Dabigatran in atrial fibrillation: pharmacology and clinical trials

The central pharmacologic approach to stroke prevention in atrial fibrillation has recently changed with the approval of dabigatran by the US Food and Drug Administration (FDA). Dabigatran is an oral anticoagulant that belongs to the class of direct thrombin inhibitors. Dabigatran has predictable pharmacokinetics, without significant drug and food interactions, rapid onset, and requires twice-daily administration without the need for monitoring. The only drug contraindicated with dabigatran is rifampin. In the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial, dabigatran at a dose of 150 mg bid is statistically superior to warfarin in preventing strokes and systemic embolism in patients with atrial fibrillation and has a lower non-statistically significant rate of major bleeding. There is significantly lower rate of intracranial bleeding. The FDA recently approved the 150-mg bid dose for patients with a creatinine clearance above 30 mL/min and 75 mg bid for use in patients with a creatinine clearance of 15 to 30 mL/min. A prespecified subanalysis in both warfarin-experienced and warfarin-naive subgroups mirrored the main results. For cardioversions, a post hoc analysis showed that the rate of thromboembolism and major bleeding within 30 days of cardioversion for dabigatran 150 mg bid was low and comparable to that of warfarin, with or without transesophageal echocardiography guidance. Dabigatran, therefore, is the first novel anticoagulant to offer an alternative to warfarin.