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FDA-approved antivenom eases scorpion sting

Arizona has always been a hotbed for scorpions and, since many humans came to the desert, for being stung by scorpions. A recent antivenom is "cooling" that hotbed a bit.

On Aug. 3, 2011, Rare Disease Therapeutics, Inc., and its partner, Instituto Bioclon, received approval from the U.S. Food and Drug Administration for Anascorp, an antivenom indicated for treatment of patients with clinical signs of scorpion stings.

Anascorp is the first-ever FDA-approved scorpion antivenom. It was approved after clinical studies showed the anitdote reverses signs of scorpion envenomation and reduces time spent in hospitals. The Arizona Poison and Drug Information Center was part of the clinical collaboration that led to the approval of the drug.

“As a 24-7 toxicology center with a long-recognized expertise dealing with envenomations, we were a logical point of entry for the study,” says Keith Boesen, PharmD, managing director of the Arizona Poison and Drug Information Center. “We were already getting calls from emergency room doctors about patients with scorpion stings, and were able to consult with them about the study criteria no matter what time of day the patient came in.”

During clinical studies of Anascorp, which began in 2004, the antivenom was available in more than 20 hospitals across Arizona and was used to treat more than 1,500 patients who showed severe symptoms of a scorpion sting. These symptoms include numbness at the sting site, increased heart rate, agitation, relentlessness, abnormal eye movements, drooling and breathing problems.

“The most common adverse reactions observed during the clinical study, seen in less than five percent of the patients, were vomiting, fever, rash and itching,” says Mazda Shirazi, PhD, medical director of the Arizona Poison and Drug Information Center. “Our job is  to accurately document and report any unexpected patient events now that the product is in wider use.”

The antivenom must be administered by a physician and will typically be used in hospital emergency rooms. Specialists at the Arizona Poison and Drug Information Center provide support to clinicians who administer Anascorp and report any patient responses to the antivenom immediately to the company.

The bark scorpion is the only species of scorpion in the United States that can occasionally cause these problems after stinging humans. The bark scorpion is found primarily in Arizona, but can also be found in western New Mexico and south Nevada.

“It was a really long road getting to approval,” Boesen says. "It involved many collaborations between drug companies in Mexico and the United States, multiple researchers, and hundreds of physicians, nurses and other healthcare professionals across the state. And because most of the study patients were young children, we owe a big thanks to many families too for their participation.

“Now that the antivenom is in use, we’re pleased to be working with Rare Disease Therapeutics, Inc. in the post-approval stage. We are glad to see this antivenom used to help more people throughout the state.” Boesen says.

Other articles

FDA news release

FDA consumer article

UA news release

Originally posted: Oct 28, 2014
Last updated: Oct 28, 2014