Drug interactions
Donepezil + Phenobarbital
Severity: Moderate
Donepezil and Phenobarbital: 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
Phenobarbital is an enzyme inducer and may lower donepezil levels through increased CYP3A4 metabolism. Diminished effect on cognition can result with chronic coadministration.
What this interaction means in plain words
Donepezil and Phenobarbital 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.
Why it happens
Induction of CYP3A4 by phenobarbital accelerates donepezil metabolism.
What to do
Monitor cognitive and functional response; titrate donepezil if benefit wanes, and reassess if phenobarbital is stopped.
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 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 Donepezil with Phenobarbital?
MediHelp rates the interaction as moderate. Donepezil and Phenobarbital 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. Phenobarbital is an enzyme inducer and may lower donepezil levels through increased CYP3A4 metabolism. Diminished effect on cognition can result with chronic coadministration.
How serious is the interaction between Donepezil and Phenobarbital?
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 cognitive and functional response; titrate donepezil if benefit wanes, and reassess if phenobarbital is stopped.
What other medicines interact with Donepezil?
MediHelp also lists interactions of Donepezil with, for example, Dronedarone, Pimozide, Thioridazine. The full list is on the Donepezil page.
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