History of North American Crotalid Snakebite Antidotes 

Antivenin Crotalidae Polyvalent (Wyeth-Ayerst Laboratories, Inc.) was the first modern snakebite treatment. It was manufactured from horse serum and contained protective substances capable of neutralizing the toxic effects of venoms of crotalids (pit vipers) including rattlesnakes, copperhead and cottonmouth moccasins. It was available beginning in the early 1950s. Wyeth has since discontinued production of this antivenom.

In October 2000, the first new snakebite treatment in 50 years was approved. CroFab^® Crotalidae Polyvalent Immune Fab (Ovine) is indicated for the management of patients with minimal or moderate North American crotalid envenomation.  The term crotalid is used to describe the Crotalinae subfamily (formerly known as Crotalidae) of venomous snakes, which includes rattlesnakes, copperheads and cottonmouths/water moccasins.  Early use of CroFab^® (within 6 hours of snakebite) is advised to prevent clinical deterioration and the occurrence of systemic coagulation abnormalities.

The most common adverse events reported in clinical studies were mild or moderate reactions involving the skin and appendages (primarily urticaria, rash or pruritus), which occurred in 14 out of 42 patients.  Three patients experienced a serious adverse event.  Two patients had a severe allergic reaction (severe hives and a severe rash and pruritus) following treatment.  One patient had a recurrent coagulopathy due to envenomation, which required re-hospitalization and additional antivenin administration. In clinical trials, recurrent coagulopathy (the return of a coagulation abnormality after it has been successfully treated with antivenin), characterized by decreased fibrinogen, decreased platelets and elevated prothrombin time, occurred in approximately half of the patients studied. Recurrent coagulopathy may persist for one to two weeks or more.  One patient discontinued CroFab^® therapy due to an allergic reaction.  Patients with allergies to papain, chymopapain, other papaya extracts or the pineapple enzyme bromelain may also be at risk for an allergic reaction to CroFab^®.

Please click on the CroFab^® full prescribing information link at left for complete prescribing information, including events, precautions or warnings.

© CroFab^® is manufactured by/registered trademarks of Protherics US Inc., Brentwood, TN  37027 and distributed by Savage Laboratories^®