Studies of 2 new oral anticoagulants, rivaroxaban and dabigatran, in joint replacement patients have yielded positive results for prevention of venous thromboembolism (VTE). Results of the studies were recently presented at the 2007 Congress of the International Society on Thrombosis and Hemostasis. Results obtained with rivaroxaban suggested superior efficacy and similar bleeding rates when compared with enoxaparin. Two studies were presented for dabigatran, the results of which were conflicting. In the RE-NOVATE trial, dabigatran showed equivalence to 40 mg of enoxaparin, while in the RE-MOBILIZE study it failed to show equivalence to a 60-mg dose of enoxaparin.
The 2 new oral anticoagulants are among a number of compounds under development that may one day replace warfarin. Neither of the drugs needs regular monitoring. Liver-toxicity problems, which caused a predecessor drug (ximelagatran) to be rejected by the FDA, have not been noted. Dabigatran appears closest to market, having already been filed for approval in Europe. Approval applications for prevention of VTE are expected to be filed for rivaroxaban in the United States in 2008. Both drugs are also under study for use in atrial fibrillation and acute coronary syndromes.