Warfarin and heparin are the traditional mainstay anticoagulant therapies for 
treating thromboembolic disease. These drugs, with a documented history of 
utility, also have inherent difficulties in usage; in particular, the 
complicated monitoring and numerous drug-drug interactions of warfarin, and the 
need for parenteral administration of heparins. New agents have recently emerged 
that target specific elements of the clotting pathway. Rivaroxaban, which 
inhibits activated factor X (Xa), is currently in clinical trials and is the 
most advanced factor Xa inhibitor. The drug offers once-daily oral dosing, with 
no need for injections, dose titration, or frequent blood tests to monitor the 
international normalised ratio. It has a rapid onset of action and, although 
there is no specific antidote, it has a short plasma elimination half-life 
(about 5-9 hours). Evidence from recently published large-scale phase III 
clinical trials shows rivaroxaban to be superior to enoxaparin for prophylaxis 
of venous thromboembolism after major orthopaedic surgery. Studies have shown 
rivaroxaban to have a sound safety profile, with an incidence of bleeding 
similar to enoxaparin in phase III clinical trials. Few side effects and 
drug-drug interactions between rivaroxaban and common medications have been 
found thus far, although some interactions with potent cytochrome P450 3A4 
inhibitors have been observed. It is hoped that rivaroxaban may be used as a 
first-line anticoagulant for prophylaxis of venous thromboembolic disease in 
postsurgical patients.