Which alpha-adrenergic blocking agent is used as reversal for xylazine?

• A. Tolazoline
• B. Yohimbine
• C. Naloxone
• D. Atipamezole

Answer: (B)

Xylazine produces its sedative and analgesic effects by stimulating alpha-2 adrenergic receptors, so reversing it means blocking those receptors with an alpha-2 antagonist. The agent that provides the most reliable, rapid, and predictable reversal is atipamezole, a highly selective alpha-2 antagonist. It counteracts the sedative and cardiovascular effects efficiently and with a favorable safety profile across species. Yohimbine can also antagonize alpha-2 receptors and has been used to reverse xylazine, but it is less selective and can cause more variable responses and additional side effects. Tolazoline is a non-selective alpha blocker and is not as precise for reversing xylazine, and naloxone targets opioids rather than alpha-adrenergic receptors. So the core idea is counteracting the alpha-2 stimulation with a selective antagonist, with atipamezole being the preferred reversal in modern practice.