Green pit viper antivenom from Thailand and Agkistrodon halys antivenom from China compared in treating Cryptelytrops albolabris envenomation of mice

Objective To compare the relative efficacy of the green pit viper antivenom from Thailand and Agkistrodon halys antivenom from China. Design In-vivo experimental study. Setting A wildlife conservation organisation, a university, a poison information centre, and a regional hospital in Hong Kong. Main outcome measures Pre- and post-antivenom lethal dose 50 (LD ₅₀) of the Cryptelytrops albolabris venom, median effective dose (ED50) of green pit viper antivenom and Agkistrodon halys antivenom against a lethal dose of the venom. Subjects Adult mice. Results The intraperitoneal LD ₅₀ of the venom from locally caught Cryptelytrops albolabris was 0.14 μL. After post-exposure treatment with 10 μL of antivenom, it was elevated to 0.36 μL and 0.52 μL by the green pit viper antivenom and the Agkistrodon halys antivenom, respectively. The ED50 was 32.02 μL for green pit viper antivenom and 6.98 μL for Agkistrodon halys antivenom. Both green pit viper antivenom and Agkistrodon halys antivenom ameliorated the lethality of Cryptelytrops albolabris venom in mice. Conclusion The overall superior neutralisation capacity of Agkistrodon halys antivenom over green pit viper antivenom may be related to the geographic proximity of the venoms used for antivenom preparation. The results point towards the need for further comparison of the two antivenoms on protein or immunoglobulin weight basis, and with respect to non-lethal clinically significant toxicities.