BMY-42393 is orally active and selective platelet aggregation inhibitor. BMY-42393 is also a prostacyclin partial agonist that inhibited ADP, collagen and thrombin-induced platelet aggregation (IC50 range 0.3 - 2.0 microM). BMY-42393 stimulated platelet adenylate cyclase activity (EC50 = 25 nM). Platelets treated with BMY 42393 showed an elevation of cAMP levels and activation of cAMP-dependent protein kinase. BMY 42393 also inhibited thrombin-induced elevation of intracellular free calcium. BMY 42393 competed for radiolabeled iloprost and PGE1 binding to platelet membranes (IC50; 170 nM and 130 nM, respectively).