In a unanimous 9-0 vote on Sept. 20, the FDA Cardiovascular and Renal Drug Therapy Advisory Committee recommended the approval of dabigatran, an anticoagulant used to prevent stroke in atrial fibrillation patients. Yet, dabigatran's superiority over warfarin (the current anticoagulant used in atrial fibrillation patients) wasn't established, according to FDA briefing documents.
The advisory committee based its recommendation on the results of the RE-LY (Randomized Evaluation of Long-Term Anticoagulant Therapy Warfarin Compared to Dabigatran) trial, funded by Boehringer Ingelheim, the manufacturer of dabigatran, according to an FDA briefing document.
In the study, researchers randomized 18,113 atrial fibrillation patients to one of three treatments: 110 mg or 150 mg of dabigatran twice daily, or warfarin. (Read the Nov. 9, 2009 Neurology Today story, “Dabigatran Found More Effective Than Warfarin for Preventing Strokes in Atrial Fibrillation Patients” here online: http://bit.ly/bS2crd)
Researchers found the stroke rate to be the lowest in patients randomized to 150 mg of dabigatran (1.11 percent per year) compared to 1.53 percent in the 110 mg dabigatran group and 1.69 percent for patients taking warfarin.
Major bleeding was highest in the warfarin group (3.36 percent per year) and lowest in those randomized to 110 mg of dabigatran (2.71 percent).
“Physicians who are treating high-risk patients with atrial fibrillation have been seeking an alternative to warfarin,” said Harold Adams Jr., MD, professor and director of the Division of Cerebrovascular Disorders at the University of Iowa Stroke Center. “While warfarin is an excellent medication to prevent embolic stroke among persons with atrial fibrillation, it does have its limitations.”
Warfarin is known to have numerous interactions with medications and food. It also requires individual dose adjustments to achieve an INR (international normalized range) of 2 to 3 and strict monitoring of the INR level. Dabigatran, however, doesn't require either, said Dr. Adams.
Atrial fibrillation accounts for a third of all strokes in the elderly and a large portion of “bad” strokes that require therapeutic intervention, said James C. Grotta, MD, chairman of the Department of Neurology at the University of Texas Medical School at Houston, and director of the stroke program at Memorial Hermann-Texas Medical Center.
He said the main reasons why atrial fibrillation causes stroke are that “patients are either non-compliant with their [warfarin], stop taking it for a procedure, or just have substantial variability in their metabolism of the drug that leads to inadequate anticoagulation effect.” He added that dabigatran should reduce the number of such strokes and consequent disability.
Both experts who spoke to Neurology Today commended the advisory committee's decision, but they said a cost-benefit analysis is needed.
“Physicians and patients will need to consider the costs of warfarin and the monitoring versus the cost of dabigatran,” said Dr. Adams.
Ezekowitz MD, Connolly S, Parekh PA, et al. Rationale and design of RE-LY: randomized evaluation of long-term anticoagulant therapy, warfarin, compared with dabigatran. Am Heart J 2009;157:805-810.