• J R Brubacher, D Lachmanen, and R S Hoffman.
• Department of Emergency Medicine Vancouver Hospital, British Columbia, Canada.
• Wilderness Environ Med. 1999 Jan 1;10(3):142-5.

ObjectivesWyeth polyvalent crotalid antivenin is the only commercial antivenin available in the United States to treat North American crotalid envenomations. Wyeth antivenin is made from the serum of horses hyperimmunized with four crotalid venoms (Crotalus adamanteus, Crotalus atrox, Crotalus durrisus terrificus, and Bothrops atrox). Although Wyeth antivenin is believed to be effective against all North American crotalids, its efficacy against Agkistrodon contortrix (copperhead) has never been tested. The purpose of this experiment was to determine the efficacy of Wyeth antivenin in the treatment of copperhead envenomation.MethodsWyeth antivenin was reconstituted in 10 mL of sterile water. In preliminary experiments, 20 mL/kg of Wyeth antivenin administered intraperitoneally prevented death in mice given a lethal subcutaneous injection of Crotalus adamanteus venom. Freeze-dried copperhead venom was reconstituted in sterile water, and a dose-lethality curve for subcutaneous venom was constructed using seven groups of 10 mice each. The endpoint was survival at 24 hours. A dose that is lethal in 90% of the animals receiving it (LD90) was estimated from this curve. Thirty mice were randomly given pretreatment with 20 mL/kg Wyeth antivenin administered intraperitoneally or an equal volume of normal saline as a control. Thirty minutes later, all mice received an LD90 subcutaneous injection of copperhead venom. Lethality was determined at 24 hours.ResultsFollowing the injection of copperhead venom, none of the 15 control mice and 14 of 15 treatment mice survived until 24 hours (p < 0.001).ConclusionWyeth antivenin is effective in treating copperhead envenomation in mice and may therefore be expected to be effective in humans.

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