What is CroFab®

CroFab® Heritage

History of antivenom

Prior to the introduction of CroFab® Crotalidae Polyvalent Immune Fab (Ovine), antivenin therapy consisted of a whole immunoglobulin product. The presence of the Fc receptor resulted in significant rates of acute reactions and delayed serum sickness.

Introduction of CroFab®

Approved in 2000, CroFab® was designed to reduce the high incidence of hypersensitivity that occurred with previous antivenom therapy. In the years since, CroFab® has demonstrated a low incidence of hypersensitivity reactions and serum sickness (8% [95% CI = 5% to 11%] and 13% [95% CI = 7% to 21%], respectively), and has become the antivenom that healthcare professionals rely on for the treatment of North American pit viper envenomation.

Mechanism of action

CroFab® consists of venom-specific Fab fragments of immunoglobulin G (IgG) that work by binding to and neutralizing venom toxins, facilitating their redistribution away from target tissues and their elimination from the body.

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  1. CroFab® contains only the Fab fragments from ovine-derived immunoglobulins.
  2. The enzyme papain is used to cleave the IgG antibody, creating 2 separate Fab fragments and 1 Fc fragment.
  3. After cleavage, another protein binds the Fc fragments, which are not necessary for binding snake venom, allowing the pure Fab fragments to be recovered.
  4. The Fab fragments of an immunoglobulin contain the variable regions that recognize and bind to specific antigens.
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