Therese Lindberg

therese.lindberg@cambio.se

Cambio CDS

Doses antivenom (CroFab only, not Anavip) for pit viper snakebites.

This dosing tool is intended to assist with calculation, not to provide comprehensive or definitive drug information. Always double-check dosing of any drug and consult a pharmacist when necessary. Use only in cases of symptomatic crotalid snake envenomation (pit vipers including rattlesnakes, cottonmouths, and copperheads) in the US, for CroFab administration. Algorithm, as follows: 1. Are there signs of envenomation? Signs include: Swelling, tenderness, redness, ecchymosis, or blebs at bite site. Elevated protime, decreased fibrinogen or platelets. Systemic signs (hypotension, bleeding beyond puncture site, refractory vomiting, diarrhea, angioedema, neurotoxicity). If YES, proceed to 2. If NO, this is an apparent dry bite or no bite. Observe patient ≥8 hours, repeat labs prior to discharge, and do not administer antivenom. Check for indications for antivenom: 2. Check for indications for antivenom: Swelling that is more than minimal and is progressing. Elevated protime, decreased fibrinogen or platelets. Any systemic signs. If YES, proceed to 3. If NO, this is an apparent minor envenomation. Observe patient 12-24 hours, repeat labs at 4-6 hrs and prior to discharge, and do not administer antivenom. 3. Administer antivenom: Establish IV access, give IV fluids. Mix 4-6 vials of crotaline Fab antivenom in 250 mL NS and infuse over 1 hour. Increase dose to 6-8 vials for patients in shock or with serious active bleeding. Reexamine after 1 hour, and proceed to 4. 4.Check for control of envenomation (after initial antivenom): Swelling and tenderness not progressing. Protime, fibrinogen, platelets normal or clearly improving. Clinically stable. Neurotoxicity resolved or clearly improving. If YES, monitor patient and perform serial examinations and maintenance therapy (2 vials of antivenom every 6 hours x 3 doses (given 6, 12, and 18 hours after initial control). Maintenance therapy may not be needed if close observation by physician expert is available. If NO, then repeat antivenom until control is achieved.

Do not use to provide comprehensive or definitive drug information. Do not use in cases of coral snake envenomation or snakes not indigenous to the US. Do not use for Anavip administration, as it will result in incorrect dosing. Report all cases of suspected/confirmed envenomation to poison control (1-800-222-1222).

1. Lavonas EJ, Ruha AM, Banner W, et al. Unified treatment algorithm for the management of crotaline snakebite in the United States: results of an evidence-informed consensus workshop. BMC Emerg Med. 2011;11:2. 2. Hoffman R, Howland MA, Lewin N et al. Goldfrank's Toxicologic Emergencies, Tenth Edition. McGraw-Hill Education / Medical; 2014.

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