The results of a small study suggest that desmoteplase, an investigational clot-busting drug derived from vampire bat saliva, safely restores blood supply to the brain when administered up to 9 hours after a stroke occurs.

Dr. Anthony Furlan of the Cleveland Clinic Foundation in Ohio said that the rate of blood flow restoration in stroke patients who were randomly assigned to intravenous treatment with desmoteplase was 53.3 percent, compared with 37.5 percent in patients randomly assigned to receive placebo.

Furlan presented results of the Dose Escalation study of Desmoteplase in Acute Ischemic Stroke (DEDAS) at a late-breaking clinical trials session on Friday at the American Stroke Association International Stroke Conference 2005.

A lower dose of desmoteplase was not superior to placebo. However this dose was effective in an earlier European study and Furlan said it will be investigated in a large, multinational study of desmoteplase that will begin enrollment in April.

In terms of safety, there were no symptomatic episodes of bleeding in the brain, a potential side effect of this type of therapy. An earlier study of desmoteplase reported one symptomatic bleeding episode.

“Combining both studies the hemorrhage rate was 2 percent, which is less than the 6 percent hemorrhage rate reported with tissue plasminogen activator,” he said. Tissue plasminogen activator, or tPA, is another clot-dissolving drug, which is currently on the market.

Furlan presented the results for 37 patients who were treated within 3 to 9 hours after they had a stroke. All of the patients had a National Institutes of Health Stroke Score (NIHSS) between 4 and 20.

Eight patients were randomly assigned to receive placebo, 14 to low-dose desmoteplase and 15 to a higher dose of desmoteplase.

After 90 days, 9 patients in the high-dose arm had clinical improvement (60 percent) versus 2 in the placebo arm (25 percent) and 4 in the lower dose arm (28.6 percent)

The study was funded by Paion Pharmaceutical in Aachen, Germany. The phase III trial will be supported by Forest Pharmaceuticals of St. Louis.