Abstract
Anticoagulant therapy is thought to be necessary to prevent thrombus formation especially in patients with a cardiovascular disease. A wide variety of antiplatelet drugs was used together with warfarin for the prevention of thrombosis, such as aspirin, dipyridamole and ticlopidine. In this study, we attempted to see whether or not the plasma prothrombin level is affected in patients under an anticoagulant therapy with warfarin alone or warfarin together with these antiplatelet drugs. Over a period from May 1997 until January 1999, 126 patients under warfarin therapy with or without antiplatelet drugs were subjected to this study including 40 patients treated with warfarin alone, 28 patients together with aspirin, 15 patients together with dipyridamole and aspirin, 29 patients together with dipyridamole, and 14 patients together with ticlopidine. The prothrombin levels in these patient groups were 49.6, 57.1, 49.1, 51.1, and 51.7 ug/ml, respectively. No significant differences in the plasma prothrombin levels were observed among these groups. Furthermore, the amounts of warfarin given to the patients were not significantly different in all these groups. Based on these findings, we conclude that the plasma prothrombin level would not be affected by these antiplatelet drugs, when they are used together with warfarin.
