Anavip (crotalidae immune F(ab’)2 [equine]) has been made available by Rare Disease Therapeutics for the management of adult and pediatric patients with North American rattlesnake envenomation.

While treatment with antivenom during the acute phase of pit viper envenomation may correct potential coagulation disorders such as hypofibrinogenemia and thrombocytopenia, there have been reports of delayed coagulopathy that could potentially result in hemorrhage or death. Anavip contains venom-specific F(ab’)2 fragments of immunoglobulin G (IgG) that bind and neutralize venom toxins, facilitating redistribution away from target tissues and elimination from the body. Because the treatment has a long half-life, it reduces the likelihood of coagulopathic effects, and eliminates the need for additional doses commonly required with shorter-acting antivenom.

Related Articles

“From our experience as participants in the clinical trials for Anavip, it appears that this new antivenom works very well to reverse the symptoms associated with acute rattlesnake bite, and may have less issues with symptom recurrence than the presently approved antivenom,” said Richard Clark, MD, Director of Medical Toxicology at UCSD Medical Center and Medical Director of the San Diego Division of the California Poison Control System.

Anavip is supplied as a sterile lyophilized preparation in single-use vials. When reconstituted with 10mL of 0.9% NaCl solution, each vial contains not more than 12mg per mL of protein, and will neutralize not less 780 times the LD50 of Bothrops asper venom and 790 times the LD50 of Crotalus durissus venom in a mouse neutralization assay. Treatment should be administered as soon as possible after rattlesnake bite in patients who develop any signs of envenomation.

For more information visit