anticoagulant /-kō·ag″yələnt// [Gk, anti + coagulare, curdle] , 1. pertaining to a substance that prevents or delays coagulation of the blood. 2. an anticoagulant drug. Heparin is a potent anticoagulant that interferes with the formation of thromboplastin, with the conversion of prothrombin to thrombin, and with the formation of fibrin from fibrinogen. Phenindione derivatives administered orally or by injection are vitamin K antagonists that prevent coagulation by inhibiting the formation of vitamin K–dependent clotting factors. See also antithrombotic.
