New anticoagulants and their potential impact on the treatment of thromboembolic disease.

Traditional anticoagulants have drawbacks that make them complex to manage, limit their usefulness, and increase the possibility of adverse events. New anticoagulants are being developed that directly target a single coagulation factor. The agents have improved pharmacokinetics and pharmacodynamics and may not need coagulation monitoring. In addition, many are available orally. Agents that target factor Xa or factor IIa are the most advanced in development and of greatest interest. Fondaparinux and idraparinux are parenteral, specific, indirect, factor Xa inhibitors that have a mechanism of action similar to that of heparin. Idraparinux has a prolonged half-life and is dosed once weekly. Razaxaban is a small-molecule, oral, direct FXa inhibitor with demonstrated efficacy in orthopedic surgery for primary prevention of venous thromboembolism. Other oral Xa inhibitors are entering clinical trials. Ximelagatran is an oral factor IIa or thrombin inhibitor with documented efficacy for primary prevention of venous thromboembolism in orthopedic surgery, for the acute and chronic treatment of deep venous thrombosis and stroke prevention in atrial fibrillation. Other oral IIa inhibitors are entering clinical trials. Many of these agents will have a profound effect on the treatment of venous thromboembolism potentially resulting in reduced costs, improved patient satisfaction with treatment, and greater use of selected indications.