ARIZONA DAILY STAR (Tucson) 14 April 06 2-year scorpion-antivenin trials successful; FDA scrutiny next (Carla McClain)
Tucson, Arizona: An experimental drug tested on Tucson children who suffered potentially fatal scorpion stings appears ready for federal approval, University of Arizona scientists say.
The drug — an antivenin known as Anascorp — was developed in Mexico to combat the toxic nerve damage caused by the sting of the bark scorpion, found in Arizona and northern Mexico.
Statewide testing of the new antivenin during the past two years appears to show Anascorp effectively stops the severe reaction to the bark scorpion sting, which can be fatal if untreated.
"We have very strong results — we feel very good about it. We think it's time to take this drug seriously," said Dr. Leslie Boyer, a UA pediatrician and medical director of the Arizona Poison and Drug Information Center, who is heading the international study of Anascorp.
Boyer will present the study results to the U.S. Food and Drug Administration next month in a bid for approval.
During the two-year study, hospitals throughout the state — including University Medical Center and Tucson Medical Center — joined the project, and have been able to stock and use the experimental drug. So far, they have treated 50 toxic-sting victims with it in Arizona, including 20 Tucson children, Boyer said.
About 100 people — almost all children — require emergency treatment for bark scorpion stings every year in Arizona. Two have died in the past decade, according to Poison Center records.
Although the sting of this scorpion is painful to adults, it becomes life-threatening to small children, who absorb the venom much more rapidly.
"The venom goes through the child's body in a major way, affecting nerves everywhere," Boyer said. "At some point, it begins to affect the breathing, and a child can die from that."
Signs that a child is suffering a toxic nerve reaction include intense pain, profuse sweating, drooling, jerking and twitching, strange eye movements and sometimes loss of muscle control. When that happens, parents must call 911 immediately and get the child to UMC or TMC for emergency care.
Without an effective antivenin, these sting victims require immediate emergency and pediatric intensive treatment, often including breathing support. Anascorp, however, can quickly reverse the symptoms, eliminating the need for prolonged intensive care, doctors who have used it say.
Unfortunately, the small, slender bark scorpion is the most common house visitor of all Arizona scorpions. Other common types in our desert include the much larger desert hairy scorpion and the mid-sized striped-tail scorpion, though neither poses any medical threat.
Although "scorpion season" typically runs from April through October, scorpions do survive the Southern Arizona winter, and stings are reported year-round, Boyer said.
Until the late 1940s, bark scorpion stings caused more deaths in Arizona than rattlesnake bites. Around that time, UA researchers developed the first, and until now, only scorpion antivenin, using antibodies developed in goat serum.
But after supplies of that drug ran out several years ago, no company would agree to make it, because it failed to meet modern FDA standards, and caused significant side effects.
The new antivenin is derived from horse serum, and has caused no serious side effects, according to Boyer.
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