant epinephrine and phenothiazine use. Phenothiazines antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by a phenothiazine, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Linagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Linagliptin; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. (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.
Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Lithium: (Major) Some atypical antipsychotics are considered first-line adjunctive therapy to mood stabilizers such as lithium. Because both chlorpromazine and lithium have been associated with QT prolongation, coadminister cautiously and with close monitoring. It is also advisable to monitor patients for neurotoxicity during co-administration. Neuroleptic malignant syndrome (NMS) has been observed occasionally during concurrent use of lithium and either atypical or conventional antipsychotics. Additive extrapyramidal effects have also been noted. Early case reports described an encephalopathic syndrome consisting of delirium, tremulousness, dyskinesia, seizures, leukocytosis, weakness, hyperpyrexia, confusion, extrapyramidal symptoms, elevations in laboratory values (e.g., liver function tests, blood urea nitrogen, fasting blood sugar) and, in some cases, irreversible brain damage, during use of lithium and conventional antipsychotics, particularly haloperidol. Subsequent rare reports of NMS or NMS-like reactions have been described during co-administration of lithium and atypical antipsychotics (e.g., aripiprazole, risperidone, olanzapine, clozapine). Following resolution of NMS, there are isolated instances of re-emergence of symptoms following re-initiation of lithium as monotherapy. Lithium may be a risk factor for antipsychotic-induced NMS; however, this hypothesis has not been confirmed. In many reported cases, confounding factors have been present (e.g., previous history of NMS, high dose therapy). The ability of antipsychotics alone to precipitate NMS and the rarity of the condition further complicate assessment of lithium as a risk factor.
Lofexidine: (Major) Monitor the ECG for QT prolongation and monitor for additive orthostatic hypotension and sedation during concurrent use of lofexidine and chlorpromazine. Lofexidine prolongs the QT interval and torsade de pointes (TdP) has been reported during postmarketing use. Chlorpromazine is associated with an established risk of QT prolongation and TdP. Both agents can cause orthostasis and sedation, which may be additive during coadministration.
Loperamide: (Major) Concomitant use of loperamide and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Loperamide; Simethicone: (Major) Concomitant use of loperamide and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Lopinavir; Ritonavir: (Major) Avoid coadministration of lopinavir with chlorpromazine due to the potential for additive QT prolongation. If use together is necessary, obtain a baseline ECG to assess initial QT interval and determine frequency of subsequent ECG monitoring, avoid any non-essential QT prolonging drugs, and correct electrolyte imbalances. Lopinavir is associated with QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Lorazepam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Loxapine: (Moderate) Caution is advisable during concurrent use of antipsychotics, including loxapine and chlorpromazine. Coadministration may increase the risk for drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, and seizures.
Lumateperone: (Moderate) Coadministration of antipsychotics, such as lumateperone and chlorpromazine, may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. Although the incidence of tardive dyskinesia from antipsychotic combinations has not been established and data are very limited, the risk may be increased during combined use versus use of an antipsychotic alone.
Lurasidone: (Major) Lurasidone administration has been associated with drowsiness, dizziness, orthostatic hypotension, extrapyramidal symptoms, neuroleptic malignant syndrome, and seizures. The risk of these adverse effects may be increased during concurrent use of lurasidone with other antipsychotics. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Macimorelin: (Major) Avoid concurrent administration of macimorelin with drugs that prolong the QT interval, such as chlorpromazine. Use of these drugs together may increase the risk of developing torsade de pointes-type ventricular tachycardia. Sufficient washout time of drugs that are known to prolong the QT interval prior to administration of macimorelin is recommended. Treatment with macimorelin has been associated with an increase in the corrected QT (QTc) interval. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Magnesium Hydroxide: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
Magnesium Sulfate; Potassium Sulfate; Sodium Sulfate: (Major) Administer chlorpromazine at least 2 hours before or 6 hours after administration of magnesium sulfate; potassium sulfate; sodium sulfate. The absorption of chlorpromazine may be reduced by chelation with magnesium sulfate.
Maprotiline: (Major) Phenothiazines have been reported to prolong the QT interval. Because maprotiline is associated with a possible risk for QT prolongation and torsade de pointes (TdP), concurrent use with chlorpromazine should be approached with caution. If coadministration is considered necessary, and the patient has known risk factors for cardiac disease or arrhythmia, then close monitoring is essential. In addition, additive anticholinergic effects may be seen when phenothiazines are used concomitantly with other drugs with antimuscarinic activity such as maprotiline. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive hypotension or CNS effects such as drowsiness may also occur.
Meclizine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with meclizine. Patients should be informed to read non-prescription product labels carefully for additional interacting motion sickness medications.
Mefloquine: (Major) Concurrent use of chlorpromazine and mefloquine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Chlorpromazine is associated with QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. There is also evidence that the use of halofantrine after mefloquine causes a significant lengthening of the QTc interval. However, use of mefloquine alone has not been reported to cause QT prolongation.
Meglitinides: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Melatonin: (Moderate) Monitor for unusual drowsiness and excessive duration during coadministration of melatonin and phenothiazines due to the risk for additive CNS depression.
Meperidine: (Major) Additive CNS depression or hypotensive effects are possible during concurrent use of phenothiazines and meperidine. In addition, an increased risk of seizures is possible due to phenothiazine-induced decreases in the seizure threshold, particularly during routine use. If meperidine is used with a phenothiazine, the meperidine dosage is recommended to be reduced by 25% to 50%. Further dose adjustments may be needed.
Meprobamate: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered with other CNS depressant drugs and they should be used cautiously with anxiolytic, sedative, and hypnotics. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of hypnotics and other CNS depressants than with use of a hypnotic alone.
Metaxalone: (Moderate) Phenothiazines can potentiate the CNS-depressant action of skeletal muscle relaxants like metaxalone. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects.
Metformin: (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.
Metformin; Repaglinide: (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.
Metformin; Rosiglitazone: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. (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.
Metformin; Saxagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. (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.
Metformin; Sitagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. (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.
Methadone: (Major) The need to coadminister methadone with drugs known to prolong the QT interval should be done with extreme caution and a careful assessment of treatment risks versus benefits. Methadone is associated with an increased risk for QT prolongation and torsade de pointes (TdP), especially at higher doses (> 200 mg/day but averaging approximately 400 mg/day in adult patients). In addition, methadone is a substrate for CYP3A4, CYP2D6, and P-glycoprotein (P-gp). Concurrent use of methadone with inhibitors of these enzymes may result in increased serum concentrations of methadone. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP and inhibits CYP2D6. In addition, concomitant use of methadone with another CNS depressant, such as chlorpromazine, can also lead to additive respiratory depression, hypotension, profound sedation, or coma. Prior to use of methadone in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. Methadone should be used with caution and in reduced dosages if used concurrently with a CNS depressant; also consider a using a lower dose of the CNS depressant. Monitor patients for sedation and respiratory depression.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Methocarbamol: (Moderate) Monitor for unusual drowsiness and sedation during coadministration of methocarbamol and phenothiazines due to the risk for additive CNS depression; dosage adjustments may be necessary.
Methohexital: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Methoxsalen: (Moderate) Use methoxsalen and phenothiazines together with caution; the risk of severe burns/photosensitivity may be additive. If concurrent use is necessary, closely monitor patients for signs or symptoms of skin toxicity.
Methscopolamine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Methsuximide: (Major) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Methyclothiazide: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Metoclopramide: (Contraindicated) Avoid metoclopramide in patients receiving phenothiazine antipsychotics due to potential for additive effects, including increased frequency and severity of tardive dyskinesia (TD), other extrapyramidal symptoms (EPS), and neuroleptic malignant syndrome (NMS). Also avoid the use of metoclopramide with phenothiazine antiemetics if possible due to these risks. Some manufacturer labels for metoclopramide contraindicate the use of these drugs together, while others state avoidance is necessary. If these agents must be used together, monitor closely for movement disorders and additive CNS effects. Discontinue these medications at the first signs of dyskinesia. Metoclopramide is a central dopamine antagonist and may cause EPS (e.g., acute dystonic reactions, pseudo-parkinsonism, akathisia, tardive dyskinesia). Tardive dyskinesia (TD) is a syndrome of potentially irreversible and disfiguring involuntary movements of the face or tongue, and sometimes of the trunk and/or extremities. Movements may be choreoathetotic in appearance. Phenothiazines are also central dopamine antagonists. In addition, both phenothiazines and metoclopramide can cause sedation, seizures, or increased prolactin levels.
