Protective Effect of Oral Xemilofiban in Arterial Thrombosis in Dogs Increased Activity in Combination With Aspirin

Background—Inhibition of platelet aggregation by preventing the binding of fibrinogen to glycoprotein (GP) IIb/IIIa on activated platelets results in antithrombotic activity. We report on the antithrombotic effect of xemilofiban (SC-54684A), an oral GP IIb/IIIa antagonist, administered alone or with aspirin (ASA) in an acute thrombosis model. Methods and Results—Conscious dogs were treated with xemilofiban (1.25, 2.5, 5.0, or 6 mg/kg, n=6); low-dose (LD, 81 mg) ASA, n=7; high-dose (HD, 162 mg) ASA, n=6; xemilofibran 1.25 mg/kg plus LD ASA, n=6; xemilofibran 1.25 mg/kg plus HD ASA, n=6; or placebo, n=7. Dogs were anesthetized 60 minutes later, and the effects of the treatments were evaluated after electrolytic injury (250 μA for 180 minutes) in the left circumflex coronary artery. Bleeding time (BT) was assessed in a separate study. Incidence of thrombosis was reduced (P<0.05) by xemilofiban ≥2.5 mg/kg, HD ASA, or xemilofiban 1.25 mg/kg plus HD ASA compared with placebo. Xemilofiban ≥2.5 mg/kg or xemilofib...