Drug interactions
Diltiazem + Donepezil
Severity: Moderate
Diltiazem and Donepezil: 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 raise donepezil concentrations, increasing cholinergic effects such as nausea, bradycardia and syncope. Both drugs can slow heart rate.
What this interaction means in plain words
Diltiazem and Donepezil 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 belongs to Cardiovascular; Donepezil belongs to Central Nervous System.
Why it happens
Diltiazem inhibits CYP3A4 metabolism of donepezil, with additive bradycardic effects.
What to do
Monitor heart rate and for gastrointestinal or cholinergic effects, and reduce the donepezil dose if bradycardia or intolerance occurs.
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 Donepezil
- Donepezil + Dronedarone Contraindicated
- Donepezil + Pimozide Contraindicated
- Donepezil + Thioridazine Contraindicated
- Donepezil + Vandetanib Contraindicated
- Amiodarone + Donepezil Major
- Amisulpride + Donepezil Major
Frequently asked questions
Can I take Diltiazem with Donepezil?
MediHelp rates the interaction as moderate. Diltiazem and Donepezil 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 raise donepezil concentrations, increasing cholinergic effects such as nausea, bradycardia and syncope. Both drugs can slow heart rate.
How serious is the interaction between Diltiazem and Donepezil?
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 heart rate and for gastrointestinal or cholinergic effects, and reduce the donepezil dose if bradycardia or intolerance occurs.
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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