Metolazone: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Metoprolol: (Moderate) Monitor for metoprolol-related adverse reactions, including bradycardia and hypotension, during coadministration with chlorpromazine. Concomitant use may increase metoprolol serum concentrations which would decrease the cardioselectivity of metoprolol. Metoprolol is a CYP2D6 substrate and chlorpromazine is a CYP2D6 inhibitor.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines. (Moderate) Monitor for metoprolol-related adverse reactions, including bradycardia and hypotension, during coadministration with chlorpromazine. Concomitant use may increase metoprolol serum concentrations which would decrease the cardioselectivity of metoprolol. Metoprolol is a CYP2D6 substrate and chlorpromazine is a CYP2D6 inhibitor.
Metronidazole: (Major) Concomitant use of metronidazole and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Metyrapone: (Moderate) Metyrapone may cause dizziness and/or drowsiness. Other drugs that may also cause drowsiness, such as phenothiazines, should be used with caution. Additive drowsiness and/or dizziness is possible.
Metyrosine: (Moderate) Because it also blocks central dopamine receptors, metyrosine should be avoided or used cautiously in patients receiving a phenothiazine to minimize the risk of additive adverse CNS effects. A dose reduction may be required if combination therapy is necessary.
Mexiletine: (Moderate) Mexiletine is significantly metabolized by CYP2D6 isoenzymes. CYP2D6 inhibitors, such as chlorpromazine, could theoretically impair mexiletine metabolism; the clinical significance of such interactions is unknown.
Midazolam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Midostaurin: (Major) The concomitant use of midostaurin and chlorpromazine may lead to additive QT interval prolongation. If these drugs are used together, consider obtaining electrocardiograms to monitor the QT interval. In clinical trials, QT prolongation was reported in patients who received midostaurin as single-agent therapy or in combination with cytarabine and daunorubicin. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). The risk of QT prolongation and TdP is generally higher at elevated concentrations of phenothiazines. However, case reports have included patients receiving therapeutic doses of chlorpromazine.
Miglitol: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Minocycline: (Minor) Injectable minocycline contains magnesium sulfate heptahydrate. Because of the CNS-depressant effects of magnesium sulfate, additive central-depressant effects can occur following concurrent administration with CNS depressants such as phenothiazines. Caution should be exercised when using these agents concurrently.
Mirabegron: (Moderate) Mirabegron is a moderate CYP2D6 inhibitor. Exposure of drugs metabolized by CYP2D6 isoenzymes such as chlorpromazine may be increased when co-administered with mirabegron. Chlorpromazine is primarily metabolized by CYP2D6. Therefore, appropriate monitoring and dose adjustment may be necessary.
Mirtazapine: (Major) Coadministration may increase the risk of QT prolongation, torsade de pointes, and CNS depression. Due to the possibility of additive effects on the QT interval, caution is advisable during concurrent use of chlorpromazine and mirtazapine. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Cases of QT prolongation, TdP, ventricular tachycardia, and sudden death have been reported during postmarketing use of mirtazapine. The majority of reports have occurred in the setting of mirtazapine overdose or in patients with other risk factors for QT prolongation, including concomitant use of other medications associated with QT prolongation. Both drugs also have CNS depressant properties, and patients should be advised to avoid engaging in activities requiring mental alertness until they are aware of the effects of the combination.
Mitotane: (Moderate) Mitotane can cause sedation, lethargy, vertigo, and other CNS side effects. Concomitant administration of mitotane and CNS depressants, including opiate agonists, may cause additive CNS effects.
Mobocertinib: (Major) Concomitant use of mobocertinib and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Molindone: (Major) Close monitoring is advisable during concurrent use of molindone with other antipsychotics. Because molindone shares certain pharmacological properties with other antipsychotics, additive cardiac effects (e.g., hypotension), CNS effects (e.g., drowsiness), anticholinergic effects (e.g., constipation, xerostomia), extrapyramidal effects, neuroleptic malignant syndrome, or seizures may occur. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Monoamine oxidase inhibitors: (Moderate) Due to the potential for additive CNS and cardiovascular effects, MAOIs and phenothiazines should be used together cautiously. Concurrent use of MAOIs and phenothiazines may prolong or intensify the hypotensive, anticholinergic, or sedative effects of either agent.
Morphine: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. For extended-release morphine tablets, start with 15 mg every 12 hours. Morphine; naltrexone should be initiated at 1/3 to 1/2 the recommended starting dosage. Educate patients about the risks and symptoms of excessive CNS depression.
Morphine; Naltrexone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. For extended-release morphine tablets, start with 15 mg every 12 hours. Morphine; naltrexone should be initiated at 1/3 to 1/2 the recommended starting dosage. Educate patients about the risks and symptoms of excessive CNS depression.
Moxifloxacin: (Major) Concurrent use of chlorpromazine and moxifloxacin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Moxifloxacin has been associated with prolongation of the QT interval. Additionally, post-marketing surveillance has identified very rare cases of ventricular arrhythmias including TdP, usually in patients with severe underlying proarrhythmic conditions. The likelihood of QT prolongation may increase with increasing concentrations of moxifloxacin, therefore the recommended dose or infusion rate should not be exceeded. Phenothiazines have also been associated with a risk of QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Nabilone: (Moderate) Concomitant use of nabilone with other CNS depressants, including phenothiazines, can potentiate the effects of nabilone on respiratory depression.
Nafarelin: (Moderate) Antipsychotics may cause hyperprolactinemia and should not be administered concomitantly with nafarelin since hyperprolactinemia down-regulates the number of pituitary GnRH receptors.
Nalbuphine: (Moderate) Concomitant use of nalbuphine with other CNS depressants, such as phenothiazines, can potentiate the effects of nalbuphine on respiratory depression, CNS depression, and sedation.
Naltrexone: (Moderate) Patients receiving phenothiazines and naltrexone concomitantly have had symptoms of somnolence and lethargy.
Nebivolol: (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with chlorpromazine; adjust the nebivolol dose according to blood pressure response. Concomitant use may increase the exposure of nebivolol. Nebivolol is a CYP2D6 substrate and chlorpromazine is a moderate CYP2D6 inhibitor.
Nebivolol; Valsartan: (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with chlorpromazine; adjust the nebivolol dose according to blood pressure response. Concomitant use may increase the exposure of nebivolol. Nebivolol is a CYP2D6 substrate and chlorpromazine is a moderate CYP2D6 inhibitor.
Neostigmine; Glycopyrrolate: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Nilotinib: (Major) Avoid the concomitant use of nilotinib and chlorpromazine; significant prolongation of the QT interval may occur. Sudden death and QT prolongation have been reported in patients who received nilotinib therapy. Chlorpromazine is associated with an established risk of QT prolongation and torsade de pointes.
Nitroglycerin: (Minor) Nitroglycerin can cause hypotension. This action may be additive with other agents that can cause hypotension such as phenothiazines. Patients should be monitored more closely for hypotension if nitroglycerin is used concurrently with phenothiazines.
Non-Ionic Contrast Media: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering the use of intrathecal radiopaque contrast agents. Phenothiazines should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
Norepinephrine: (Minor) The alpha-adrenergic effects of norepinephrine can be blocked during concurrent administration of phenothiazines. This blockade can lead to severe hypotension, tachycardia, and, potentially, myocardial infarction. Patients taking phenothiazines can possibly have reduced pressor response to ephedrine, phenylephrine, or norepinephrine, but these drugs are preferred over epinephrine if a vasopressor agent is required. According to the manufacturers of the various phenothiazines, norepinephrine or phenylephrine may be used if a vasopressor is needed.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Norethindrone; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Norgestimate; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Nortriptyline: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Ofloxacin: (Major) Concomitant use of ofloxacin and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Olanzapine: (Major) Concurrent use of olanzapine and chlorpromazine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Limited data, including some case reports, suggest that olanzapine may also be associated with a significant prolongation of the QTc interval in rare instances. In addition, coadministration may increase the risk of drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, or seizures. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Olanzapine; Fluoxetine: (Major) Concurrent use of olanzapine and chlorpromazine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Limited data, including some case reports, suggest that olanzapine may also be associated with a significant prolongation of the QTc interval in rare instances. In addition, coadministration may increase the risk of drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, or seizures. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone. (Major) Fluoxetine is associated with a possible risk of QT prolongation and torsade de pointes (TdP) and chlorpromazine also has an established risk of QT prolongation and TdP. Combination therapy with these agents should be avoided if possible. Fluoxetine is a potent inhibitor of CYP2D6 and may result in increases in serum phenothiazine concentrations, which may lead to phenothiazine-related side effects such as cardiac side effects, hypotension, CNS sedation, or extrapyramidal symptoms. The effects of fluoxetine on hepatic metabolism of interacting drugs may persist for a time after discontinuation of fluoxetine because of its long elimination half-life.
