Etorphine is often used to immobilize elephants and other large mammals. Etorphine is available legally only for veterinary use and is strictly governed by law. Diprenorphine (M5050), also known as Revivon, is an opioid receptor antagonist that can be administered in proportion to the amount of etorphine used (1.3 times) to reverse its effects. Veterinary-strength etorphine is fatal to humans. For this reason the package as supplied to vets always includes the human antidote as well as Etorphine. The human antidote is generally naloxone, not diprenorphine, and is always prepared prior to the preparation of etorphine to be immediately administered following accidental human exposure to etorphine. One of its main advantages in general veterinary work is its speed of operation and, more importantly, the speed with which diprenorphine reverses the effects.
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