[Factor Xa inhibitor (rivaroxaban and drugs under investigation)].

The first factor Xa inhibitor, rivaroxaban had been released on market, and apixaban and edoxaban are preparing for clinical use in patients with atrial fibrillation. These newer antithrombotic agents are attractive for prevention of thromboembolism in patients with atrial fibrillation because of their favorable pharmacokinetic and pharmacodynamic profiles that seems to be better than that of direct thrombin inhibitor. The reports of rivaroxaban and apixaban have been showed noninferiority or superiority in their efficacy endpoints and also in safety endpoints even on fixed dose regimen without anticoagulation monitoring. There may be still present an important issue that we have to pay attention to find appropriate doses for the patients with renal impairment, aged or low body weight.