Which drug is an alpha-2 adrenergic agonist?

• A. Atropine
• B. Promazine
• C. Xylazine
• D. Diazepam

Answer: (C)

An alpha-2 adrenergic agonist works by stimulating alpha-2 receptors in the central nervous system, which dampens sympathetic outflow and produces sedation, analgesia, and sometimes bradycardia or hypotension. Xylazine is a classic veterinary drug that acts as an alpha-2 agonist, used as a sedative and analgesic in many species. That makes it the best fit for this question.

Atropine is an anticholinergic that blocks muscarinic receptors, not alpha-2 receptors. Promazine is a phenothiazine tranquilizer with dopamine receptor antagonism, not an alpha-2 agonist. Diazepam is a benzodiazepine that enhances GABA-A signaling, also not alpha-2. If needed, reversal of xylazine can be accomplished with an alpha-2 antagonist like atipamezole.