Which medication blocks opioid receptors to reduce the rewarding effects of alcohol?

• A. Naltrexone
• B. Acamprosate
• C. Disulfiram
• D. Methadone

Answer: (A)

Blocking the brain’s opioid receptors reduces the rewarding effects of alcohol. Naltrexone is an opioid receptor antagonist, especially at mu receptors, which dampens the dopamine surge in the mesolimbic pathway that alcohol normally triggers. By preventing this rewarding signaling, it lowers craving and helps prevent relapse after someone begins abstinence or reduces drinking.

Other medications work through different mechanisms. Acamprosate helps normalize glutamate activity to support abstinence and withdrawal management, but it doesn’t block opioid receptors. Disulfiram creates an unpleasant reaction if alcohol is ingested by inhibiting aldehyde dehydrogenase, not by receptor blockade. Methadone is an opioid agonist used for opioid use disorder, not for blunting alcohol’s rewarding effects.

Clinical note: Naltrexone is typically used after a period of abstinence or withdrawal from opioids (to avoid precipitated withdrawal) and requires monitoring of liver function. It should not be used in someone currently dependent on opioids or without appropriate screening.