Characterization of Bay U 3405, a novel thromboxane A2/endoperoxide receptor antagonist.

The thromboxane A2-receptor antagonistic properties of Bay U 3405 [(3R)-3-(4-fluorophenylsulfonamido)-1,2,3,4-tetrahydro-9-carbaz o-lepropanoic acid] have been evaluated in various pharmacologic models. Bay U 3405 specifically inhibits platelet aggregation induced by U 46619, collagen, platelet-activating factor, and the second wave of ADP (IC50 0.5, 0.07, 0.3, 0.19 microM) in human plasma. The plasma phase of ADP-induced aggregation is not affected. U 46619-induced platelet aggregation is competitively antagonized (pA2 = 6.3). In humans, ex vivo platelet aggregation is inhibited after oral application of 2 or 50 mg Bay U 3405. Bay U 3405 also specifically and competitively antagonizes U 46619-induced contractions of rabbit aortic rings (pA2 = 7.4). In vivo, Bay U 3405 protects rabbits dose dependently from arachidonic acid or collagen-induced thromboembolism (ED50 1-3 mg/kg p.o). Chronic administration of Bay U 3405 to stroke-prone spontaneously hypertensive rats reduces stroke-related mortality and diminishes the occurrence of cerebral hemorrhages. From these results, we conclude that Bay U 3405 is an orally active, selective, and competitive thromboxane A2-receptor antagonist that may be beneficial in the treatment of cardiovascular or cerebrovascular diseases.