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Disulfiram reaction — MRCPsych Paper A MCQ

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ModeratePsychopharmacologyDisulfiram reactionMRCPsych Paper A

A 44-year-old man with alcohol dependence is started on a relapse-prevention medication. He is specifically warned that drinking alcohol while taking it can cause a potentially dangerous reaction. After drinking wine, he rapidly develops flushing, throbbing headache, nausea and palpitations. Which pharmacological action primarily accounts for this reaction?

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Correct answer: A — Inhibition of aldehyde dehydrogenase

The correct answer is A. This is a disulfiram–alcohol reaction. Disulfiram irreversibly inhibits hepatic aldehyde dehydrogenase, preventing the normal conversion of acetaldehyde to acetate. Alcohol consumption therefore causes acetaldehyde accumulation, producing vasodilation and autonomic symptoms such as flushing, throbbing headache, nausea, palpitations and, in severe cases, hypotension or cardiovascular collapse. Mu-opioid receptor antagonism is the principal action of naltrexone. GABA-B receptor agonism describes baclofen, while modulation of glutamatergic neurotransmission is associated with acamprosate. Dopamine D2 receptor blockade is characteristic of many antipsychotic drugs and does not explain this alcohol-triggered reaction.

Reference: Brown & Burk UK Ltd. Disulfiram 200 mg tablets: Summary of Product Characteristics, sections 4.8 and 5.1. Updated 17 October 2025. https://www.medicines.org.uk/emc/product/11168/smpc