What can ongoing clinical trials of anticoagulants demonstrate?

As the population ages, the burden of thromboembolic disease increases. The development of new anticoagulants that overcome the shortcomings of the vitamin K antagonists represents an important advance.Clinical evaluation of new anticoagulants typically begins in short-term indications, such as prophylaxis against venous thromboembolism in patients undergoing orthopaedic surgery, followed by investigation in chronic conditions, such as stroke prevention in patients with atrial fibrillation. Factors for consideration in clinical trials include methodological issues (blinded versus open-label; active-control statistical designs; patient selection, etc.). Despite its subsequent withdrawal, clinical trials of ximelagatran demonstrated the efficacy of fixed doses of an oral, direct thrombin inhibitor for prevention of thromboembolism. Direct and indirect inhibition of activated Factor X is another target for new anticoagulants. Evidence-based data from trials such as these will pave the way for new anticoagulants, with the goal of bringing optimum prophylactic therapy to those requiring anticoagulation.