The oral activity and antithrombotic efficacy of BMY 42393 was examined in ex vivo platelet aggregation studies and arterial thrombosis animal models. In a heterologous ex vivo platelet aggregation assay, ADP-induced human platelet aggregation was inhibited when washed human platelets were combined with rat platelet-poor plasma, taken from rats previously orally-dosed with BMY 42393. The IC50 for platelet aggregation inhibition was approximately 10 mg/kg. In a laser-induced thrombosis model, thrombus formation in a revascularized rabbit ear chamber was prevented in a dose-dependent fashion with an ED50 of about 2 mg/kg. A relatively long duration of anti-thrombotic activity was observed in the rabbit ear laser-induced thrombus study and the ex vivo platelet studies. Inhibition of thrombus formation was also demonstrated in a canine model of electrically-induced coronary artery thrombosis. BMY 42393 also prevented cyclic flow reductions in a monkey stenotic renal artery model. These studies indicate that BMY 42393 is orally active and capable of preventing laser and electric current-induced thrombus formation in animal models of arterial thrombosis.