Pharmacodynamic and pharmacokinetic basics of rivaroxaban

Rivaroxaban, an oral, direct factor Xa inhibitor, is a small molecule drug capable of inhibiting not only free factor Xa with high selectivity but also prothrombinase-bound and clot-associated factor Xa in a concentration-dependent manner. Clinical studies have demonstrated predictable anticoagulation and confirmed dose-proportional effects for rivaroxaban in humans with a rapid onset (within 24 h) and a half-life of 711 h and 1113 h for young and elderly subjects, respectively. For a 10 mg dose, the oral bioavailability of rivaroxaban is high (80100%) and is not affected by food intake. These favourable pharmacological properties underpin the use of rivaroxaban in fixed dosing regimens, with no need for dose adjustment or routine coagulation monitoring. Rivaroxaban has a dual mode of excretion with the renal route accounting for one-third of the overall elimination of unchanged active drug. Rivaroxaban is a substrate of CYP3A4 and P-glycoprotein and therefore not recommended for concomitant use with strong inhibitors of both pathways, e.g. most azole antimycotics and protease inhibitors. Rivaroxaban is currently approved for the prevention of venous thromboembolism (VTE) in adult patients undergoing elective hip or knee replacement surgery. Studies using 10 mg rivaroxaban once daily in this indication demonstrated its suitability for a wide range of patients regardless of age, gender or body weight. Further studies in the treatment of VTE, prevention of cardiovascular events in patients with acute coronary syndrome, prevention of stroke in those with atrial fibrillation and prevention of VTE in hospitalized medically ill patients have been reported or are ongoing.