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Drug Interactions between clozapine and gepirone

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Major

cloZAPine gepirone

Applies to: clozapine and gepirone

Consumer information for this interaction is not currently available.

MONITOR CLOSELY: Clozapine has the potential to prolong QT interval of the electrocardiogram. Theoretically, coadministration with other agents that can cause QT prolongation may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. Clozapine treatment alone has been associated with ventricular arrhythmia, torsade de pointes, cardiac arrest, and sudden death. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia, hypocalcemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s). Certain QT-prolonging agents (e.g., neuroleptics; phenothiazines; tricyclic antidepressants; some antihistamines, antispasmodics, and skeletal muscle relaxants) may also have additive parasympatholytic and central nervous system-depressant effects with clozapine. Excessive parasympatholytic effects can result in paralytic ileus, hyperthermia, mydriasis, blurred vision, tachycardia, urinary retention, psychosis, and seizures.

MANAGEMENT: Caution is recommended if clozapine is used in combination with other drugs that can prolong the QT interval. Serum electrolytes, including potassium, magnesium and calcium, should be measured at baseline and periodically during treatment, and any abnormalities corrected prior to initiating clozapine. Routine ECG assessment may detect QTc prolongation, but is not always effective in preventing arrhythmias. Clozapine treatment should be discontinued if the QTc interval exceeds 500 msec. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope. Additional precaution is required when using QT-prolonging agents with anticholinergic properties, particularly in the elderly and those with underlying organic brain disease. Patients should be advised to notify their physician if they experience potential symptoms of anticholinergic intoxication such as abdominal pain, fever, heat intolerance, blurred vision, confusion, and/or hallucinations. Dosage adjustments may be necessary if excessive adverse effects develop. Ambulatory patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.

References

  1. "Product Information. Clozaril (clozapine)." Novartis Pharmaceuticals PROD (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
  4. Cerner Multum, Inc. "Australian Product Information." O 0
  5. EMA. European Medicines Agency. European Union "EMA - List of medicines under additional monitoring. http://www.ema.europa.eu/ema/index.jsp?curl=pages/regulation/document_listing/document_listing_000366.jsp&mid=WC0b01ac058067c852" (2013):
View all 5 references

Drug and food interactions

Moderate

cloZAPine food

Applies to: clozapine

Alcohol can increase the nervous system side effects of cloZAPine such as dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment. You should avoid or limit the use of alcohol while being treated with cloZAPine. Do not use more than the recommended dose of cloZAPine, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have any questions or concerns.

Switch to professional interaction data

Moderate

gepirone food

Applies to: gepirone

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Grapefruit and/or grapefruit juice may increase the plasma concentrations and effects of gepirone. The proposed mechanism is inhibition of CYP450 3A4 mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice, but has been reported for other CYP450 3A4 inhibitors. For example, when subjects who were at steady state on the strong CYP450 3A4 inhibitor ketoconazole (200 mg twice daily) received a single dose of gepirone (36.3 mg), the maximum plasma concentration (Cmax) and systemic exposure (AUC) of gepirone increased by approximately 5-fold. Similarly, when subjects who were at steady state on the moderate CYP450 3A4 inhibitor verapamil (80 mg three times daily) received a single dose of gepirone (18.2 mg), the maximum plasma concentration (Cmax) and systemic exposure (AUC) of gepirone increased by approximately 2.6-fold. In general, the effects of grapefruit products are concentration-, dose-, and preparation-dependent and can vary widely among both brands and individual patients. Some preparations have demonstrated strong CYP450 3A4 inhibition, while others have demonstrated moderate inhibition.

ADJUST DOSING INTERVAL: Food enhances the bioavailability of gepirone and its major active metabolites (3'-OH-gepirone and 1-PP). The magnitude of the effect is dependent on the fat content of the meal, but the systemic exposure of gepirone and its major metabolites was consistently higher under fed conditions as compared to the fasted state. The peak plasma concentration (Cmax) of gepirone after intake of a low-fat (about 200 calorie) breakfast was 27% higher, after a medium-fat (about 500 calorie) breakfast was 55% higher, and after a high-fat (about 850 calorie) breakfast was 62% higher than the Cmax achieved in the fasted state. Likewise, the systemic exposure (AUC) of gepirone was about 14% higher after a low-fat breakfast, 22% higher after a medium-fat breakfast, and 32% to 37% higher after a high-fat breakfast when compared to the AUC achieved in the fasted state. The effect of varying amounts of fat on the AUC and Cmax of 3'-OH-gepirone and 1-PP were similar to that of gepirone.

MANAGEMENT: Coadministration of gepirone with grapefruit products should be avoided. If grapefruit juice is consumed, monitoring for adverse effects (e.g., QT prolongation, serotonin syndrome, dizziness, nausea, insomnia, abdominal pain, and/or dyspepsia) should be considered. Gepirone should be taken orally with food at the approximately the same time each day. Tablets should be swallowed whole.

References

  1. "Product Information. Exxua (gepirone)." Mission Pharmacal Company 1 (2023):
  2. FDA. U.S. Food and Drug Administration "Grapefruit juice and some drugs don't mix. https://www.fda.gov/consumers/consumer-updates/grapefruit-juice-and-some-drugs-dont-mix" (2024):
  3. Chen M, Zhou S, Fabriaga E, Zhang P, Zhou Q "Food-drug interactions precipitated by fruit juices other than grapefruit juice: an update review. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9326888/" (2024):
  4. Kiani J, Imam SZ "Medicinal importance of grapefruit juice and its interaction with various drugs. https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-6-33" (2024):
View all 4 references
Minor

cloZAPine food

Applies to: clozapine

Information for this minor interaction is available on the professional version.

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

See also

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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