Risk of immediate effects from F(ab)2 bivalent antivenin in Taiwan

To evaluate the incidence of immediate adverse effects from equine fragment antigen binding F(ab)2 bivalent antivenin produced by the National Institute of Preventive Medicine (NIPM) in Taiwan. A retrospective chart review of patients presenting to a 600-bed general hospital over a 3-year period with snakebite who were treated with NIPM antivenin. A total of 130 snakebite victims presented to the emergency department over the study period, and 159 vials of antivenin were given. One hundred two patients (78.5%; 95% CI: 70, 85) received only hemorrhagic bivalent antivenin, 2 (1.5%; 95% CI: 0, 5) received only neurotoxic bivalent antivenin, and the remaining 26 (20.0%; 95% CI: 13, 28) received both kinds of bivalent antivenin. Three received a second vial of hemorrhagic antivenin because of progression of symptoms. Fortytwo patients (32.3%; 95% CI: 24, 41) had positive skin tests, but following pretreatment with diphenhydramine and hydrocortisone, only 1 patient developed a skin rash thought to be related to antivenin. No patient developed an anaphylactic reaction. The use of NIPM F(ab)2 antivenin in snakebite victims in Taiwan has a very low risk of acute adverse reactions.