Acamprosate mechanism — MRCPsych Paper A MCQ

Instant feedback + full explanation. One question, done properly.

ModeratePsychopharmacologyAcamprosate mechanismMRCPsych Paper A

A 48-year-old man with alcohol dependence has completed assisted withdrawal and remains abstinent. Acamprosate is started alongside psychosocial treatment to help maintain abstinence. Which pharmacodynamic action most likely contributes to its therapeutic effect?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Modulation of glutamatergic neurotransmission

Acamprosate most likely acts by modulating glutamatergic neurotransmission, helping correct the disturbed balance between excitatory glutamate and inhibitory GABA signalling that follows chronic alcohol exposure and withdrawal. Its precise molecular mechanism remains incompletely established, so broad glutamatergic modulation is more defensible than describing it as a simple direct NMDA antagonist. Mu-opioid receptor antagonism is associated with naltrexone, whereas inhibition of aldehyde dehydrogenase is the aversive mechanism of disulfiram. Serotonin-reuptake inhibition characterises SSRIs, and dopamine D2 receptor blockade characterises most antipsychotics. Acamprosate is used after withdrawal to maintain abstinence and should be combined with psychosocial treatment.

Reference: Electronic Medicines Compendium. Acamprosate 333 mg Gastro-resistant Tablets, Summary of Product Characteristics, section 5.1 Pharmacodynamic properties. Updated 2025. https://www.medicines.org.uk/emc/product/2729/smpc