Viper Venom Examined to Save Stroke Sufferers

Doctors are beginning to test snake venom as a possible treatment for stroke.

ByRobert Davis, Usa Today

Apr. 9, 2008— -- The whole episode remains a blur to Kenneth Transeau of Katy, Texas, as he was transported by an air ambulance to a stroke center in Houston. But sometime after the noisy helicopter ride and the hurried hospital brain scans, Transeau went from being a stroke victim to a test subject.

Researchers began dripping an experimental drug made from viper snake venom into the veins of the 69-year-old husband, father and grandfather.

The pet supply salesman doesn't recall anybody mentioning risks. "They may have," he says. "I just knew I wanted to take it. I knew they wouldn't be testing it if it wasn't safe."

But the safety of the drug Viprinex is anything but certain.

For the record, Transeau was told of the risks, the hospital says.

His wife Irene signed the consent form, which detailed the bleeding and deaths seen in previous studies, to enroll her husband in the worldwide trial that hopes to study 650 patients.

"We're taking this (failed experiment) and transforming it" by changing the way it is administered to patients, Freiman says.

The study, launched in November 2005, is designed to determine whether infusing select parts of Malaysian viper venom into some patients can halt a stroke and prevent more brain damage.

For years, the concept has tempted scientists, who believe the way the snake's venom kills also should help doctors put the brakes on a stroke.

When a blood clot forms in the brain, doctors try to dissolve it while getting blood to flow more freely around the blockage and in smaller blood vessels nearby so that surrounding neurons can be nourished and survive.

The viper's venom causes its prey's blood to thin, a transformation that is exactly what doctors want to happen when trying to reverse a stroke caused by a clot, only on a much smaller scale.

"The snakes cause their victims to bleed to death internally," Freiman says. "It would be nice if you could thin blood out like this for stroke victims."

Transeau's case shows the typical race against time doctors face when they encounter a patient suffering a stroke. A stroke occurs when blood flow is cut off to part of the brain, either because of a blood clot or because of bleeding in the brain, causing the brain tissue to die. More than 700,000 strokes occur in the United States each year, making it the leading cause of disability and the third leading cause of death.

"In an average stroke, 2 million neurons die per minute in the first few hours so we are racing against the clock," says Transeau's doctor, David Chiu, director of the Eddy Scurlock Stroke Center at Methodist Neurological Institute in Houston. "The earlier we treat, the better the benefit."

The best drug Chiu has is the clot-busting drug known as tPA, tissue plasminogen activator, which must be given within three hours. The study of Viprinex is trying to determine whether the snake venom can give doctors twice as much time -- six hours -- to treat stroke.

Extra time is key because people often respond too slowly to signs of a stroke, experts say.

Viprinex is a new class of drug, says Warren Wasiewski, vice president and chief medical officer for Neurobiological Technologies. It makes blood flow more freely, and it may break up clots.

By reviewing what worked and what didn't work in 2,000 patients previously given the drug, researchers suspect that too much of the drug was given. The current trial reduces the amount.

Chui, who is an investigator in the study but who has no other financial ties to the company, says Viprinex "could be a major advance in the treatment of stroke" if it works. He says the trial is a reminder that even failed clinical studies can lead to advances.

"We have learned some valuable lessons from the failed trials," he says. "We have to be smarter at selecting patients who stand to benefit from treatment."

Transeau is convinced the speedy recovery that has allowed him to return to work is due to the drug. He talks fine and regained his strength and motor skills through physical therapy.

"I think if I had the placebo and not the actual pit viper venom, I don't think I would be as far along as I am today," Transeau says. "I started speaking the next day, and my writing became more legible as each day went along."

But neither he nor Chui knows whether he got the drug because it is being used in a double-blind study against a placebo. No one knows who is receiving what.

The method is considered the gold standard in clinical trials because it is thought to produce objective results.

The study might show Transeau benefited only from the speedy help. He and his family recognized the stroke from his impaired speech during a cellphone conversation. Paramedics found him on the side of the road in about 15 minutes, he says, and they called for a helicopter to take him directly to the specialty hospital where Chiu's team has experience moving swiftly against strokes.

Chui says the most immediate way to help stroke victims is for family members and friends to be more aware of signs and symptoms and for them to act fast to get patients to specialty hospitals.

"We need to do better in the community," he says. "It's not something you can afford to delay treatment for."

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