In the September issue of the Journal of Toxicology (pp. 210), researchers from Loma Linda University suggested that patients sustaining bites from this Southern Pacific rattlesnake can be treated with up to 26 vials of the new monoclonal known as Crofab. They recommended that Crofab be re-dosed at four hour intervals if needed due to the short half-life of this compound. They also recommend that Crofab can be used up to four or five days after the evenomation.
Report A 46-year-old white male, forest ranger in excellent physical health, who at the end of his shift, changed into his running shoes and ran down the mountain in his sneakers, and thus was bitten in the back of his left lower leg by a Southern Pacific Rattlesnake. Southern Pacific Rattlesnake is known to be in the endemic area, and then known no other rattlesnakes known to be in that area. The patient then walked three miles to his car and from the Ranger Station, was helicoptered to the emergency department. On arrival, the patient had mildly swollen left leg. Initial platelets were 46,000. At that time, four vials of Crofab were administered and the patient was admitted to the hospital. Approximately four hours later, the patient had markedly increased swelling of his left lost leg requiring two repeated doses of four vials each of Crofab. The swelling continued and within 18 hours, the patient developed ecchymosis about both his legs and his flank. At this time, an additional four vials of antivenom was given was a total of 20 vials. Consult was obtained from vascular surgery, orthopedic surgery, internal medicine and hematology. The patient's pulse remained strong and was felt that no fasciotomy was needed. The patient's platelet count continued to drop and by the fifth day of hospitalization was down to 11,000. Consultations with numerous toxicologist across the country felt that further administration of Crofab at this time would not be indicated. A decision was made by hematology to transfuse with patients with platelets. The patients did not develop any neurologic dysfunction. After prolonged hospitalization, the patient was discharged with mild residual in his left leg. Current review of the packing insert on Crofab fails to show the use of Southern Pacific rattlesnake and the production of this antivenom.Recommendation at this time: The patient is sustaining severe rattle snake bites from Southern Pacific Coast rattler, not showing a robust response to the new monoclonal antibody Crofab should be administered one Crofab in the higher recommended dose of up to 26 vials or more. Practically, the patient should be given the old Wyatt's horse serum antivenom.