Drug interactions
Clozapine + Diltiazem
Severity: Moderate
Clozapine and Diltiazem: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Diltiazem may increase clozapine concentrations, raising the risk of sedation, seizures, hypotension and cardiac effects.
What this interaction means in plain words
Clozapine and Diltiazem can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Clozapine belongs to Central Nervous System; Diltiazem belongs to Cardiovascular.
Why it happens
Diltiazem inhibits CYP3A4, which contributes to clozapine metabolism.
What to do
Monitor clozapine levels if available, along with sedation and blood pressure, and reduce the clozapine dose if toxicity develops.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
Other interactions of Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Frequently asked questions
Can I take Clozapine with Diltiazem?
MediHelp rates the interaction as moderate. Clozapine and Diltiazem can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Diltiazem may increase clozapine concentrations, raising the risk of sedation, seizures, hypotension and cardiac effects.
How serious is the interaction between Clozapine and Diltiazem?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor clozapine levels if available, along with sedation and blood pressure, and reduce the clozapine dose if toxicity develops.
What other medicines interact with Diltiazem?
MediHelp also lists interactions of Diltiazem with, for example, Flibanserin, Ivabradine, Lomitapide. The full list is on the Diltiazem page.
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