Repeat antivenom administration following crotalidae immune F(ab')2 antivenom in Agkistrodon species: a case series.

Crotalidae immune F(ab')2 [equine] was approved for the treatment of North American rattlesnake envenomation in 2015 and Agkistrodon envenomation in 2021 after a phase 3 trial demonstrated lower rates of late hemotoxicity compared to crotalidae polyvalent immune fab-ovine (Fab) in a population of primarily rattlesnake envenomations. Currently, there are limited data on the use of this new antivenom in controlling tissue damage associated with Agkistrodon envenomations. We describe four cases of Agkistrodon contortrix envenomation in which edema continued to progress despite standard doses of F(ab')2, necessitating administration of additional antivenom. In three cases, control was achieved only after a switch to Fab. As F(ab')2 use in envenomations by the primarily cytotoxic Agkistrodons increases, further research is needed to evaluate its ability to control tissue damage. [ABSTRACT FROM AUTHOR]