Olanzapine; Samidorphan: (Major) Concurrent use of olanzapine and chlorpromazine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Limited data, including some case reports, suggest that olanzapine may also be associated with a significant prolongation of the QTc interval in rare instances. In addition, coadministration may increase the risk of drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, or seizures. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Oliceridine: (Moderate) Monitor patients closely for respiratory depression and sedation at frequent intervals and base subsequent doses on the patient's severity of pain and response to treatment if concomitant administration of oliceridine and chlorpromazine is necessary; less frequent dosing of oliceridine may be required. Concomitant use of oliceridine and chlorpromazine may increase the plasma concentration of oliceridine, resulting in increased or prolonged opioid effects. If chlorpromazine is discontinued, consider increasing the oliceridine dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oliceridine is a CYP2D6 substrate and chlorpromazine is a moderate CYP2D6 inhibitor.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Omeprazole; Amoxicillin; Rifabutin: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Ondansetron: (Major) Concomitant use of ondansetron and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary. Do not exceed 16 mg of IV ondansetron in a single dose; the degree of QT prolongation associated with ondansetron significantly increases above this dose.
Oritavancin: (Moderate) Chlorpromazine is metabolized by CYP2D6; oritavancin is a weak CYP2D6 inducer. Plasma concentrations and efficacy of chlorpromazine may be reduced if these drugs are administered concurrently.
Orphenadrine: (Moderate) Additive anticholinergic effects may be seen when chlorpromazine is used concomitantly with other drugs having antimuscarinic activity such as orphenadrine. Additive sedation may also occur.
Osilodrostat: (Major) Monitor ECGs in patients receiving osilodrostat with chlorpromazine. Osilodrostat is associated with dose-dependent QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes.
Osimertinib: (Major) Avoid coadministration of chlorpromazine with osimertinib if possible due to the risk of QT prolongation and torsade de pointes (TdP). If concomitant use is unavoidable, periodically monitor ECGs for QT prolongation and monitor electrolytes; an interruption of osimertinib therapy with dose reduction or discontinuation of therapy may be necessary if QT prolongation occurs. Concentration-dependent QTc prolongation occurred during clinical trials of osimertinib. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Oxaliplatin: (Major) Monitor ECGs and electrolytes in patients receiving oxaliplatin and chlorpromazine concomitantly; correct electrolyte abnormalities prior to administration of oxaliplatin. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). QT prolongation and ventricular arrhythmias including fatal torsade de pointes have been reported with oxaliplatin use in postmarketing experience.
Oxazepam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Oxybutynin: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Oxycodone: (Major) Concomitant use of oxycodone with phenothiazines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medication with phenothiazines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Monitor for signs of hypotension after starting or titrating the dosage of oxycodone. There is an increased risk of severe hypotension in patients whose ability to maintain blood pressure has already been compromised by concurrent administration of phenothiazines.
Oxymorphone: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Reduce the initial oxymorphone dosage by 1/3 to 1/2. Educate patients about the risks and symptoms of excessive CNS depression.
Ozanimod: (Major) In general, do not initiate ozanimod in patients taking chlorpromazine due to the risk of additive bradycardia, QT prolongation, and torsade de pointes (TdP). If treatment initiation is considered, seek advice from a cardiologist. Ozanimod initiation may result in a transient decrease in heart rate and atrioventricular conduction delays. Ozanimod has not been studied in patients taking concurrent QT prolonging drugs; however, QT prolonging drugs have been associated with TdP in patients with bradycardia. Chlorpromazine is associated with an established risk of QT prolongation and TdP.
Pacritinib: (Major) Concomitant use of pacritinib and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Paliperidone: (Major) Paliperidone has been associated with QT prolongation; torsade de pointes (TdP) and ventricular fibrillation have been reported in the setting of overdose. According to the manufacturer, since paliperidone may prolong the QT interval, it should be avoided in combination with other agents also known to have this effect, such as chlorpromazine. However, if coadministration is considered necessary and the patient has known risk factors for cardiac disease or arrhythmias, close monitoring is essential. In addition, the risk of drowsiness, dizziness, hypotension, extrapyramidal symptoms, anticholinergic effects, neuroleptic malignant syndrome, or seizures may be increased during combined use of antipsychotics; therefore, it may be advisable to initiate treatment with lower dosages if combination therapy is necessary. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Panobinostat: (Major) QT prolongation has been reported with panobinostat therapy in patients with multiple myeloma in a clinical trial; use of panobinostat with other agents that prolong the QT interval is not recommended. Obtain an electrocardiogram at baseline and periodically during treatment. Hold panobinostat if the QTcF increases to >= 480 milliseconds during therapy; permanently discontinue if QT prolongation does not resolve. Drugs with a possible risk for QT prolongation and torsade de pointes that should be used cautiously and with close monitoring with panobinostat include chlorpromazine.
Paromomycin: (Minor) When used for the treatment of nausea and vomiting, antiemetic phenothiazines may effectively mask symptoms that are associated with ototoxicity induced by the aminoglycosides.
Paroxetine: (Moderate) Monitor for an increase in chlorpromazine- and paroxetine-related adverse reactions, including QT prolongation, anticholinergic effects, orthostasis, somnolence, and serotonin syndrome, if coadministration is necessary. Concomitant use may increase the exposure of both drugs. Both chlorpromazine and paroxetine are CYP2D6 substrates; paroxetine is a strong CYP2D6 inhibitor and chlorpromazine is a moderate CYP2D6 inhibitor.
Pasireotide: (Major) Cautious use of pasireotide and chlorpromazine is needed, as coadministration may have additive effects on the prolongation of the QT interval. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Pazopanib: (Major) Coadministration of pazopanib and other drugs that prolong the QT interval (e.g., chlorpromazine) is not advised; pazopanib has been reported to prolong the QT interval. If pazopanib and chlorpromazine must be continued, closely monitor the patient for QT interval prolongation.
Peginterferon Alfa-2b: (Moderate) Monitor for adverse effects associated with increased exposure to chlorpromazine if peginterferon alfa-2b is coadministered. Peginterferon alfa-2b is a CYP2D6 inhibitor, while chlorpromazine is a CYP2D6 substrate.
Pentamidine: (Major) Phenothiazines may cause QT prolongation. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and torsade de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. Drugs with a possible risk for QT prolongation and TdP that should be used with caution with chlorpromazine include pentamidine. Pentamidine has been associated with QT prolongation.
Pentazocine: (Moderate) Concomitant use of pentazocine with other CNS depressants, such as phenothiazines, can potentiate respiratory depression, CNS depression, and sedation. Pentazocine should be used cautiously with phenothiazines.
Pentazocine; Naloxone: (Moderate) Concomitant use of pentazocine with other CNS depressants, such as phenothiazines, can potentiate respiratory depression, CNS depression, and sedation. Pentazocine should be used cautiously with phenothiazines.
Pentobarbital: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Perampanel: (Moderate) Co-administration of perampanel with CNS depressants, including ethanol, may increase CNS depression. The combination of perampanel (particularly at high doses) with ethanol has led to decreased mental alertness and ability to perform complex tasks (such as driving), as well as increased levels of anger, confusion, and depression; similar reactions should be expected with concomitant use of other CNS depressants, such as phenothiazines.
Perphenazine: (Moderate) Coadministration of chlorpromazine and perphenazine should be avoided when possible. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Perphenazine is also a phenothiazine and is associated with a possible risk for QT prolongation. In addition, coadministration may increase the risk of drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, or seizures.
Perphenazine; Amitriptyline: (Moderate) Coadministration of chlorpromazine and perphenazine should be avoided when possible. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Perphenazine is also a phenothiazine and is associated with a possible risk for QT prolongation. In addition, coadministration may increase the risk of drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, or seizures. (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Pexidartinib: (Moderate) Monitor for evidence of hepatotoxicity if pexidartinib is coadministered with chlorpromazine. Avoid concurrent use in patients with increased serum transaminases, total bilirubin, or direct bilirubin (more than ULN) or active liver or biliary tract disease.
Phenelzine: (Moderate) Due to the potential for additive CNS and cardiovascular effects, MAOIs and phenothiazines should be used together cautiously. Concurrent use of MAOIs and phenothiazines may prolong or intensify the hypotensive, anticholinergic, or sedative effects of either agent.
