FDA grants approval to scorpion antivenom tested by UA team

August 12, 2011

By hammersmith

After twelve years of investigation, a scorpion antivenom tested under the direction of University of Arizona researchers has been approved by the U.S. Food and Drug Administration. The new drug, which will be sold under the name Anascorp, has proved dramatically effective in reducing the potentially life-threatening symptoms of bark-scorpion stings.

“This is an historic event,” said Leslie Boyer, director of UA’s VIPER Institute (Venom Immunochemistry, Pharmacology, and Emergency Response Institute). “This is the first-ever drug approved for this use by the FDA; the first-ever drug that we are aware of being developed fully in Latin America and subsequently approved by the FDA; the first-ever scorpion antivenom proved effective under controlled clinical trials; and the first-ever antivenom with so few allergic reactions.”

Bark-scorpion stings are virtually unknown in the United States outside of Arizona, but within the state some 8,000 stings each year lead to an average of 200 intensive-care hospitalizations for serious complications.

“We in Arizona felt very isolated; we felt abandoned,” Dr. Boyer said on National Public Radio. “This was an orphan disease.”

Anascorp was initially developed by the Mexico City-based firm Instituto Bioclon to treat victims of scorpion stings. In infants and young children, the neurotoxins in bark-scorpion venom can cause breathing difficulties, uncontrollable muscle spasms, and potentially death. Prior to the development of Anascorp, scorpion envenomation caused hundreds of deaths in Mexico each year. But as Dr. Boyer witnessed on a 1999 visit to meet with researchers in Cuernavaca, the antivenom is rapidly and powerfully effective, virtually obviating the need for complicated emergency medical intervention.

“Mexico has been in the antivenom field for many years, and over many years we have accumulated a big experience on how to make good antivenoms,” said Alejandro Alagón of the Institute of Biotechnology of the National Autonomous University of Mexico, on NPR.

Two years ago, Dr. Boyer, Dr. Alagón, and their colleagues published the results of a key study of Anascorp that was conducted in Tucson in 2004-2005. Since that small study, which involved only 15 children stung by scorpions, much broader investigation has enabled nearly 2,000 children stung by scorpions to receive the antivenom. A network of hospitals–27 in Arizona and one more in Nevada–participated in the project.

A companion study based at PHS Indian Hospital on the San Carlos Apache Indian Reservation confirmed the safety of Anascorp in a rural setting, one of the most important questions that Dr. Boyer’s team had to resolve before FDA approval. Historically, the occasional deaths that have occurred in Arizona from scorpion stings have primarily resulted from difficulty getting patients to advanced medical care quickly enough. 

Now that the FDA has approved the new drug, it should soon be carried in most Arizona hospitals. With widespread availability will come far fewer frantic races to receive care.

“The biggest problem was patients having to be transferred to other hospitals,” said Dr. Michelle Ruha, a medical toxicologist at Banner Good Samaritan’s Poison and Drug Information Center, in the Arizona Republic. “Their condition would worsen during that time.”

Dr. Boyer noted the broad coalition of researchers and funders who backed the testing of Anascorp over the past decade. The Office of Orphan Products Development of the FDA provided a grant for the 2004-2005 study in Tucson; later, more support came from the Arizona Department of Health Services and the Arizona Biomedical Research Commission. Instituto Bioclon and a U.S. pharmaceutical manufacturer, Rare Disease Therapeutics Inc., provided the antivenom to hospitals participating in the studies.

“This project owes its success to the hard work and participation of thousands of people,” Dr. Boyer said.

For more information:

Mexico To The Rescue in America’s ‘Venom Belt’,” National Public Radio, 08/06/2011

Scorpion antivenin gets FDA’s OK,” Arizona Republic, 08/04/2011

FDA Approves Antivenom Produced in Mexico,” KJZZ Fronteras Desk, 08/03/2011

FDA Approves the First Specific Treatment for Scorpion Stings,” U.S. Food and Drug Administration news release, 08/03/2011

UA Scorpion Antivenom Collaboration Gains FDA Approval,” University of Arizona video segment, 08/03/2011

UA Scorpion Antivenom Collaboration Gains FDA Approval,” University of Arizona news release, 08/03/2011