Preventing Recurrent Effects

Continue CroFab® Dosing to Help Prevent Recurrent Venom Effects1

With any venomous North American pit viper bite, coagulation abnormalities may persist or recur even after initial control of envenomation.2

  • Significant hypofibrinogenemia and thrombocytopenia lasting up to 2 weeks may occur after envenomation by North American pit vipers1
  • Patients receiving a regularly scheduled maintenance dose (n=14) experienced a lower incidence of coagulation abnormalities at follow-up compared with patients who were given additional doses based on perceived need (n=16)1

In a Prospective Clinical Trial Comparing As-Needed (PRN) and Maintenance Dosing Schedules3

  • 100% of patients achieved initial control of envenomation
  • A significant decrease (improvement) in mean snakebite severity score was observed across patient groups within 12 hours
  • No patient in the scheduled group received additional CroFab®, while 8 patients (50%) in the PRN group received additional doses for the first 12 hours

Recurrence of Coagulopathies at Follow-up in Scheduled and PRN Dosing Groups

Chart demonstrating fewer abnormalities with scheduled maintenance dosing

Study Description

Results are from a prospective, open-label, multicenter trial of 31 otherwise healthy patients 10 years of age or older who had suffered from minimal or moderate North American pit viper envenomation that showed evidence of progression. The study compared 2 different dosing schedules. Patients were given an initial intravenous dose of 6 vials of CroFab® with an option to re-treat with an additional 6 vials, if needed, to achieve initial control of the envenomation syndrome. Once initial control was achieved, patients were randomized to receive additional CroFab® either every 6 hours for 18 hours (scheduled group) or as needed (PRN group).


Not statistcally significant vs placebo.
Follow-up data not available for 1 patient.



1. CroFab® [prescribing Information]. BTG International Inc; January 2018. 2. Boyer LV, Seifert SA, Clark RF, et al. Recurrent and persistent coagulopathy following pit viper envenomation. Arch Intern Med. 1999;159(7):706-710. 3. Bush SP, Ruha AM, Seifert SA, et al. Comparison of F(ab’)2 versus Fab antivenom for pit viper envenomation: a prospective, blinded, multicenter, randomized clinical trial. Clin Toxicol. 2015;53(1):37-45.