Tuesday May 11, 2021

Rattlesnakes, copperheads, cottonmouths, oh my! The antivenins for crotalid envenomation

Summertime means snakebite time, and with it comes the critical decisions pharmacists and clinicians are faced with when choosing antivenins. In this episode, we will look at the differences and similarities between the two latest antivenins for snakebites.


Guest speaker:

Philippe Mentler, PharmD, BCPS

Consulting Director, Pharmacy




Gretchen Brummel, PharmD, BCPS

Pharmacy Executive Director

Vizient Center for Pharmacy Practice Excellence


Show Notes:

[00:54] A quarter of all snakebites are dry bites

[01:24] Venomous snakes are everywhere in the United States except in Alaska and Hawaii

[01:24] Most common venomous snakes in North America are pit vipers (rattlesnakes, copperheads, cottonmouths)

[02:00] Clinical manifestations of snakebites

[02:40] In 2019, American poison control reported more than 4,000 pit viper snakebites

[02:55] History of antivenins

[03:50] The development of a new antivenin, CroFab

[04:55] In 2019, FDA approved Anavip for North American Rattlesnakes, and in April 2021 FDA updated its approval for all North American pit vipers

[05:26] Variances between antivenins Anavip and CroFab

[06:13] Clinical trials focusing on blood dyscrasias for Anavip and CroFab

[07:15] The original approval for Anavip was exclusively in rattlesnakes and did not consider copperheads and cottonmouths because of the limited incidence of blood dyscrasias in those species in the trial

[07:58] Cottonmouths and copperheads typically don’t cause blood dyscrasias and tissue injury. This was not specifically addressed in the original study. Now, Anavip updated their information to the FDA, and with that the FDA approved antivenin for all pit viper snakes

[08:45] Should a hospital carry both products?  

[09:25] There’s no national guidelines for antivenins. The American Academy of Emergency Medicine published a clinical statement about antivenin drugs, but that’s obsolete now that the FDA has updated its antivenin approval


Links | Resources:

ANAVIP, crotalidae immune F(ab)2 (Equine): Click here

CroFab crotalidae polyvalent immune fab (ovine): Click here

American Association of Poison Control Centers: National Poison Data System Click here

NCBI: Rattle Snake Toxicity Click here

USDA, Forest Service: “Snakes” Click here

Centers for Disease Control and Prevention, The National Institute for Occupational Safety and Health: “Venomous Snakes” Click here

Alaska Department of Fish and Game: “No snakes in Alaska” Click here


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