Edoxabanimpurity 4, an impurity of Edoxaban (DU-176), is a selective, potent, and orally active inhibitor of factor Xa (FXa), exhibiting Kis of 0.561 nM for free FXa and 2.98 nM for prothrombinase. As an anticoagulant agent, Edoxaban is utilized for stroke prevention[1][2].