Initial experience with Crotalidae polyvalent immune Fab (ovine) antivenom in the treatment of copperhead snakebite.
OBJECTIVE
Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV) effectively treats patients bitten by rattlesnakes. The copperhead snake (Agkistrodon contortrix) caused 37% of venomous snakebites reported to US poison centers in 2001 and is the major envenomating reptile in the southeastern United States. FabAV has not been tested in human beings envenomated by copperhead snakes.


METHODS
In this preliminary study, we performed a retrospective chart review of all copperhead snake envenomations reported to the Carolinas Poison Center that were treated with FabAV. Progression of limb swelling, coagulopathy, and hemodynamic status before and after FabAV administration, adverse effects of FabAV therapy, and recurrence phenomena were recorded.


RESULTS
Of approximately 400 copperhead envenomation cases reported to the poison center during the study period, 32 received FabAV and were included. Most patients had moderate envenomation. The median time to FabAV administration was 4.0 hours. The median time to achieve initial control was 1.0 hour, with a median dose of 4 vials of FabAV. A rapid initial response, defined as cessation of the progression of local tissue injury within 4 hours of FabAV administration, occurred in 28 cases (88%; 95% confidence interval [CI] 76% to 99%). Four cases (13%; 95% CI 1% to 24%) were considered treatment failures. Recurrent swelling occurred in 6 cases (19%; 95% CI 5% to 32%). The incidence of recurrent swelling was not reduced by administration of repeated doses of antivenom on a planned schedule. One patient developed late-onset coagulopathy. One minor allergic reaction was observed.


CONCLUSIONS
In this select group of patients bitten by copperhead snakes, local tissue effects of envenomation halted promptly after FabAV treatment in most cases. Treatment failures occurred, and recurrence of swelling and defibrination syndrome was sometimes problematic. Time to return to work and long-term limb function were not assessed. A controlled trial with long-term follow-up is needed to define the role of FabAV treatment for copperhead envenomation.
Lavonas
Eric J
EJ
Division of Medical Toxicology, Department of Emergency Medicine, Carolinas Medical Center, Charlotte, NC 28232-2861, USA. eric.lavonas@carolinashealthcare.org
Gerardo
Charles J
CJ
O'Malley
Gerald
G
Arnold
Thomas C
TC
Bush
Sean P
SP
Banner
William
W
Steffens
Mark
M
Kerns
William P
WP
D000293:Adolescent; D000328:Adult; D000368:Aged; D017836:Agkistrodon; D000818:Animals; D000997:Antivenins / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003435:Crotalid Venoms; D005260:Female; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012189:Retrospective Studies; D012909:Snake Bites / Q000145:classification / Q000628:therapy*; D017211:Treatment Failure
D000997:Antivenins; D003435:Crotalid Venoms; C431183:Crotalidae Polyvalent immune Fab; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments