CROFAB[R] FOR TREATMENT OF RATTLESNAKE ENVENOMATION

Background: CroFab antivenin was recently FDA-approved. Methods: Prospectively collected data from 7 CroFab-treated rattlesnake bites seen in March/April 2001. Our treatment guideline, based on package insert, comprised attempts at initial control followed by 2 vials every 6 hrs x 3 doses with repeat outpatient labs 48-72 hrs later. Control was defined as a halt in proximal swelling and normal fibrinogen (fib), PT, and platelet count. Results: 7 pts received 1st doses of 6 or 8 vials in attempts to achieve control, but additional initial vials were given if control was not achieved. 2 pts with fib levels [is less than] 35 mg/dL remained hypofibrinogenemic despite 22 and 28 initial vials CroFab. Fib levels then became normal with scheduled dosing of 2 vials q 6 hrs, but both had recurrence of afibrinogenemia within 72 hrs. Both were readmitted and retreated, but neither achieved normal fib despite 12 and 19 additional vials of CroFab. 2 pts had thrombocytopenia which corrected with 6 vials without recurrence. 7 pts had swelling, and we achieved initial control of swelling in all pts with 6 to 16 vials. 2 pts then redeveloped progressive swelling during the next 24 hrs despite receiving 2 vials q 6 hrs. No immediate hypersensitivity reactions or serum sickness has been seen to date. Antivenin expenses and length of hospitalization were much greater than those with past use of Wyeth Antivenin. Conclusion: Initial 'control' of coagulopathy is frequently difficult to achieve with CroFab, and recurrence of severe coagulopathy developed within a few days of discontinuing CroFab. Swelling can progress after what appears to be initial control, despite regular dosing of antivenin.
Ruha AM, Beuhler M, Brooks D, Wallace K, Graeme KA, Curry SC, Gerkin R, Lovecchio F. Good Samaritan Regional Medical Center, Phoenix [...]