Phenobarbital: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur. (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Phentermine; Topiramate: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Phenylephrine: (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Phenytoin: (Moderate) Monitor phenytoin concentrations during concomitant therapy with phenytoin and phenothiazines; a phenytoin dosage decrease may be necessary. Phenothiazines may inhibit the metabolism of phenytoin.
Photosensitizing agents (topical): (Moderate) Phenothiazines may increase the photosensitizing effects of photosensitizing agents used in photodynamic therapy. Patients should limit ultra-violet exposure.
Pilocarpine: (Moderate) Avoid using pilocarpine in combination with other drugs known to have anticholinergic effects as the therapeutic efficacy of either agent may be reduced.
Pimavanserin: (Major) Pimavanserin may cause QT prolongation and should generally be avoided in patients receiving other medications known to prolong the QT interval, such as chlorpromazine. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Coadministration may increase the risk for QT prolongation.
Pimozide: (Contraindicated) Pimozide is associated with a well-established risk of QT prolongation and torsade de pointes (TdP). Due to the risk of additive QT prolongation and potential for serious arrhythmias, the concurrent use of pimozide with chlorpromazine is contraindicated. Concurrent use of pimozide with phenothiazines may increase the risk of adverse effects such as drowsiness, sedation, dizziness, orthostatic hypotension, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone. Many phenothiazines are inhibitors of CYP2D6, one of the metabolic pathways of pimozide.
Pioglitazone: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Pioglitazone; Glimepiride: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure. (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Pioglitazone; Metformin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. (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.
Pitolisant: (Major) Avoid coadministration of pitolisant with chlorpromazine as concurrent use may increase the risk of QT prolongation. Pitolisant prolongs the QT interval. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Plazomicin: (Minor) When used for the treatment of nausea and vomiting, antiemetic phenothiazines may effectively mask symptoms that are associated with ototoxicity induced by the aminoglycosides.
Polyethylene Glycol; Electrolytes: (Major) Administer chlorpromazine at least 2 hours before or 6 hours after administration of magnesium sulfate; potassium sulfate; sodium sulfate. The absorption of chlorpromazine may be reduced by chelation with magnesium sulfate.
Polyethylene Glycol; Electrolytes; Ascorbic Acid: (Major) Administer chlorpromazine at least 2 hours before or 6 hours after administration of magnesium sulfate; potassium sulfate; sodium sulfate. The absorption of chlorpromazine may be reduced by chelation with magnesium sulfate.
Ponesimod: (Major) In general, do not initiate ponesimod in patients taking chlorpromazine due to the risk of additive bradycardia, QT prolongation, and torsade de pointes (TdP). If treatment initiation is considered, seek advice from a cardiologist. Ponesimod initiation may result in a transient decrease in heart rate and atrioventricular conduction delays. Ponesimod has not been studied in patients taking concurrent QT prolonging drugs; however, QT prolonging drugs have been associated with TdP in patients with bradycardia. Chlorpromazine is associated with an established risk of QT prolongation and TdP.
Porfimer: (Major) Avoid coadministration of porfimer with phenothiazines due to the risk of increased photosensitivity. Porfimer is a light-activated drug used in photodynamic therapy; all patients treated with porfimer will be photosensitive. Concomitant use of other photosensitizing agents like phenothiazines may increase the risk of a photosensitivity reaction.
Posaconazole: (Major) Concurrent use of chlorpromazine and posaconazole should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Posaconazole has been associated with QT prolongation and in rare cases, TdP. Phenothiazines have also been associated with a QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Pramipexole: (Major) Due to opposing effects on central dopaminergic activity, phenothiazines and pramipexole may interfere with the effectiveness of each other. Avoid concurrent use if possible and consider an atypical antipsychotic as an alternative to the phenothiazine. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors. In addition, coadministration may result in additive sedation.
Pramlintide: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Pregabalin: (Major) Initiate pregabalin at the lowest recommended dose and monitor patients for symptoms of sedation and somnolence during coadministration of pregabalin and chlorpromazine. Concomitant use of pregabalin with chlorpromazine may cause additive CNS depression. Educate patients about the risks and symptoms of excessive CNS depression.
Pretomanid: (Major) Avoid coadministration of pretomanid with chlorpromazine, especially in patients with impaired hepatic function, due to increased risk for hepatotoxicity. Monitor for evidence of hepatotoxicity if coadministration is necessary. If new or worsening hepatic dysfunction occurs, discontinue hepatotoxic medications.
Prilocaine; Epinephrine: (Moderate) Monitor blood pressure during concomitant epinephrine and phenothiazine use. Phenothiazines antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by a phenothiazine, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Primaquine: (Major) Due to the potential for QT interval prolongation with primaquine, caution is advised with other drugs that prolong the QT interval. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously and with close monitoring with primaquine include chlorpromazine.
Primidone: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Procainamide: (Major) Procainamide administration is associated with QT prolongation and torsades de pointes (TdP). Phenothiazines have been associated with a risk of QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use.
Procarbazine: (Moderate) CNS depressants, such as phenothiazines, can potentiate the CNS depression caused by procarbazine therapy, so these drugs should be used together cautiously.
Prochlorperazine: (Moderate) Prochlorperazine, a phenothiazine, is associated with a possible risk for QT prolongation and chlorpromazine is associated with an established risk of QT prolongation and torsade de pointes. Coadministration of prochlorperazine and chlorpromazine may increase the risk of adverse effects such as QT prolongation, torsade de pointes, drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures.
Promethazine: (Major) The use of promethazine, a phenothiazine antiemetic, with phenothiazine antipsychotics such as chlorpromazine should be avoided if possible. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Promethazine has also been associated with QT prolongation. The duplicative actions of the drugs may result in an increased risk for side effects. Coadministration of promethazine and phenothiazine antipsychotics may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. Although the incidence of tardive dyskinesia from these combinations has not been established and data are very limited, the risk may be increased during combined use versus use of an antipsychotic alone.
Promethazine; Dextromethorphan: (Major) The use of promethazine, a phenothiazine antiemetic, with phenothiazine antipsychotics such as chlorpromazine should be avoided if possible. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Promethazine has also been associated with QT prolongation. The duplicative actions of the drugs may result in an increased risk for side effects. Coadministration of promethazine and phenothiazine antipsychotics may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. Although the incidence of tardive dyskinesia from these combinations has not been established and data are very limited, the risk may be increased during combined use versus use of an antipsychotic alone.
Promethazine; Phenylephrine: (Major) The use of promethazine, a phenothiazine antiemetic, with phenothiazine antipsychotics such as chlorpromazine should be avoided if possible. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Promethazine has also been associated with QT prolongation. The duplicative actions of the drugs may result in an increased risk for side effects. Coadministration of promethazine and phenothiazine antipsychotics may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. Although the incidence of tardive dyskinesia from these combinations has not been established and data are very limited, the risk may be increased during combined use versus use of an antipsychotic alone. (Moderate) Other non-cardiovascular drugs with alpha-blocking activity such as phenothiazines, directly counteract the effects of phenylephrine and can counter the desired pharmacologic effect. They also can be used to treat excessive phenylephrine-induced hypertension.
Propafenone: (Major) Concomitant use of propafenone and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Propantheline: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Propranolol: (Moderate) Monitor for an increase in chlorpromazine and propranolol-related adverse effects during concomitant use. The concentrations of both medications may increase; concomitant use has been observed to increase propranolol concentrations by 70%,
Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines. (Moderate) Monitor for an increase in chlorpromazine and propranolol-related adverse effects during concomitant use. The concentrations of both medications may increase; concomitant use has been observed to increase propranolol concentrations by 70%,
Protriptyline: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Pseudoephedrine; Triprolidine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as triprolidine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Pyrilamine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as pyrilamine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Pyrimethamine: (Major) Pyrimethamine has been shown in one report to reduce the hepatic metabolism of chlorpromazine, with markedly increased plasma concentrations of chlorpromazine and the 7-OH-chlorpromazine metabolite. Patients who are on stable chlorpromazine regimens should be monitored for increased phenothiazine effects if antimalarials, such as pyrimethamine, are added.
Quazepam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Quetiapine: (Major) Concurrent use of quetiapine and chlorpromazine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Limited data, including some case reports, suggest that quetiapine may also be associated with a significant prolongation of the QTc interval in rare instances. In addition, co-administration of quetiapine with phenothiazines may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. The likelihood of pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Quinidine: (Contraindicated) Quinidine administration is associated with QT prolongation and torsades de pointes (TdP). Quinidine inhibits CYP2D6 and has QT-prolonging actions; quinidine is contraindicated with other drugs that prolong the QT interval and are metabolized by CYP2D6 as the effects on the QT interval may be increased during concurrent use of these agents. Drugs that prolong the QT and are substrates for CYP2D6 that are contraindicated with quinidine include chlorpromazine.
