Drug evaluation: rivaroxaban, an oral, direct inhibitor of activated factor X.

Bayer AG and Ortho-McNeil Pharmaceutical Inc are developing rivaroxaban, an oral Factor Xa inhibitor, for the potential prevention and treatment of thrombosis. In December 2005 and December 2006, phase III trials were initiated for the prevention of venous thromboembolism (VTE) following major orthopedic surgery and in patients with atrial fibrillation, respectively. By January 2007, a phase III trial for the prevention of VTE following total knee replacement surgery had commenced. In November 2006, a phase II trial for the reduction of VTE in patients with acute coronary syndrome was initiated.