by Michael W. Harkness
On August 4, FDA approved the biological product Anascorp® (Centruroides (Scorpion) Immune F(ab')2 (Equine) Injection. Anascorp® is the first U.S. government-approved treatment for bark scorpion venom. Bark scorpions, also called Arizona bark scorpions, are the most venomous scorpion in North America, and are common in southeastern California, southwestern Arizona and other parts of the Sonoran Desert in Mexico. About 11,000 people a year are stung by bark scorpions in Arizona alone. Bark scorpion stings can cause severe pain, convulsions, loss of breath, and in rare cases, even death. The Mexican-produced Anascorp® had been available in Mexico before receiving orphan drug status and an expedited review process by FDA. Anascorp®, developed by Mexican company Instituto Bioclon, is created from the plasma of horses that are immunized with bark scorpion venom. In the U.S., the biological license application ("BLA") is held by Rare Disease Therapeutics, Inc., located in Franklin, Texas.
Bark scorpions are an especially dangerous threat to small children. The University of Arizona, working with Instituto Bioclon to get Anascorp® approved, responded by focusing their drug studies on the effectiveness of the drug in children. The University's research team released one of their studies in 2009 that found that most of the 15 children who received Anascorp® after a bark scorpion attack recovered within two hours. Children stung by bark scorpions who did not have access to the drug had to be sedated in order to stop the progression of the drug in the body, and in some cases had to be put on breathing machines in order to overcome the intense pain, loss of muscle control, and breathing problems associated with the stings. The venom acts as a nerve poison, and triggers nerves that cause convulsions and muscle spasms.
According to the University of Arizona pediatrician who led the clinical trials of Anascorp®, Dr. Leslie Boyer, the approval of Anascorp marks the first time that FDA has approved a drug that was made and developed in Latin America. Dr. Boyer is head of the Venom Immunochemistry, Pharmacology and Emergency Response Institute at the University of Arizona, the institute that lead the clinical trials for Anascorp®. The clinical trials were conducted on over 2,000 people at 26 hospitals in Arizona and one in Las Vegas. The reported side effects of Anascorp® from the trial included vomiting, fever, rash, nausea, itchiness, and headache.