Inhibitory effects of various kinds of antiplatelet agents on platelet adhesion to subendothelium

Numerous studies have supported that platelets have an important role for thrombus formation. Therefore, some kinds of antiplatelet agents have been widely used as antithrombotic agents. We investigated inhibitory effects of these agents on platelet adhesion to subendothelium using the method of Baumgartner. Aspirin (50-100mg/kg) or flurbiprofen (2-3mg/kg) was given to children with mucocutaneous lymphnode syndrome and dipyridamole (400-500mg/day), trapidil (300-400mg/day) or ticlopidine (300-400mg/day) was given to normal adults. After administration of these drugs for 3 days, 10ml of citrated blood was taken from each person to observe platelet adhesion. Platelet adhesion was expressed as a percentage of that in normal subjects. The most effective drug was aspirin (31.9±7.9%), and all other agents also inhibited platelet adhesion indicating the following values: dipyridamole (43.9±18.7%), flurbiprofen (61.5±29.9%), ticlopidine (64.5±11.1%) and trapidil (66.5±29.9%). We estimated the ratio of number of thrombi to that of adhesion (T/A). The ratio observed in normal adults was 0.41±0.27 and the lowest was 0.05±0.04 of trapidil. The results suggest that all of these agents had inhibitory effects on platelet adhesion and thrombus formation.