New anticoagulants for the treatment of venous thromboembolism.

In recent years, the significant limitations associated with the use of vitamin K antagonists (VKA) have encouraged the development of new agents. Based upon the central roles played by the serine proteases thrombin and Factor Xa in the blood coagulation cascade, direct thrombin inhibitors and direct Factor Xa inhibitors have been developed. These agents, which include the direct thrombin inhibitor dabigatran etexilate and the Factor Xa inhibitors rivaroxaban and idrabiotaparinux are free from many of the limitations of VKAs. According to the results of available phase III randomized clinical trials, both dabigatran and rivaroxaban are effective and safe enough to qualify as ideal oral anticoagulants for the initial and long-term treatment of patients with acute venous thromboembolism (VTE). Rivaroxaban does not require an initial parenteral treatment and can be given in once daily administrations after the first three weeks. Both of them have limitations for the treatment of patients with severe renal failure, and require further investigations in cancer patients and in pregnant patients with VTE. Both of them lack an antidote.