This sounds wonderful because it could be used up to 9 hours after the stroke. Trials continue.
http://www.webmd.com/stroke/news/20050204/drug-from-bat-saliva-may-help-treat-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.
the clinical trial:
http://www.uwhealth.org/news/clinical-trial-uses-bat-saliva-enzyme-for-stroke-treatment/14180
Clinical Trial Uses Bat Saliva Enzyme for Stroke Treatment
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MADISON - Vampires aren't usually cast in the role of saviors, but stroke experts are hoping a blood thinner that mimics a chemical in vampire saliva will help save brain cells in stroke patients.
University of Wisconsin School of Medicine and Public Health is one of several centers worldwide currently enrolling patients in a large new clinical trial of desmoteplase, a drug based on an enzyme in vampire bat saliva.
The enzyme thins the blood of the bats' victims to prevent it from clotting as the bats feed. Its name comes from the scientific name for vampire bats, Desmodus Rotundus.
Early trials of the drug were encouraging that it may be able to extend the window of medical treatment up to nine hours after the onset of a stroke. The current gold standard for stroke treatment, alteplase, has been shown to be effective only up to four and one-half hours, and carries a risk of serious bleeding in a small percentage of patients.
Desmoteplase may be safer, and when used in combination with advanced brain-imaging techniques it may be effective hours later than the conventional clot-busting medicine.
After the initial promising findings, desmoteplase showed disappointing results in the second round of trials in which the entire group of patients taking it did only as well as those who got the placebo. But Dr. Matt Jensen, a UW Health stroke neurologist, says that a more careful look at the data suggest that there may be some patients who are better suited for the drug.
"We think that there is a group of patients who may benefit," he says. "With more advanced imaging, we hope to be able to identify people who are more likely to respond to the drug."
In an ischemic stroke (the most common kind), a blood clot blocks an artery to part of the brain, and over several hours without oxygenated blood, the brain cells begin to die. But Jensen explains that some patients have better circulation to the brain that allows enough blood to get around the blockage through other arteries.
This can allow the brain cells to survive longer until the blood clot is broken up, and good blood flow is restored. Physicians at UW Hospital will use advanced imaging techniques using MRI (magnetic resonance imaging) and CT (computed tomography) to find stroke patients who are better candidates for later treatments.
Jensen says that the physicians of the UW Health Comprehensive Stroke Program take calls from around the state from doctors looking to help patients who arrive too late for the standard treatments.
"As part of this trial, we will be able to treat certain people up to nine hours after the onset of stroke symptoms,'' he said. "With ground and helicopter transfers we can get people here quickly and potentially offer them a chance for this investigational treatment."
The DIAS-III trial, Desmoteplase In Acute Ischemic Stroke, plans to enroll 302 patients between December 2008 and December 2010.
Jensen stressed that it can be difficult for patients to recognize that they are having a stroke, and many people miss the chance for treatment by delaying getting medical evaluation in the nearest emergency department. The UW Health stroke site, www.uwhealth.org/stroke, has educational material including the following stroke warning signs, which should prompt an immediate 9-1-1 call:
Sudden weakness or numbness of the face, arm or leg, especially on one side of the body
Sudden confusion, trouble speaking or understanding
Sudden trouble seeing in one or both eyes
Sudden trouble walking, dizziness, loss of balance or coordination
Sudden severe and unusual headache
Date Published: 08/21/2009
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