Drug From Bat Saliva May Help Treat Stroke
Clot-Busting Drug Can Be Given Up to 9 Hours After Stroke
Feb. 4, 2005 (New Orleans) -- An experimental clot-busting drug made from the saliva of a vampire bat can restore blood flow to the brain as long as nine hours after the onset of stroke symptoms, according to new research.
The drug, called desmoteplase, was given to patients three to nine hours after a stroke, and blood flow to the brain was successfully restored in more than half of the patients who received the highest dose of the drug.
Moreover, 90 days after treatment up to 60% of patients receiving the drug improved enough to be living independently and to "complete activities of daily living," says Anthony Furlan, MD, a stroke expert at The Cleveland Clinic.
The only FDA-approved clot-busting treatment for stroke is tissue plasminogen activator, or tPA, which must be administered within three hours of a stroke.
The results of the study were reported at the American Stroke Association's International Stroke Conference 2005.
Costantino Iadecola, MD, a neurologist at Weill Medical College of Cornell University in New York, tells WebMD that desmoteplase is "one of the most promising therapies" being studied. He says the biggest obstacle to treatment of stroke patients is time; most patients simply arrive at the hospital too late for tPA treatment. Iadecola was not involved in the study.
The study looked at 38 stroke patients. They received either a high dose or low dose of desmoteplase or a placebo.
Brain imaging studies showed that 53% of the patients who received a high dose of the drug had blood restored to the brain compared with 38% in the placebo group and 18.2% in the low-dose group.
Though the lower dose was not better than placebo in this study, Furlan says it did work well in an earlier European study.
One of the big concerns about clot-busting drugs is the risk of bleeding in the brain. But in this study, none of the patients showed symptoms of brain hemorrhage, Furlan says. An earlier study of desmoteplase reported one brain hemorrhage as a result of the drug.
"Combining both studies, the hemorrhage rate was 2%, which is less than the 6% hemorrhage rate reported with tPA," he says.
Furlan says he thinks the drug worked so well because of the careful selection of patients eligible for this treatment. The study used a type of brain imaging that can identify the exact extent of brain damage caused by stroke.
That area or core is surrounded by cells that are damaged but not dead. "We are looking for salvageable cells," says Furlan. Using MRI scans, he and his colleagues identified the core stroke area and the surrounding "grey area." Patients with a larger percentage of grey area were eligible for the study.
Finally, while Furlan says he is pleased with the results of the study, he says time is still crucial in stroke treatment. "Early is always better. So while these results are promising, the important point remains: Dial 911, get to a stroke center as fast as possible," he says.
Don't ignore the warning signs of a stroke, especially if you have risk factors like high blood pressure or a history of ministrokes or diabetes. They include:
- Sudden numbness or weakness of the arm, leg, or face, especially limited to one side of the face
- Sudden confusion or trouble speaking or understanding
- Sudden trouble walking or loss of balance
- Sudden, severe headache with no known cause
The study was funded by Paion Pharmaceutical in Aachen, Germany.