Dosing and Administration

Appropriate Dosing of CroFab® Achieves Initial and Sustained Control of Envenomation1

CroFab® should be administered as soon as possible in patients with any sign of envenomation (e.g., local, systemic, or hematologic effects) to prevent clinical deterioration.

Vial imagery
  • Administer an initial dose of 4-6 vials* and monitor for signs of progression
  • Administer an additional 4-6 vials if initial control is not achieved ~1 hr after initial dose
  • Once initial control is achieved, administer an additional 2 vials every 6 hr for up to 18 hr (total of 3 doses)
  • Scheduled maintenance dosing reduced the incidence of coagulation abnormalities due to residual venom

In pre- and postmarketing studies, 67-88% of patients achieved initial control with an initial dose of 4-6 vials when given according to recommended dosing.2,3

*Initial dose may vary from 4-12 vials based on clinical judgment and severity of envenomation. Dosing is the same in adult and pediatric patients.

Check for Signs of Initial Control

Signs of initial control include1:

  • Halting of the progression of local effects, such as edema and ecchymosis
  • A clear trend toward improvement in coagulation abnormalities, such as thrombocytopenia and spontaneous bleeding
  • Resolution of all systemic effects, such as nausea, vomiting, dizziness, or tachycardia

Efficacy determined using the snakebite severity score (SSS), a validated objective tool for the clinical evaluation of North American pit viper snakebite in adults. The total score reflects patient evaluation on 6 dimensions: cardiovascular system, local wound, gastrointestinal system, hematologic symptoms, pulmonary system, and central nervous system. The higher the total score, the more severe the snakebite.1

Watch Dr. William Banner discuss his approach to dosing antivenom for children.

Administering CroFab® to Achieve Control1:

  • Establish IV access and give IV fluids
  • Initiate first dose of CroFab® in ED or ICU
  • Mix 4-6 vials of CroFab® in 250 mL normal saline (0.9% sodium chloride)
  • Infuse over 60 minutes, proceeding slowly over the first 10 minutes at a 25- to 50-mL/hour rate with careful observation for any allergic reaction
  • If no allergic reaction occurs, increase infusion rate to the full 250 mL/hour until completion
  • Close patient monitoring is necessary
  • Postmarketing data showed low rates of hypersensitivity reactions (1.4% and 2.7%) in two studies including 1340 and 373 patients, respectively4,5
  • For patients in shock or with serious active bleeding, call physician-expert
  • For suspected adverse reaction: Hold infusion, treat accordingly, and call physician-expert
  • Re-examine patient for treatment response within 1 hour of completion of CroFab® infusion

Initial dose may vary from a minimum of 4 to a maximum of 12 vials based on clinical judgment and severity of envenomation.

Watch a video on the reconstitution process for CroFab®.


1. CroFab® [prescribing Information]. BTG International Inc; January 2018. 2. Dart RC, Seifert SA, Boyer LV, et al. A randomized multicenter trial of crotalinae polyvalent immune Fab (ovine) antivenom for the treatment for crotaline snakebite in the United States. Arch Intern Med. 2001;161(16):2030-2036. 3. Lavonas EJ, Gerardo CJ, O'Malley G, et al. Initial experience with Crotalidae polyvalent immune Fab (ovine) antivenom in the treatment of copperhead snakebite. Ann Emerg Med. 2004;43(2):200-206. 4. Khobrani M, Huckleberry Y, Boesen KJ, Aljabri A, Alharthi M, Patanwala AE. Incidence of allergic reactions to Crotalidae polyvalent immune Fab. Clin Toxicol. 2019;57(3):164-167. 5. Kleinschmidt K, Ruha AM, Campleman S, Brent J, Wax P; ToxIC North American Snakebite Registry Group. Acute adverse events associated with the administration of Crotalidae polyvalent immune Fab antivenom within the North American Snakebite Registry. Clin Toxicol. 2018;56(11):1115-1120.