Drug interactions
Memantine-donepezil + Phenobarbital
Severity: Minor
Memantine-donepezil and Phenobarbital: minor 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 plasma concentrations of donepezil, the cholinesterase inhibitor component of this combination product. This may reduce the cognitive benefit of treatment, although the clinical impact is generally modest. Phenobarbital also adds to central nervous system depression and sedation.
What this interaction means in plain words
Memantine-donepezil and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Phenobarbital induces CYP3A4 (and CYP2D6-mediated pathways to a lesser extent), increasing donepezil clearance.
What to do
Monitor cognitive and functional response when phenobarbital is started or stopped, and consider a donepezil dose adjustment if benefit appears to fade. Watch for excess sedation.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Memantine-donepezil
- Dronedarone + Memantine-donepezil Contraindicated
- Memantine-donepezil + Thioridazine Contraindicated
- Amantadine + Memantine-donepezil Major
- Amiodarone + Memantine-donepezil Major
- Amisulpride + Memantine-donepezil Major
- Amitriptyline + Memantine-donepezil Major
Frequently asked questions
Can I take Memantine-donepezil with Phenobarbital?
MediHelp rates the interaction as minor. Memantine-donepezil and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenobarbital is an enzyme inducer and may lower plasma concentrations of donepezil, the cholinesterase inhibitor component of this combination product. This may reduce the cognitive benefit of treatment, although the clinical impact is generally modest. Phenobarbital also adds to central nervous system depression and sedation.
How serious is the interaction between Memantine-donepezil and Phenobarbital?
MediHelp rates it minor, 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 when phenobarbital is started or stopped, and consider a donepezil dose adjustment if benefit appears to fade. Watch for excess sedation.
What other medicines interact with Memantine-donepezil?
MediHelp also lists interactions of Memantine-donepezil with, for example, Dronedarone, Thioridazine, Amantadine. The full list is on the Memantine-donepezil page.
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