Acamprosate — MRCPsych Paper B MCQ

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ModerateSubstance MisuseAcamprosateMRCPsych Paper B

Following successful assisted withdrawal, a patient with alcohol dependence is prescribed medication to help maintain abstinence. Its pharmacodynamic effects are thought to include enhancement of GABAergic inhibitory neurotransmission and antagonism of excitatory amino-acid neurotransmission, particularly glutamate. Which medication is this?

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Correct answer: A — Acamprosate

Acamprosate is correct. It is used after alcohol withdrawal to support continued abstinence, alongside psychosocial treatment. The UK SmPC states that it may enhance GABAergic inhibitory neurotransmission and antagonise excitatory amino-acid neurotransmission, particularly glutamate; it is also commonly characterised as modulating NMDA-related transmission, although its precise molecular mechanism is not fully established. Naltrexone is an opioid-receptor antagonist that reduces alcohol-related reinforcement rather than acting through this glutamate–GABA mechanism. Disulfiram irreversibly inhibits aldehyde dehydrogenase, producing acetaldehyde accumulation if alcohol is consumed. Methadone is a full mu-opioid agonist, while buprenorphine is a partial mu-opioid agonist; both are principally used in opioid dependence. The clinical timing and pharmacodynamic description therefore uniquely identify acamprosate.

Reference: electronic Medicines Compendium, Acamprosate 333 mg Gastro-resistant Tablets, SmPC sections 4.1 and 5.1, revised November 2025. https://www.medicines.org.uk/emc/product/2729/smpc