Crotalidae Polyvalent immune Fab

Description

Crotalidae Polyvalent Immune Fab (ovine) was launched as CroFab? in the US for the treatment of North American crotalid snake envenomation. It is the second antivenom to be commercialized over fifty years after Antivenin (Crotalidae) Polyvalent (equine) from Wyeth Labs. CroFab? is prepared by purification of Fab immunoglobulin fragments obtained from the blood of healthy sheep flocks immunized with one of the following North American snake venoms: Crotalus atrox (Western Diamondback rattlesnake), Crotalus adamanteus (Eastern Diamondback rattlesnake), Crotalus scutulatus (Mojave rattlesnake), and Agkistrodon piscivorus (Cottonmouth or Water Moccasin). The final preparation is achieved by mixing the four different monospecific antivenins after fractionating the immunoglobulin G from the ovine serum, cleaving the whole antibody into Fab and Fc fragments with papain and isolating each of the venom-specific Fab fragments on ion exchange and affinity chromatography columns. CroFab? acts by binding and neutralizing venom toxins, facilitating their redistribution away from target tissues and their elimination from the body. In infected mice, CroFab? was found to be 3-9 times more potent than Antivenin (Crotalidae) Polyvalent (equine) for the prevention of lethality of nine venoms. In a randomized clinical trial, initial control of envenomation was achieved in all patients treated with intravenous administrations of CroFab?. The risk of hypersensitivity is decreased with this mixture of specific antivenins compared to Antivenin (Crotalidae) Polyvalent (equine) due to the absence of the Fc components of the immunoglobulin. The elimination half-life of CroFab? ranged from approximately 12 to 23 hours, which is relatively short for an antibody.

Originator

Protherics (UK)

brand name

CroFab

Veterinary Drugs and Treatments

The equine-derived product is indicated for the treatment of envenomation from most venomous snake bites (pit vipers) in North America and those caused by several species found in Central and South America (fer-de-lance, Central and South American Rattlesnake). The ovine-derived product is indicated for North American Crotalid snake envenomation in humans, but has been used in dogs. There is a fair amount of controversy with regard to use of these products in domestic animals. The risks of administration (e.g., anaphylaxis— see below) may outweigh their potential benefits in certain circumstances. However, these agents can be life saving when given early in select situations. Many factors contribute to the potential for toxicity (victim’s size and general health, bite site(s), number of bites, age, species and size of snake, etc.).

Raw materials

Preparation Products