Quinine: (Major) Concurrent use of quinine and chlorpromazine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Quinine has been associated with prolongation of the QT interval and rare cases of TdP. Chlorpromazine has also been associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. In addition, concentrations of chlorpromazine may be increased with concomitant use of quinine. Chlorpromazine is a CYP2D6 substrate and quinine is a CYP2D6 inhibitor.
Quizartinib: (Major) Concomitant use of quizartinib and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Ranolazine: (Major) Ranolazine is associated with dose- and plasma concentration-related increases in the QTc interval. The mean increase in QTc is about 6 milliseconds, measured at the tmax of the maximum dosage (1000 mg PO twice daily). However, in 5% of the population studied, increases in the QTc of at least 15 milliseconds have been reported. Although there are no studies examining the effects of ranolazine in patients receiving other QT prolonging drugs, coadministration of such drugs may result in additive QT prolongation. Ranolazine should be used cautiously with drugs that prolong the QT interval, such as chlorpromazine. In addition, ranolazine is metabolized mainly by CYP3A and to a lesser extent by CYP2D6. Chlorpromazine is a known CYP2D6 inhibitor; coadministration with ranolazine may result in increased plasma concentrations of ranolazine. The manufacturer specifies that no dosage adjustment of ranolazine is necessary when coadministering CYP2D6 inhibitors. Until further data are available, it is prudent to cautiously monitor the concurrent use of ranolazine and significant CYP2D6 inhibitors since potential increases in plasma concentrations of ranolazine may result in adverse effects.
Rasagiline: (Major) Due to opposing effects on central dopaminergic activity, phenothiazines and rasagiline may interfere with the effectiveness of each other. Avoid concurrent use if possible and consider an atypical antipsychotic to the phenothiazine, if appropriate. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors.
Relugolix: (Major) Consider whether the benefits of androgen deprivation therapy outweigh the potential risks in patients receiving other QT prolonging agents such as chlorpromazine. Androgen deprivation therapy (i.e., relugolix) may prolong the QT/QTc interval. Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and torsade de pointes (TdP).
Relugolix; Estradiol; Norethindrone acetate: (Major) Consider whether the benefits of androgen deprivation therapy outweigh the potential risks in patients receiving other QT prolonging agents such as chlorpromazine. Androgen deprivation therapy (i.e., relugolix) may prolong the QT/QTc interval. Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and torsade de pointes (TdP).
Remifentanil: (Moderate) Phenothiazines can potentiate the CNS depressant action of other drugs such as opiate agonists. A dose reduction of one or both drugs may be warranted.
Remimazolam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Ribociclib: (Major) Avoid coadministration of ribociclib with chlorpromazine due to an increased risk for QT prolongation and torsade de pointes (TdP). Ribociclib has been shown to prolong the QT interval in a concentration-dependent manner. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Concomitant use may increase the risk for QT prolongation.
Ribociclib; Letrozole: (Major) Avoid coadministration of ribociclib with chlorpromazine due to an increased risk for QT prolongation and torsade de pointes (TdP). Ribociclib has been shown to prolong the QT interval in a concentration-dependent manner. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. Concomitant use may increase the risk for QT prolongation.
Rifabutin: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of ri fampin or another rifamycin.
Rifampin: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Rifamycins: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Rifapentine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Rilpivirine: (Major) Concurrent use of chlorpromazine and rilpivirine should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Supratherapeutic doses of rilpivirine (75 to 300 mg/day) have caused QT prolongation. Phenothiazines have also been associated with QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Riluzole: (Moderate) Monitor for signs and symptoms of hepatic injury during coadministration of riluzole and chlorpromazine. Concomitant use may increase the risk for hepatotoxicity. Discontinue riluzole if clinical signs of liver dysfunction are present.
Risperidone: (Major) Risperidone has been associated with a possible risk for QT prolongation and/or torsade de pointes; however, data are currently lacking to establish causality in association with torsades de pointes (TdP). Reports of QT prolongation and torsades de pointes during risperidone therapy are noted by the manufacturer, primarily in the overdosage setting. Since risperidone may prolong the QT interval, it should be used cautiously with other agents also known to have this effect, taking into account the patient's underlying disease state(s) and additional potential risk factors. If coadministration is chosen, and the patient has known risk factors for cardiac disease or arrhythmia, then the patient should be closely monitored clinically. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously with risperidone include chlorpromazine. In addition, coadministration may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Rivastigmine: (Moderate) Conventional antipsychotics with significant anticholinergic effects, such as chlorpromazine, are more likely than other conventional antipsychotics to diminish the therapeutic action of rivastigmine, and use of an alternative antipsychotic should be considered. Rivastigmine inhibits acetylcholinesterase, the enzyme responsible for the degradation of acetylcholine, and exerts its therapeutic effect by improving the availability of acetylcholine. Consider the use of an antipsychotic with less prominent anticholinergic effects.
Rolapitant: (Major) Monitor for chlorpromazine-related adverse effects, including QT prolongation and torsade de pointes (TdP), if coadministered with rolapitant. Increased exposure to chlorpromazine may occur. Chlorpromazine is a CYP2D6 substrate and rolapitant is a moderate CYP2D6 inhibitor; the inhibitory effect of rolapitant is expected to persist beyond 28 days for an unknown duration. Exposure to another CYP2D6 substrate, following a single dose of rolapitant increased about 3-fold on Days 8 and Day 22. The inhibition of CYP2D6 persisted on Day 28 with a 2.3-fold increase in the CYP2D6 substrate concentrations, the last time point measured.
Romidepsin: (Major) Romidepsin has been reported to prolong the QT interval. If romidepsin must be coadministered with another drug that prolongs the QT interval, such as chlorpromazine, appropriate cardiovascular monitoring precautions should be considered, such as the monitoring of electrolytes and ECGs at baseline and periodically during treatment. Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Ropinirole: (Major) Due to opposing effects on central dopaminergic activity, phenothiazines and ropinirole may interfere with the effectiveness of each other. Avoid concurrent use if possible and consider an atypical antipsychotic as an alternative to the phenothiazine. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors.
Rosiglitazone: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Rotigotine: (Major) Due to opposing effects on central dopaminergic activity, phenothiazines and rotigotine may interfere with the effectiveness of each other. Avoid concurrent use if possible and consider an atypical antipsychotic as an alternative to the phenothiazine. If coadministration cannot be avoided, monitor for changes in movement, moods, or behaviors. In addition, coadministration may result in additive sedation.
Safinamide: (Major) Due to opposing effects on central dopaminergic activity, phenothiazines and safinamide may interfere with the effectiveness of each other. Avoid concurrent use if possible and consider an atypical antipsychotic as an alternative to the phenothiazine if appropriate. If coadministration cannot be avoided, monitor for changes in movements, moods, or behaviors.
Saquinavir: (Contraindicated) Concurrent use of chlorpromazine and saquinavir is contraindicated due to an increased risk for QT prolongation and torsade de pointes (TdP). Saquinavir boosted with ritonavir increases the QT interval in a dose-dependent fashion, which may increase the risk for serious arrhythmias such as TdP. Chlorpromazine is also associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Saxagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Scopolamine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Secobarbital: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered concurrently and they should be used cautiously with anxiolytic, sedative, and hypnotic type drugs, such as the barbiturates. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Phenothiazines can also lower the seizure threshold, which may be important in patients taking a barbiturate for the treatment of seizures. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of other CNS depressants than with the use of sedatives alone. Monitor for additive effects, unusual moods or behaviors, and warn about the potential effects to driving and other activities.
Segesterone Acetate; Ethinyl Estradiol: (Minor) Oral contraceptives may also cause additive photosensitization with phenothiazines.
Selegiline: (Moderate) Monitor for unusual drowsiness and sedation during coadministration of phenothiazines and selegiline due to the risk for additive CNS depression. It is also possible that dopamine antagonists, such as phenothiazines, could diminish the effectiveness of selegiline.
Selpercatinib: (Major) Monitor ECGs more frequently for QT prolongation if coadministration of selpercatinib with chlorpromazine is necessary due to the risk of additive QT prolongation. Concentration-dependent QT prolongation has been observed with selpercatinib therapy. Chlorpromazine is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Sertraline: (Major) Use caution and monitor patients for QT prolongation when administering chlorpromazine with sertraline. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). QTc prolongation and TdP have been reported during postmarketing use of sertraline; most cases had confounding risk factors. The risk of sertraline-induced QT prolongation is generally considered to be low in clinical practice. Its effect on QTc interval is minimal (typically less than 5 msec), and the drug has been used safely in patients with cardiac disease (e.g., recent myocardial infarction, unstable angina, chronic heart failure). In addition, sertraline is a CYP2D6 inhibitor and chlorpromazine is a CYP2D6 substrate. Decreased metabolism of chlorpromazine may lead to adverse effects such as arrhythmias, orthostatic hypotension, excessive sedation, or extrapyramidal symptoms.
