disulfiram-like reaction
Summary
A disulfiram-like reaction occurs when certain medications inhibit aldehyde dehydrogenase, causing acetaldehyde accumulation upon alcohol ingestion. This leads to flushing, headache, nausea, vomiting, tachycardia, and hypotension. It mimics the reaction seen with disulfiram, a drug used to deter alcohol consumption in alcohol use disorder.
Detail
Mechanism: Alcohol metabolism normally proceeds via alcohol dehydrogenase (ethanol → acetaldehyde) and aldehyde dehydrogenase (acetaldehyde → acetate). Disulfiram and disulfiram-like drugs inhibit aldehyde dehydrogenase, causing toxic acetaldehyde accumulation when alcohol is consumed. This produces an unpleasant reaction: facial flushing, throbbing headache, nausea, vomiting, palpitations, tachycardia, hypotension, and diaphoresis—symptoms that discourage further alcohol use.
Classic drugs causing disulfiram-like reactions (high-yield for boards, mnemonic 'MCG PT' or similar): - Metronidazole (very commonly tested) - Certain cephalosporins (especially those with methylthiotetrazole side chain: cefotetan, cefamandole, cefoperazone) - Griseofulvin - Sulfonylureas (particularly chlorpropamide, first-generation) - Procarbazine - Trimethoprim-sulfamethoxazole (some sources)
Clinical significance: Patients prescribed these medications should be counseled to avoid alcohol during treatment and for a period afterward (e.g., avoid alcohol for at least 3 days after metronidazole, up to 2 weeks after disulfiram itself due to irreversible enzyme inhibition requiring new enzyme synthesis).
Disulfiram itself is used therapeutically as aversion therapy for alcohol use disorder—patients experience this unpleasant reaction if they drink alcohol while on the medication, reinforcing abstinence.
Differentiate from other alcohol-related reactions: unlike direct alcohol toxicity, the disulfiram-like reaction is specifically due to acetaldehyde buildup, not ethanol itself.
Sources
- Katzung's Basic & Clinical Pharmacology
- First Aid for the USMLE Step 1
- Goodman & Gilman's The Pharmacological Basis of Therapeutics
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