“…Drugs of the Dicumarol‐indanedione type generally are regarded as antivitamin‐K in action, their effect being mediated through the mitochondria and resulting in depression of the synthesis of a number of coagulation proteins, particularly in the liver. There is impressive evidence that multiple coagulation defects occur during long‐term therapy, including those of prothrombin, Factor VII (proconvertin, SPCA), Factor IX (plasma thromboplastic component, PTC, Christmas factor), Factor X, plasma thromboplastin antecedent, the Hageman factor, and the Stuart‐Prower factor (13, 14). The prothrombin time test may not be sensitive to depression of several important plasma procoagulants, notably Factor IX and antihemophilic globulin (Factor VIII).…”