Sevoflurane: (Major) Halogenated anesthetics should be used cautiously and with close monitoring with chlorpromazine. Halogenated anesthetics can prolong the QT interval. Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use. In addition, phenothiazines can potentiate the CNS-depressant action of anesthetics.
SGLT2 Inhibitors: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted.
Siponimod: (Major) In general, do not initiate treatment with siponimod in patients receiving chlorpromazine due to the potential for QT prolongation. Consult a cardiologist regarding appropriate monitoring if siponimod use is required. Siponimod therapy prolonged the QT interval at recommended doses in a clinical study. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes.
Sitagliptin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Sodium Oxybate: (Major) Additive CNS depressant effects may be possible when sodium oxybate is used concurrently with phenothiazines.
Sodium picosulfate; Magnesium oxide; Anhydrous citric acid: (Major) Chlorpromazine may chelate with the magnesium in sodium picosulfate; magnesium oxide; anhydrous citric acid solution. Therefore, chlorpromazine should be taken at least 2 hours before and not less than 6 hours after the administration of sodium picosulfate; magnesium oxide; anhydrous citric acid solution.
Sodium Stibogluconate: (Major) Concomitant use of sodium stibogluconate and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Solifenacin: (Major) Chlorpromazine should be used cautiously and with close monitoring with solifenacin. Solifenacin has been associated with dose-dependent prolongation of the QT interval. Torsades de pointes (TdP) has been reported with post-marketing use, although causality was not determined. Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use.
Sorafenib: (Major) Avoid coadministration of sorafenib with chlorpromazine due to the risk of additive QT prolongation. If concomitant use is unavoidable, monitor electrocardiograms and correct electrolyte abnormalities. An interruption or discontinuation of sorafenib therapy may be necessary if QT prolongation occurs. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Sorafenib is also associated with QTc prolongation.
Sotagliflozin: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should be closely monitored for worsening glycemic control when any of these antipsychotics is instituted.
Sotalol: (Major) Concomitant use of sotalol and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Stiripentol: (Moderate) Monitor for excessive sedation and somnolence during coadministration of stiripentol and chlorpromazine. CNS depressants can potentiate the effects of stiripentol.
Streptomycin: (Minor) When used for the treatment of nausea and vomiting, antiemetic phenothiazines may effectively mask symptoms that are associated with ototoxicity induced by the aminoglycosides.
Sufentanil: (Moderate) Phenothiazines can potentiate the CNS depressant action of other drugs such as opiate agonists. A dose reduction of one or both drugs may be warranted.
Sulfonylureas: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure.
Sunitinib: (Major) Monitor patients for QT prolongation if coadministration of chlorpromazine with sunitinib is necessary. Sunitinib can cause dose-dependent QT prolongation, which may increase the risk for ventricular arrhythmias, including torsades de points (TdP). Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and TdP.
Tacrolimus: (Major) Due to a possible risk for QT prolongation and torsade de pointes (TdP), tacrolimus and chlorpromazine should be used together cautiously. Tacrolimus causes QT prolongation. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP.
Tamoxifen: (Major) Concomitant use of tamoxifen and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Tamsulosin: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpromazine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Tapentadol: (Major) Concomitant use of opioid agonists with chlorpromazine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chlorpromazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
Tazarotene: (Moderate) The manufacturer states that tazarotene should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as phenothiazines, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
Telavancin: (Major) Concurrent use of chlorpromazine and telavancin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Telavancin has been associated with QT prolongation. Phenothiazines have also been associated with a risk of QT prolongation and/or TdP. This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Temazepam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Tetrabenazine: (Major) Tetrabenazine causes a small increase in the corrected QT interval (QTc). The manufacturer recommends avoiding concurrent use of tetrabenazine with other drugs known to prolong QTc such as chlorpromazine. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. In addition, concurrent use of these medications and tetrabenazine should generally be avoided since the risk of adverse effects such as drowsiness, sedation, dizziness, orthostatic hypotension, neuroleptic malignant syndrome, or extrapyramidal symptoms may be increased.
Thalidomide: (Major) Avoid the concomitant use of thalidomide with opiate agonists; antihistamines; antipsychotics; anxiolytics, sedatives, and hypnotics; and other central nervous system depressants due to the potential for additive sedative effects.
Thiazide diuretics: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Thiazolidinediones: (Minor) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted.
Thioridazine: (Contraindicated) Thioridazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP) and is contraindicated for use with other drugs that are known to prolong the QT interval, such as chlorpromazine. In addition, coadministration may increase the risk of drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, or seizures.
Thiothixene: (Major) Caution is advisable during concurrent use of thiothixene and the phenothiazine antipsychotics. Thiothixene use has been associated with adverse events such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, and seizures. These effects may be potentiated during concurrent use of phenothiazines and other antipsychotics. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the co-administered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone. Administration of thiothixene with antipsychotics that are metabolized by CYP2D6, such as phenothiazines, should be approached with great caution. Thiothixene has been shown to inhibit CYP2D6 in vitro and serum concentrations of phenothiazines may increase.
Tiagabine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Tobacco: (Major) Advise patients to avoid smoking tobacco while taking phenothiazines. Tobacco smoking may increase the clearance of phenothiazines, which may reduce their efficacy.
Tobramycin: (Minor) When used for the treatment of nausea and vomiting, antiemetic phenothiazines may effectively mask symptoms that are associated with ototoxicity induced by the aminoglycosides.
Tolazamide: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure.
Tolbutamide: (Moderate) Phenothiazines, especially chlorpromazine, may increase blood glucose concentrations. Hyperglycemia and glycosuria have been reported. Patients who are taking antidiabetic agents should monitor for worsening glycemic control when a phenothiazine is instituted. Also, concomitant use may increase the risk for phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure.
Tolterodine: (Major) Depending on the specific agent, additive anticholinergic effects may be seen when drugs with antimuscarinic properties like tolterodine are used concomitantly with other antimuscarinics like most phenothiazines. Clinicians should note that additive antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the CNS, the eye, and temperature regulation. Additive drowsiness may also occur, depending on the interacting agent. In addition, tolterodine is associated with dose-dependent prolongation of the QT interval, especially in poor metabolizers of CYP2D6. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine and should be used cautiously and with close monitoring with tolterodine.
Topiramate: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Toremifene: (Major) Avoid coadministration of chlorpromazine with toremifene if possible due to the risk of additive QT prolongation. If concomitant use is unavoidable, closely monitor ECGs for QT prolongation and monitor electrolytes; correct hypokalemia or hypomagnesemia prior to administration of toremifene. Toremifene has been shown to prolong the QTc interval in a dose- and concentration-related manner. Chlorpromazine, a phenothiazine, is also associated with an established risk of QT prolongation and torsade de pointes (TdP).
Tramadol: (Moderate) Concurrent use of tramadol and chlorpromazine should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. In addition, in vitro data suggest that chlorpromazine has CYP2D6 inhibitory effects and has the potential to decrease the metabolism of CYP2D6 substrates such as tramadol. Although the full pharmacologic impact of increased tramadol exposure is unknown, close monitoring for serious adverse effects, such as seizures, is advisable. In addition, serotonin syndrome may occur during use of tramadol with medications that impair its metabolism. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, hyperreflexia, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Because the analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), CYP2D6 inhibition by chlorpromazine may alter the analgesic response to tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and chlorpromazine.
Tramadol; Acetaminophen: (Moderate) Concurrent use of tramadol and chlorpromazine should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. In addition, in vitro data suggest that chlorpromazine has CYP2D6 inhibitory effects and has the potential to decrease the metabolism of CYP2D6 substrates such as tramadol. Although the full pharmacologic impact of increased tramadol exposure is unknown, close monitoring for serious adverse effects, such as seizures, is advisable. In addition, serotonin syndrome may occur during use of tramadol with medications that impair its metabolism. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, hyperreflexia, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Because the analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), CYP2D6 inhibition by chlorpromazine may alter the analgesic response to tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and chlorpromazine.
