Disulfiram Mechanism — MRCPsych Paper B MCQ

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EasySubstance MisuseDisulfiram MechanismMRCPsych Paper B

A 50-year-old man with alcohol dependence is prescribed disulfiram as part of a relapse-prevention plan. Which mechanism accounts for its alcohol-deterrent effect?

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Correct answer: E — Irreversible inhibition of aldehyde dehydrogenase

Disulfiram irreversibly inhibits hepatic aldehyde dehydrogenase. If ethanol is consumed, its metabolite acetaldehyde accumulates and produces an aversive disulfiram–alcohol reaction, which may include flushing, nausea, vomiting, headache, palpitations, tachycardia and hypotension. This deterrent effect supports abstinence rather than directly reducing craving. Opioid-receptor antagonism describes naltrexone, not disulfiram. Disulfiram does not exert its therapeutic effect through GABA-A receptor antagonism or partial agonism, and it does not reduce the gastrointestinal absorption of ethanol. The UK SmPC directly identifies irreversible aldehyde dehydrogenase inhibition as its primary mechanism.

Reference: Brown & Burk UK Ltd. Disulfiram 200 mg tablets: Summary of Product Characteristics, sections 4.8 and 5.1. Revised 7 October 2025; updated on eMC 17 October 2025. https://www.medicines.org.uk/emc/product/11168/smpc