FDA approves first antivenom for Centruroides scorpion stings

FDA has approved the first antivenom treatment specifically for stings from Centruroides scorpions in the United States. The new biologic treatment called Anascorp was designated an orphan drug and given priority review because adequate treatment did not exist in the United States, according to a consumer update and corresponding news release issued by the agency.

Anascorp is indicated for the treatment of clinical signs of scorpion envenomation.

“Scorpion stings can be life-threatening, especially in infants and children,” said

Karen Midthun, MD, director of FDA’s Center for Biologics Evaluation and Research in the news release.

FDA’s decision on Anascorp’s effectiveness was based on the results of a randomized, double-blind, placebo-controlled trial of 15 children with neurological signs of scorpion stings. The symptoms which can include can include fluid in the lungs, breathing problems, excess saliva, blurred vision, slurred speech, trouble swallowing, abnormal eye movements, and muscle twitching resolved within 4 hours of treatment in the 8 subjects who received Anascorp. Only one of the 7 participants who received the placebo had resolution of symptoms as quickly. In total, safety and efficacy data was collected from 1,534 patients in both open-label and blinded studies, which were led by the University of Arizona.

Anascorp, Centruroides (Scorpion) Immune F(ab')2 (Equine) Injection, is made from the plasma of  horses immunized with scorpion venom. Although the manufacturing process for Anascorp includes steps to decrease the chance of allergic reactions and to reduce the risk of transmission of viruses that may be present in the plasma, the drug may cause early or delayed allergic reactions in people sensitive to horse proteins, the statement said.

The most common side effects of Anascorp were vomiting, fever, rash, nausea, itchiness, headache, runny nose, and muscle pain.

Anascorp is licensed to Rare Disease Therapeutics, Franklin, Tenn., distributed by Accredo Health Group, Memphis, Tenn., and manufactured by Instituto Bioclon, S.A. de C.V., of Tlalpan, Mexico, D.F.

According to FDA statements, Jude McNally, the medical science liaison at Rare Disease Therapeutics, said the Tennessee company will market the new drug to any healthcare facility that accepts emergency patients in areas were the bark scorpion is found, including Arizona, and areas of Clark County, Nev., and parts of New Mexico where the bark scorpion has established colonies, he said.