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Donepezil mechanism — MRCPsych Paper A MCQ

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EasyPsychopharmacologyDonepezil mechanismMRCPsych Paper A

A 79-year-old man with Alzheimer's disease is started on donepezil. His daughter asks how the drug may help cognition. What is the most likely mechanism of action?

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Correct answer: BInhibition of acetylcholinesterase

Donepezil is a specific, reversible acetylcholinesterase inhibitor. By reducing the enzymatic breakdown of acetylcholine, it increases cholinergic neurotransmission and can provide modest symptomatic benefit in cognition and functioning in Alzheimer's disease. It is not established as a disease-modifying treatment. NMDA receptor blockade describes a different antidementia mechanism associated with memantine, not donepezil. Dopamine D2 partial agonism is a mechanism of certain antipsychotics, while serotonin-reuptake inhibition is characteristic of SSRIs. Histamine H1 antagonism commonly produces sedation and does not account for donepezil's cognitive effects.

Reference: Electronic Medicines Compendium. ARICEPT 5 mg film-coated tablets: Summary of Product Characteristics, section 5.1 Pharmacodynamic properties. Updated 2023. https://www.medicines.org.uk/emc/product/3776/smpc