Antithrombotic therapy in atrial fibrillation: ximelagatran, an oral direct thrombin inhibitor.

The oral direct thrombin inhibitor ximelagatran (Exanta, AstraZeneca) is rapidly absorbed, is efficiently bioconverted to the active form, melagatran (AstraZeneca) and has shown efficacy and relative safety as an anticoagulant for prophylaxis and therapy of thromboembolism. Two Phase III trials, Stroke Prevention using an ORal Thrombin Inhibitor in atrial Fibrillation (SPORTIF V), have tested the hypothesis that oral ximelagatran, administered 36 mg twice daily without coagulation monitoring or dose adjustment, prevents stroke and systemic embolism at least as effectively as adjusted-dose warfarin (international normalized ratio, 2.0-3.0) in patients with nonvalvular atrial fibrillation. Both were randomized, multicenter trials (n > 3000 per trial) with blinded end-point assessment. The open-label SPORTIF III trial confirmed the noninferiority of ximelagatran versus warfarin. Publication of the full results from SPORTIF V is pending.