Australian Tiger Snake (Notechis scutatus) and Mexican Coral Snake (Micruris species) Antivenoms Prevent Death from United States Coral Snake (Micrurus fulvius fulvius) Venom in a Mouse Model

Abstract

Background: Wyeth-Ayerst has discontinued production of Antivenin (Micrurus fulvius). Currently, there is no other approved coral snake antivenom available in the United States. Methods: This study was a randomized, placebo-controlled and blinded determination of the ability of a Mexican Micrurus (coral snake) antivenom and an Australian Notechis (tiger snake) antivenom to prevent lethality from a United States Micrurus fulvius fulvius venom in a mouse model. Venom dosing was based on an LD₅₀ determined for this experiment. Our comparison groups included: (1) M. f. fulvius venom+Micrurus antivenom, (2) M. f. fulvius venom+Notechis antivenom, (3) M. f. fulvius venom+protein control, (4) 0.9% normal saline+protein control, (5) saline+Notechis antivenom, (6) saline+Micrurus antivenom. Venom dose was 5 times the determined LD₅₀. The antivenom amounts were capable of neutralizing 10 times the venom injected (50 times the LD₅₀). Results: The LD₅₀ of M. f. fulvius venom was determined to be 0.85 mg/kg. All mice in both antivenom test groups were protected from lethality for the entire 24-hour observation period. Six of the 7 mice in the venom test group died, with a survival time of 349±382 minutes (mean±s.d.) after the venom injection. All three groups of control mice survived the entire 24-hour observation period. Conclusions: Mexican Micrurus antivenom and Australian Notechis antivenom provide protection from lethality in mice envenomated with a United States M. f. fulvius venom.