Which opioid requires naloxone on hand due to high potency in wildlife immobilization?

• A. Etorphine
• B. Buprenorphine
• C. Diphenoxylate
• D. Carfentanil

Answer: (D)

Carfentanil is an ultra-potent mu-opioid agonist used specifically for immobilizing very large wildlife. Its potency is extraordinarily high—far greater than morphine and even much higher than etorphine—so even a minuscule amount can cause profound respiratory depression and life-threatening unconsciousness. Because of this extreme potency, having naloxone on hand to rapidly reverse opioid effects is essential during immobilization to restore breathing if overdose or oversedation occurs. Other options either have lower potency, act differently (such as partial agonists with ceiling effects), or are not used for wildlife immobilization, so they don’t carry the same immediate reversal risk.