Snake venom takes bite out of strokes
By Lindsay Butler, Tribune
September 21, 2006
In the past, Barbara Corkins wouldn’t go near a snake. But after a treatment made from pit viper venom saved her life during a stroke, she’s warmed up slightly to the slithery creatures.
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“I’m glad to see them now,” she said.
The 69-year-old Scottsdale resident was one of the first participants in a Mayo Clinic study testing Viprinex to treat ischemic stroke, or a stroke caused by a blood clot in the brain.
The drug is made from the venom of a Malayan pit viper, and so far has shown to be effective in breaking up clots and thinning the blood to prevent clots from growing.
The Mayo Clinic hospital in northeast Phoenix is the only site in Arizona to participate in the year-old study. During the next few years, the 50 hospitals in the study aim to enroll 500 patients, and eventually apply for Food and Drug Administration approval.
The American Stroke Association reports an American suffers from stroke every 45 seconds, with 157,000 people dying annually.
It ranks third as a cause of death after heart disease and cancer, and is the No. 1 cause of disability.
Until now, patients have received tissue plasminogen activator, or TPA, at the onset of the stroke. But the drug had limitations: It had to be given within three hours of the stroke, 6 percent of patients would hemorrhage after treatment and 3 percent would die.
If stroke patients arrived at the hospital outside the threehour window, there was nothing doctors could do but focus on rehabilitation, said Dr. Bart Demaerschalk, principal invest- igator at the Mayo Clinic.
“There was nothing reversing the stroke as it was happening — no acute treatment,” he said. “The brain was irreversibly injured.”
Viprinex, on the other hand, has a six-hour window of treatment and a lower risk of hemorrhage, he said.
Demaerschalk said stroke patients admitted within three hours will still receive TPA, but those who come in later will be offered the experimental drug.
In Corkins’ case, the treatment sounded like the only chance for recovery, said her husband, Sid.
The Corkinses were enjoying a quiet Sunday afternoon at home in May when Barbara Corkins began feeling faint and slurring her speech. Within a couple hours, she was paralyzed on her right side.
She was admitted to the Mayo Clinic just before 6 p.m. By the time she had a CT scan and lab work, the three-hour window had passed, and Demaerschalk offered the experimental drug. Sid Corkins signed the consent form.
“The clock was ticking, and it was important to make a decision quickly,” he said.
By her second day in the hospital, Barbara Corkins began improving. In the three months that followed, she left the hospital and underwent physical therapy to begin walking again. She now shows only a slight limp. The brain can only withstand a blockage for so long before it suffers damage, Demaerschalk said.
“Disability is one of the things people, if you ask them, really fear the most, even more than death,” he said. “A stroke can rob them of all the qualities that make them feel humanistic.
“To be able to save one person from such an outcome is a huge impact. There’s not a day goes by I don’t see tragedy. That’s what we’re trying to prevent.”
The Mayo Clinic has enrolled four stroke patients in the study so far; the other patients are doing well, Demaerschalk said.
Collecting venom
Snakes are positioned with their mouth open and fangs extended through a membrane on the top of a container. Venom is highly modified saliva made of hundreds or thousands of proteins and enzymes, many of which are toxic.
Unclogging an artery
Scientists use extracts from the venom to create Viprinex, a drug that promotes blood flow, breaks open clots and has less risk of hemorrhage than the traditional treatment.
Warning signs of stroke
Numbness or weakness in the face, arm or leg, especially on one side of the body Confusion, affected speaking or understanding Trouble seeing in one or both eyes Difficulty walking, dizziness, loss of balance or coordination Severe headache with no known cause
SOURCE: American Stroke Association
Contact Lindsay Butler by telephone at (480) 898-6500.
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KEYWORD:
VIPRINEX |