Tranylcypromine: (Moderate) Due to the potential for additive CNS and cardiovascular effects, MAOIs and phenothiazines should be used together cautiously. Concurrent use of MAOIs and phenothiazines may prolong or intensify the hypotensive, anticholinergic, or sedative effects of either agent.
Trazodone: (Major) Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP) and should be avoided in combination with trazodone. Trazodone can prolong the QT/QTc interval at therapeutic doses. In addition, there are post-marketing reports of TdP. Therefore, the manufacturer recommends avoiding trazodone in patients receiving other drugs that increase the QT interval. In addition, CNS depressants, such as phenothiazines, should be used cautiously in patients receiving trazodone because of additive CNS-depressant effects, including possible respiratory depression or hypotension.
Tretinoin, ATRA: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as phenothiazines, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
Tretinoin; Benzoyl Peroxide: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as phenothiazines, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Triazolam: (Major) Limit dosage and duration of benzodiazepines during concomitant phenothiazine use and monitor for unusual drowsiness and sedation due to the risk for additive CNS depression.
Triclabendazole: (Major) Concomitant use of triclabendazole and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Tricyclic antidepressants: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Trifluoperazine: (Moderate) Coadministration of chlorpromazine and trifluoperazine should be avoided if possible due to the risk of QT prolongation and other adverse effects. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Trifluoperazine is also a phenothiazine and is associated with a possible risk for QT prolongation. Coadministration may also increase the risk of drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, tardive dyskinesia, or seizures.
Trihexyphenidyl: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
Trimethobenzamide: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Trimipramine: (Moderate) During coadministration of tricyclic antidepressants (TCAs) and chlorpromazine, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Chlorpromazine is associated with an established risk of QT prolongation and torsades de pointes (TdP); case reports have included patients receiving therapeutic doses of chlorpromazine. TCAs may cause cardiac effects (e.g., QT prolongation) in some cases. Additive anticholinergic effects, hypotension, and sedation may also occur.
Triprolidine: (Moderate) Additive anticholinergic and sedative effects may be seen when chlorpromazine is used with first generation antihistamines, such as triprolidine. Patients should be informed to read non-prescription cough and cold product labels carefully for additional interacting antihistamines.
Triptorelin: (Major) Avoid coadministration of triptorelin with chlorpromazine due to the risk of reduced efficacy of triptorelin; QT prolongation may also occur. Chlorpromazine can cause hyperprolactinemia, which reduces the number of pituitary gonadotropin releasing hormone (GnRH) receptors; triptorelin is a GnRH analog. Additionally, chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP). Androgen deprivation therapy (i.e., triptorelin) may also prolong the QT/QTc interval.
Trospium: (Moderate) Additive anticholinergic effects may be seen when phenothiazines are used concomitantly with other drugs with antimuscarinic activity, such as trospium.
Valproic Acid, Divalproex Sodium: (Moderate) The phenothiazines, when used concomitantly with various anticonvulsants, such as valproic acid, can increase CNS depression and also can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added; patients should be monitored for clinical evidence of loss of seizure control or the need for dosage adjustments of either the phenothiazine or the anticonvulsant.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor blood pressure during concomitant thiazide diuretic and phenothiazine use. Thiazide diuretics may potentiate the orthostatic hypotension that may occur with phenothiazines.
Vandetanib: (Major) Avoid coadministration of vandetanib with chlorpromazine due to an increased risk of QT prolongation and torsade de pointes (TdP). If concomitant use is unavoidable, monitor ECGs for QT prolongation and monitor electrolytes; correct hypocalcemia, hypomagnesemia, and/or hypomagnesemia prior to vandetanib administration. An interruption of vandetanib therapy or dose reduction may be necessary for QT prolongation. Vandetanib can prolong the QT interval in a concentration-dependent manner; TdP and sudden death have been reported in patients receiving vandetanib. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and torsade de pointes (TdP).
Vardenafil: (Major) Concomitant use of vardenafil and chlorpromazine increases the risk of QT/QTc prolongation and torsade de pointes (TdP). Avoid concomitant use if possible, especially in patients with additional risk factors for TdP. Consider taking steps to minimize the risk for QT/QTc interval prolongation and TdP, such as electrolyte monitoring and repletion and ECG monitoring, if concomitant use is necessary.
Vemurafenib: (Major) Vemurafenib has been associated with QT prolongation. Coadministration of vemurafenib and another drug, such as chlorpromazine, that is associated with a possible risk for QT prolongation and torsade de pointes (TdP) are generally not recommended for combined use. If coadministration is necessary, ECG monitoring is recommended; closely monitor the patient for QT interval prolongation. Also, chlorpromazine is a CYP2D6 substrate, while vemurafenib is a weak CYP2D6 inhibitor; therefore, increased concentrations of chlorpromazine may occur with concomitant use.
Venlafaxine: (Major) Chlorpromazine is associated with a possible risk of QT prolongation and should be used cautiously with venlafaxine since venlafaxine is also associated with a possible risk of QT prolongation. In addition, venlafaxine is an inhibitor of CYP2D6, and concurrent use with CYP2D6 substrates, such as phenothiazines, may result in increased plasma concentrations of such antipsychotics. In one case report, the initiation of venlafaxine in a patient taking trifluoperazine resulted in symptoms consistent with neuroleptic malignant syndrome (NMS). After discontinuation of all psychiatric medications and treatment for NMS, the patient recovered and was able to reinitiate trifluoperazine without further problems. Venlafaxine was not administered a second time.
Verteporfin: (Moderate) Use caution if coadministration of verteporfin with phenothiazines is necessary due to the risk of increased photosensitivity. Verteporfin is a light-activated drug used in photodynamic therapy; all patients treated with verteporfin will be photosensitive. Concomitant use of other photosensitizing agents like phenothiazines may increase the risk of a photosensitivity reaction.
Vigabatrin: (Major) Vigabatrin should not be used with phenothiazines, which is associated with serious ophthalmic effects (e.g., retinopathy or glaucoma) unless the benefit of treatment clearly outweighs the risks.
Viloxazine: (Moderate) Monitor for an increase in chlorpromazine-related adverse reactions, including QT prolongation, anticholinergic effects, orthostasis, and somnolence, if coadministration with viloxazine is necessary. Concomitant use may increase chlorpromazine exposure. Chlorpromazine is a CYP2D6 substrate and viloxazine is a weak CYP2D6 inhibitor.
Voclosporin: (Major) Use caution if chlorpromazine is coadministered with voclosporin due to the risk of additive QT prolongation. Chlorpromazine is associated with an established risk of QT prolongation and torsade de pointes (TdP). Voclosporin has been associated with QT prolongation at supratherapeutic doses.
Vonoprazan; Amoxicillin; Clarithromycin: (Major) Concurrent use of chlorpromazine and clarithromycin should be avoided due to an increased risk for QT prolongation and torsade de pointes (TdP). Both clarithromycin and chlorpromazine are specifically associated with an established risk of QT prolongation and TdP.
Voriconazole: (Major) Due to the potential for QT prolongation and torsade de pointes (TdP), caution is advised when administering voriconazole with chlorpromazine. Voriconazole has been associated with prolongation of the QT interval and rare cases of arrhythmias, including TdP. Chlorpromazine is also associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine.
Vorinostat: (Major) Phenothiazines have been associated with a risk of QT prolongation and/or torsade de pointes (TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval, such as vorinostat, could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use.
Zaleplon: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered with other CNS depressant drugs and they should be used cautiously with anxiolytic, sedative, and hypnotics. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of hypnotics and other CNS depressants than with use of a hypnotic alone.
Ziconotide: (Moderate) Due to potentially additive effects, dosage adjustments may be necessary if ziconotide is used with a drug that has CNS depressant effects such as phenothiazines. Coadministration of CNS depressants may increase drowsiness, dizziness, and confusion that are associated with ziconotide.
Ziprasidone: (Contraindicated) Concomitant use of ziprasidone and chlorpromazine is contraindicated by the manufacturer of ziprasidone due to the potential for additive QT prolongation and torsade de pointes (TdP). Clinical trial data indicate that ziprasidone causes QT prolongation; there are postmarketing reports of torsade de pointes (TdP) in patients with multiple confounding factors. Chlorpromazine, a phenothiazine, is associated with an established risk of QT prolongation and TdP. In addition, coadministration of ziprasidone with phenothiazines may increase the risk of adverse effects such as drowsiness, dizziness, orthostatic hypotension, anticholinergic effects, extrapyramidal symptoms, neuroleptic malignant syndrome, or seizures. The likelihood of these pharmacodynamic interactions varies based upon the individual properties of the coadministered antipsychotic agent. Although the incidence of tardive dyskinesia from combination antipsychotic therapy has not been established and data are very limited, the risk appears to be increased during use of a conventional and atypical antipsychotic versus use of a conventional antipsychotic alone.
