Dosing and Administration

Dose and Administer CroFab® Appropriately to Gain and Continue Control of Envenomation1,2

  • Administer CroFab® as soon as possible in patients who develop any signs of envenomation (e.g., local injury, coagulation abnormality, or systemic signs of envenomation) to prevent clinical deterioration. CroFab® was shown in clinical studies to be effective when given within 6 hours of snakebite
  • CroFab® is available as a lyophilized powder

Administering CroFab® to Achieve Control1:

  • 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

Dosing to Gain Initial Control1:

  • The starting dose of CroFab® may vary from a minimum of 4 vials to a maximum of 12 vials based on clinical judgement and severity of envenomation
  • If necessary, administer an additional 6 vials of CroFab® ~1 hour after end of first infusion

Vial imagery



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


Dosing to Continue Control1:

Continue CroFab® dosing to help prevent recurrent venom effects1

  • Treat adult and pediatric patients with scheduled maintenance dosing after initial control is established
  • Administer an additional 2-vial dose of CroFab® every 6 hours for up to 18 hours (a total of 3 doses)

Maintenance therapy is additional CroFab® given after initial control to prevent recurrence of venom effects.


2-vial dose every 6 hours



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


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.4

  • Significant hypofibrinogenemia and thrombocytopenia lasting up to 2 weeks may occur after envenomation by North American pit vipers1
  • 53% of patients with initial control of moderate pit viper envenomation had recurrent, persistent, or late coagulopathy 2 to 14 days later4
  • 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


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).

 

*P=0.04.
Not statistcally significant vs. placebo.
Follow-up data not available for 1 patient.

Reconstituting CroFab®


Reconstituting CroFab®

Administering CroFab®

  • Establish IV access and give IV fluids
  • Pediatric CroFab® dose = adult dose
  • Mix 4-6 vials of CroFab® in 250 mL normal saline (0.9% sodium chloride) and infuse IV over 1 hour
    • Initial dose may vary from a minimum of 4 to a maximum of 12 vials based on clinical judgment and severity of envenomation
    • Infuse the dose intravenously over 60 minutes. However, the infusion should proceed slowly over the first 10 minutes at a 25-50 mL/hour rate with careful observation for any allergic reaction. If no such reaction occurs, the infusion rate may be increased to the full 250 mL/hour rate until completion. Close patient monitoring is necessary
      • Post-marketing data reports low rates of acute (8%) and delayed (13%) hypersensitivity5
  • For patients in shock or with serious active bleeding, call physician-expert
  • Initiate first dose of CroFab® in ED or ICU
  • 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

Learn about purity, precision, and purpose with CroFab®.

References:

1. CroFab® [prescribing Information]. BTG International Inc; May 2017. 2. 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. 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. 4. Boyer LV, Seifert SA, Clark RF, et al. Recurrent and persistent coagulopathy following pit viper envenomation. Arch Intern Med. 1999;159(7):706-710. 5. Schaeffer TH, Khatri V, Reifler LM, Lavonas EJ. Incidence of immediate hypersensitivity reaction and serum sickness following administration of crotalidae polyvalent immune Fab antivenom: A meta-analysis. Acad Emerg Med. 2012;19:121- 131.