A 40-year-old man who smokes 20 cigarettes daily wants to quit. He is started on a drug that acts as a partial agonist at the alpha-4 beta-2 nicotinic receptor, reducing both craving and the reward from smoking. Which drug was prescribed?
- A Varenicline ✓
- B Bupropion
- C Nortriptyline
- D Clonidine
Correct answer: A. Varenicline
Explanation
Varenicline is a partial agonist at alpha-4 beta-2 neuronal nicotinic acetylcholine receptors. Partial agonism gives enough receptor stimulation to reduce craving and withdrawal while blocking full nicotine-induced dopamine release in the nucleus accumbens, blunting reward. Bupropion works mainly through dopamine and norepinephrine reuptake inhibition without direct nicotinic receptor activity, which distinguishes it from varenicline.
Reference: Kaplan and Sadock's Synopsis of Psychiatry, 12th ed.
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