Crotalid snakebites can range from mild to life-threatening, depending on the size and type of snake, the amount of venom injected and the location of the bite. This in turn determines the number of vials of CroFab that are required by the patient. Untreated, the snake venom can cause severe pain and tissue damage that can result in the loss of a limb or even death. Prompt treatment with CroFab is recommended. 'Fab' refers to Fragment Antigen-Binding, the active mechanism for this antivenom.
Adverse events
The most common adverse events reported in clinical studies were mild or moderate reactions involving the skin and appendages, which occurred in 14 out of 42 patients. Three patients experienced a serious adverse event. Two patients had a severe allergic reaction following treatment. One patient had a recurrent coagulopathy due to envenomation, which required re-hospitalisation and additional antivenin administration. In clinical trials, recurrent coagulopathy, characterised by decreased fibrinogen, decreased platelets and elevated prothrombin time, occurred in approximately half of the patients studied. Recurrent coagulopathy may persist for one to two weeks or more. One patient discontinued CroFab therapy due to an allergic reaction. Patients with allergies to papain, chymopapain, other papaya extracts or the pineapple enzymebromelain may also be at risk for an allergic reaction to CroFab.
Cost
Leslie Boyer, Director of the VIPER Institute, who was on the team that developed CroFab, said they were "crestfallen" to discover that the wholesale price of Anascorp, their latest antivenom, was too high to be cost effective, even in the treatment of critically ill children. The industry website Fierce Pharma called the product a “drug launch disaster” and “one of the most bizarre marketing tales in the industry.” Boyer said that CroFab, a US drug whose sister product retailed in Mexico at $100, was resulting in bills to Arizona patients of between $7,900 and $39,652 per vial. One person rejected treatment and died because he couldn't afford to pay for it. Boyer collected data on the cost of production and marketing, and found that the largest true cost to payers, $4100/vial, was that of the legal, regulatory and hospital activities involved in selling the drug. Clinical trials contributed $300/vial, and 25% of that had been paid for by government grants. Other costs were the same as in Mexico.
