"We think this will result in a huge shift in anti-coagulation therapy," said Gregory Albers, MD, professor of neurology and neurological sciences and director of the Stanford Stroke Center. Albers was a member of the steering committee that designed and directed the trial. Results from the 3,407-person international phase of the study will be published in the Nov. 22 issue of The Lancet. Albers and his colleagues presented results from the 3,922-person North American study at the American Heart Association meeting Nov. 11 in Orlando.
Coumadin effectively thins the blood and prevents strokes in people with a type of erratic heartbeat called atrial fibrillation. The problem is that the drug has a very narrow effective dose range - too little and it doesn't work, too much and a person bleeds excessively. The drug also interacts with other medications and with food. Because of these complications, people on Coumadin must have their blood checked and dose adjusted regularly to make sure they are protected from stroke.
"Coumadin is very effective, but more than half of the people who should be receiving it don't take the medication because of the inconvenience," Albers said.
In contrast, ximelegatran is just as effective as Coumadin but doesn't require blood tests for dose adjustment and doesn't interact with medications or food. "It's essentially one-dose-fits-all," Albers said.
Called the Stroke Prevention Using an Oral Thrombin Inhibitor in Atrial Fibrillation, or SPORTIF, the studies comparing ximelegatran to Coumadin took place in 25 countries. They included 7,329 patients who were treated with one of the two drugs for an average of nearly two years. These were the largest trials ever conducted on people with atrial fibrillation, Albers said.
During the trials, people in the two groups had similar rates of stroke or death, though those taking ximelegatran had fewer major bleeding incidents. Albers said the most important difference was that patients on Coumadin required constant dose adjustment while those on ximelegatran took the same dose throughout the trial.
Albers said that about 6 percent of people on ximelegatran had elevated levels of liver enzymes in the period between two to six months of treatment. This side effect usually disappeared without any consequences, but he said people on ximelegatran will need to have their liver function monitored during the first few months of therapy.
Albers said he expects ximelegatran to be approved by the U.S. Food and Drug Administration within the next year. It will be sold by the pharmaceutical company AstraZeneca under the brand name Exanta. Albers served as a consultant for AstraZeneca during the trial.
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