What is the pharmacologic action of disulfiram when alcohol is consumed?

• A. Inhibits acetaldehyde production completely
• B. Blocks dopamine receptors in the brain
• C. Causes a rapid rise in acetaldehyde
• D. Increases the metabolism of alcohol to acetate quickly

Answer: (C)

Disulfiram works by inhibiting the enzyme aldehyde dehydrogenase. When alcohol is consumed, ethanol is metabolized to acetaldehyde, which is normally converted to acetate by aldehyde dehydrogenase. Blocking that step causes acetaldehyde to accumulate rapidly, producing an unpleasant reaction (flushing, rapid heart rate, nausea, headache, sometimes faintness or vomiting). This aversive response discourages drinking. The action is not to stop acetaldehyde from forming, nor to affect dopamine receptors, nor to speed up the conversion of alcohol to acetate; it actually slows the clearance of acetaldehyde, leading to its rapid buildup after alcohol intake.