Carfentanil

Carfentanil or Carfentanyl (R33799) is an analogue of the popular synthetic morphine and 100 times that of fentanyl, activity in humans starting at about 1 μg. It is marketed under the trade name Wildnil as a tranquilizer for large animals.^[1] Carfentanil is intended for animal use only as its extreme potency makes it inappropriate for use in humans.

A good practical example of the drug in use in veterinary practice was shown in an episode of the Discovery Channel series, Animal Cops: Houston, where carfentanil was administered orally (dissolved in honey, specifically) to a full-grown brown bear to tranquilize it so that it could be safely relocated to the Houston Zoo from a south Texas animal abuser's property. A few tablespoons' worth of the anesthetic was sufficient to put the grizzly bear, weighing more than 1000 pounds, to sleep.

Moscow theater hostage crisis

It is thought that in the 2002 Moscow theater hostage crisis, the Russian military made use of an aerosol form of either carfentanil or another similar drug such as naltrexone (opioid antagonists) to prevent complications in many of the victims. Assuming that carfentanil was the only active constituent (which has not been verified by the Russian military), the primary acute toxic effect to the theatre victims would have been opioid-induced apnea; in this case mechanical ventilation and/or treatment with opioid antagonists would have been life-saving for many or all victims.

References

1. ^ De Vos V., Immobilisation of free-ranging wild animals using a new drug, Vet Rec. 1978 July 22;103(4):64-8
2. ^ Wax PM, Becker CE, Curry SC. Unexpected "gas" casualties in Moscow: a medical toxicology perspective. Ann Emerg Med 2003;41:700-5. PMID 12712038