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More Options Needed for Stroke Victims

Posted on: Friday, 21 March 2008, 01:00 CDT

As strokes remain to be the number 3 cause of death in the U.S., many researchers continue to struggle to find alternative methods of improving the odds of recovery.

As of right now, Activase, a drug created by Genentech Inc, stands alone as the only post-stroke treatment for patients within three hours of the onset of a stroke.

Developers attempting to add recovery time have experienced a series of pitfalls along the way.

Forest Laboratories discontinued their development of the clot-buster desmoteplase after tests failed to show that the drug was more effective than placebo. Results of the trial had drastic effects on German biotechnology company Paion AG, whose shares dropped 64 percent after their announcement.

However, Paion and Lundbeck A/S continue to conduct further tests as they shoot for a treatment window of nine hours.

"There is a lot of skepticism about any stroke drug due to the recent failures ... all this has frightened the large pharma companies," said Paul Freiman, chief executive of Neurobiological Technologies Inc, which has seen its shares fall about 85 percent since last March.

Neurobiological Technologies hopes upcoming results of its experimental stroke drug Viprinex will prove that it can be used to dissolve blood clots up to six hours after a stroke, with less risk of hemorrhage than Activase. The drug is derived from the venom of Malaysian pit vipers. Hemorrhaging is the biggest risk in post-stroke medication.

“A number of drugs are trying to get out to a six-hour window. That's where the field is going," said Dr. Anthony Furlan, chairman of neurology at University Hospitals Case Medical Center in Cleveland and principal investigator for clinical trials of desmoteplase.

Acute ischemic strokes account for the majority of more than 700,000 strokes in the U.S. each year. They are also the leading cause of disability and the third leading cause of death.

Viprinex contains an enzyme that reduces levels of the blood-clotting protein fibrinogen.

"It breaks up the clot in a more gentle way ... and it stays in the blood to prevent re-clotting," Freiman said.

"We have changed the treatment paradigm ... in our estimation a two-to-three hour intravenous drip at a rather high dose will give a better effect," he said.

The recent studies utilize comparative imaging. Without the exclusion of treatment, the risk of hemorrhage is too high.

"It's very clear that you can't just treat everybody after three hours ... as time goes on fewer will benefit," Dr. Furlan added.

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