Use of Crotalidae equine immune F(ab’)₂ antivenom for treatment of an Agkistrodon envenomation

Introduction: Anavip (F(ab’)₂AV) is a lyophilized F(ab’)₂ immunoglobulin fragment derived from horses immunized with venom from Bothrops asper and Crotalus durissus. It was approved by the FDA in 2015 for treatment of North American rattlesnake envenomation but not for Agkistrodon envenomation. Published data regarding the efficacy and safety of Anavip in treating Agkistrodon envenomations is limited. We present a case of a patient treated with Anavip after confirmed Agkistrodon laticinctus envenomation. Case details: A 77 year-old man was bitten on his fifth finger by a captive A. laticinctus. He was taken to a local emergency department where he received a 10 vial initial dose of F(ab’)₂AV for pain and swelling and was transferred. At the receiving facility, his pain had improved and his swelling had not progressed. Over the next 30 h, his platelets declined to 132,000/mm³ and he received an additional 4 vials of F(ab’)₂AV. The remainder of his course was unremarkable with complete recovery by 3 months. Discussion: This case provides an additional published datapoint on the use of this F(ab’)₂AV in the treatment of envenomation by Agkistrodon.