New oral anticoagulants: One Step Closer to Replacing Warfarin

Anticoagulants are widely used for the prevention and treatment of venous and arterial thrombosis. The main indications for long-term anticoagulation therapy include treatment of venous thromboembolism (VTE), stroke prevention in atrial fibrillation (AF) and the prevention of valve thrombosis in patients with mechanical heart valves. For the past 65 years, vitamin K antagonists (VKA), such as warfarin, have been the only available oral anticoagulants. In North America, it is estimated that at least 2.5 million people receive warfarin each year for prevention of thromboembolism on the background of atrial fibrillation or mechanical heart valves [1]. Although effective, warfarin has multiple limitations that result in its underuse in eligible patients with atrial fibrillation. These limitations have prompted the development of new oral anticoagulants that target factor Xa or thrombin. Concentrating on these new drugs, this paper (a) outlines the limitations of warfarin, (b) describes how the new oral anticoagulants overcome these limitations, (c) reviews the pharmacology of the factor Xa and thrombin inhibitors, (d) describes the results of the clinical trials with the new oral anticoagulants, and (e) provides perspective on how these drugs will streamline long-term anticoagulant therapy.