Crotalidae polyvalent immune Fab: in patients with North American crotaline envenomation

Abstract

Crotalidae polyvalent immune Fab is an antivenom comprising purified, sheep-derived, Fab IgG fragments and is indicated for use in patients with North American crotaline envenomation. Crotalidae polyvalent immune Fab is produced using four North American snake venoms: Crotalus atrox, Crotalus adamanteus, Crotalus scutulatus, and Agkistrodon piscivorus. Intravenous crotalidae polyvalent immune Fab was effective in patients aged ≥10 years who had minimal or moderate envenomation by a North American crotaline, who presented within 6 hours of the snakebite, and who had progression of the envenomation syndrome, according to the results of two prospective trials. One trial was a noncomparative, multicenter pilot study and the other trial was a randomized, open-label, multicenter trial in which patients received scheduled or 'as needed' administration of crotalidae polyvalent immune Fab after initial control had been achieved. A prospective, postmarketing trial demonstrated the efficacy of crotalidae polyvalent immune Fab in confirmed Crotalus viridis helleri envenomation (indicating cross-protection against a venom not used in its production). Results of these prospective trials are supported by the findings of additional (mainly retrospective) studies demonstrating the efficacy of crotalidae polyvalent immune Fab in patients with crotaline envenomation, including patients with severe envenomation, pediatric patients, and patients with symptoms of neurotoxicity. Despite treatment with crotalidae polyvalent immune Fab, patients may experience delayed-onset or recurrent venom effects (e.g. coagulopathy). Intravenous crotalidae polyvalent immune Fab was generally well tolerated; acute hypersensitivity reactions (e.g. urticaria, rash, pruritus) were the most commonly occurring adverse event.