Abstract
Vitamin K antagonists, such as warfarin, have been the mainstay in treatment and prophylaxis of venous thromboembolism. However, warfarin has many disadvantages including a narrow therapeutic window, numerous potential drug interactions, modulation of effect by alcohol and foods containing vitamin K and genetic variation in metabolism of warfarin, all of which contribute to the unpredictability of therapy. This has provided the impetus for developing new oral anticoagulants with a rapid onset of action, wide therapeutic window, predictable and reversible action, with few drug or dietary interactions, no requirement for routine coagulation monitoring or dose adjustment and acceptable cost. No single agent incorporates all these characteristics, but new factor Xa and direct thrombin inhibitors are being introduced into clinical practice that fulfil some of these aims. Here, we briefly discuss the current practice with its limitations and pitfalls, and then review important trials that have launched new oral anticoagulants into clinical practice.