What is the recommended dosing regimen for Crofab (crotaline immune fab) for the treatment of snake bites?

CroFab Dosing for Snake Bite

The recommended initial dose of CroFab (crotaline immune fab) for snake bite treatment is 4 to 6 vials administered intravenously, with the potential to use up to 12 vials based on clinical judgment and severity of envenomation. 1

Initial Dosing Protocol

• Administer CroFab as soon as possible in patients who develop any signs of envenomation to prevent clinical deterioration 1
• The recommended initial dose is 4 to 6 vials, though this may vary from a minimum of 4 vials to a maximum of 12 vials based on clinical judgment and severity of envenomation 1
• Observe the patient for up to 1 hour following completion of the first dose to determine if initial control of envenomation has been achieved 1
• Initial control is achieved when local signs of envenomation are arrested (leading edge of local injury is not progressing), systemic symptoms are resolved, and coagulation parameters have normalized or are trending toward normal 1
• If initial control is not achieved by the first dose, an additional dose of 4 to 6 vials should be administered repeatedly until initial control of the envenomation syndrome has been achieved 1

Maintenance Dosing

• Once initial control has been achieved, additional 2-vial doses of CroFab every 6 hours for up to 18 hours (3 doses) are recommended 1
• Optimal dosing following the 18-hour scheduled dose of CroFab has not been determined 1
• Additional 2-vial doses may be administered as deemed necessary by the treating physician, based on the patient's clinical course 1

Administration Method

• Reconstitute each vial with 18 mL of 0.9% Sodium Chloride and mix by continuous manual inversion until no solid material is visible 1
• Further dilute the contents of all reconstituted vials to a total volume of 250 mL with 0.9% Sodium Chloride 1
• Infuse the dose intravenously over 60 minutes 1
• The infusion should proceed slowly over the first 10 minutes at a 25-50 mL/hour rate with careful observation for any allergic reaction 1
• If no allergic reaction occurs, the infusion rate may be increased to the full 250 mL/hour rate until completion 1

Preparation Tips for Faster Reconstitution

• Research suggests that filling vials completely with 25 mL of sterile water for injection and hand mixing results in significantly shorter dissolution times (median 1.1 minutes) compared to the manufacturer's recommended 10 mL (which can take over 25 minutes) 2
• Hand mixing is more effective than mechanical agitation or leaving vials undisturbed 2

Special Considerations

• The median dose of CroFab used to obtain initial control in severe envenomation cases has been reported as 6 vials (range: 4-18 vials) 3
• For patients with persistent, recurrent, or late-onset hematologic abnormalities, continuous intravenous infusion of CroFab at 2-4 vials per day for 6-14 days post-envenomation has been reported to be effective 4
• Infusion reactions such as fever, low back pain, wheezing, and nausea may be related to the rate of infusion and can be controlled by decreasing the rate of administration 1

Monitoring and Follow-up

• Close patient monitoring is necessary during administration 1
• Monitor for recurrent and/or delayed-onset severe defibrination syndrome, which has been reported particularly in patients who did not receive recommended maintenance CroFab dosing 3
• Poison control centers are a helpful resource for individual treatment advice 1

Pitfalls to Avoid

• Failure to administer maintenance doses may lead to recurrence of venom effects 3
• Delaying transport to a medical facility to attempt ineffective first aid measures 5
• Applying ice, using suction devices, applying electric shock, or using tourniquets, as these are ineffective and potentially harmful 5