Zolpidem: (Moderate) Phenothiazines are CNS depressant drugs that may have cumulative effects when administered with other CNS depressant drugs and they should be used cautiously with anxiolytic, sedative, and hypnotics. Caution should be exercised during simultaneous use of these agents due to potential excessive CNS effects or additive hypotension. Additionally, sleep-related behaviors, such as sleep-driving, are more likely to occur during concurrent use of hypnotics and other CNS depressants than with use of a hypnotic alone.
Zonisamide: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added. Zonisamide may also cause decreased sweating (oligohidrosis), elevated body temperature (hyperthermia), heat intolerance, or heat stroke. The manufacturer recommends caution in using concurrent drug therapies that may predispose patients to heat-related disorders such as antipsychotic phenothiazines. Monitor patients for decreased efficacy of the anticonvulsant, heat intolerance, decreased sweating, or increased body temperature if zonisamide is used with any of these agents.
How Supplied
Chlorpromazine/Chlorpromazine Hydrochloride Oral Sol: 1mL, 30mg, 100mg
Chlorpromazine/Chlorpromazine Hydrochloride/Thorazine Intramuscular Inj Sol: 1mL, 25mg
Chlorpromazine/Chlorpromazine Hydrochloride/Thorazine Oral Tab: 10mg, 25mg, 50mg, 100mg, 200mg
Maximum Dosage
1000 mg/day PO; up to 2000 mg/day PO for short periods. Debilitated patients require lower total daily dosages.
Elderly1000 mg/day PO. Debilitated patients require lower total daily dosages.
Adolescents1000 mg/day PO; up to 2000 mg/day PO for short periods. Debilitated patients require lower total daily dosages.
Children5—12 years (weight 22.7—45.5 kg): 100—200 mg/day PO or 75 mg/day IM.
1—4.9 years (weight < 22.7 kg): 50 mg/day PO or 40 mg/day IM.
>= 6 months (weight < 22.7 kg): 50 mg/day PO or 40 mg/day IM.
Mechanism Of Action
Chlorpromazine's principal pharmacological actions are psychotropic. It also exerts sedative and antiemetic activity. Chlorpromazine has actions at all levels of the central nervous system - primarily at subcortical levels-as well as on multiple organ systems. The drug blocks postsynaptic dopamine receptors in the mesolimbic system and increases dopamine turnover by blockade of the dopamine D2 somatodendritic autoreceptor. After about 12 weeks of chronic therapy, depolarization blockade of dopamine tracts occurs. The decrease in dopamine neurotransmission has been found to be correlated to the antipsychotic effects. This D2 blockade is also responsible for the moderate extrapyramidal effects observed with this drug. Dopamine blockade in the chemoreceptor trigger zone accounts for the antiemetic effects. Chlorpromazine possesses strong anticholinergic and alpha-adrenergic receptor blocking effects. Blockade of alpha1-adrenergic receptors produces sedation, muscle relaxation, and cardiovascular effects such as hypotension, reflex tachycardia, and minor changes in ECG patterns.
Pharmacokinetics
Chlorpromazine is administered by oral, intravenous, and intramuscular routes. Antipsychotic effects are gradual, with considerable individual patient variation. Peak effects may not occur for 6 weeks to 6 months. Chlorpromazine is extensively distributed into body tissues and fluids. Chlorpromazine is 90% to 99% bound to plasma protein, predominantly alpha-1 acid glycoprotein. Metabolism is extensive, and more than 100 metabolites have been identified. The metabolism of oral chlorpromazine is biphasic, with an initial half-life of 2 hours and a terminal half-life of 30 hours. Enterohepatic circulation takes place, and some metabolites may be pharmacologically active, notably 7-hydroxychlorpromazine, which is approximately equipotent with haloperidol and has a half-life of 10 to 40 hours. There is some conjugation with glucuronides, and these, along with unconjugated metabolites, account for most of the drug found in urine; only about 1% is excreted as unchanged drug. There may be some correlation between the amount of excretion of unconjugated 7-hydroxychlorpromazine and the development of hyperpigmentation of the skin. Chlorpromazine is partially excreted via the biliary tract and feces.
Affected cytochrome P450 (CYP450) isoenzymes and drug transporters: CYP2D6, CYP1A2, CYP3A4
CYP2D6 is the primary isoenzyme involved in the metabolism of chlorpromazine, with CYP1A2 and CYP3A4 having a minor role. In vitro data suggest that chlorpromazine has relatively moderate CYP2D6 inhibitory effects compared to other phenothiazines and has the potential to decrease the metabolism of CYP2D6 substrates.
Chlorpromazine is rapidly absorbed following oral administration, but there is considerable individual patient variation in peak plasma concentrations because the drug undergoes metabolism in the gastric mucosa and during first pass through the liver. The oral bioavailability is 32% (range: 19% to 51%). The time to peak concentrations is 2.8 hours. After oral ingestion, the onset of sedation occurs within 30 to 60 minutes and lasts for 4 to 18 hours.
Other Route(s)Rectal Route
Administered rectally, chlorpromazine's antinauseant actions are delayed, with a duration of 3 to 4 hours.
Pregnancy And Lactation
No well-controlled data are available to determine the safety and efficacy of chlorpromazine during human pregnancy; therefore, the drug should be used only when the benefits to the mother outweigh the potential risks to the fetus. The American College of Obstetricians and Gynecologists (ACOG) include chlorpromazine as a last-line treatment option for treating nausea and vomiting of pregnancy in patients who have failed other therapies. Phenothiazines readily cross the placenta. Whether there is an increased risk of major malformations with routine use during pregnancy has not been clearly established. Data collected from the Swedish Medical Birth Registry showed an increased risk of major malformations (e.g., atrial or ventricular septal defects) with an estimated odds ratio of 1.52. The investigators analyzed registry data from 576 infants exposed to antipsychotics in utero. Of the 8 infants exposed to chlorpromazine, there were no major malformations reported. Among the 201 women exposed to any phenothiazine during early pregnancy, there was a 3% incidence of malformations. Other findings included a nearly doubling of the risk for gestational diabetes and a 40% increased risk for cesarean delivery. Of the 14 women who developed gestational diabetes, 1 was exposed to chlorpromazine. Because no certain drug specificity was found for the observed outcomes, the authors concluded that underlying pathology or unidentified confounders could possibly explain the findings. Adverse effects such as extrapyramidal symptoms, agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, and feeding disorder have been reported after delivery in neonates exposed to antipsychotics during the third trimester. These effects have varied in severity from self-limited to requiring intensive care unit stays and prolonged hospitalization. Neonates exhibiting signs or symptoms of extrapyramidal effects or withdrawal should be carefully monitored. The impact of in utero exposure to antidepressants or antipsychotics compared to no psychotropic exposure was assessed in infants 6 months of age using the Infant Neurological International Battery (INFANIB), a neuromotor exam that tests posture, tone, reflexes, and motor skills, and using a visual habituation paradigm of a neutral female face. The infants exposed to antipsychotics (n = 22) showed significantly lower INFANIB scores than those exposed to an antidepressant (n = 202) or no psychotropic drug (n = 85). There were no significant differences regarding habituation between the medication exposure groups. The knowledge about long-term neurobehavioral effects is limited for all antipsychotics and requires further investigation. In addition, there is consistent evidence of an increased likelihood of preterm delivery associated with conventional antipsychotic use during pregnancy, with one study reporting an odds ratio of 2.46 following exposure to a conventional antipsychotic. According to the American Psychiatric Association treatment guidelines for schizophrenia, consider pregnancy testing in women of childbearing potential prior to initiation of an antipsychotic. The National Pregnancy Registry for Psychiatric Medications is dedicated to evaluating the safety of psychiatric medications that may be taken by women during pregnancy to treat a wide range of mood, anxiety, or psychiatric disorders. One goal of this registry is to determine the frequency of major malformations, such as heart defects, cleft lip, or neural tube defects, in babies exposed to various psychiatric drugs during pregnancy; therefore, patient registration is encouraged. For more information, contact the registry at https://womensmentalhealth.org/clinical-and-research-programs/pregnancyregistry or by phone 1-866-961-2388. If phenothiazines must be given short-term for nausea or other necessary purposes during labor and obstetric delivery, it is prudent to monitor heart rate and blood pressure to detect possible maternal or fetal hypotension or other effects. It is not known if antipsychotics, through their effect on prolactin, affect labor or obstetric delivery.