Antiaggregatory efficacy and its time-course after application of acetylsalicylic acid, prostacyclin and nafazatrom in vivo.

Antiaggregatory potency and time courses of their respective efficacy were assessed for acetylsalicylic acid, prostaglandin (PGI2) and nafazatrom, a stimulator of PGI2-release from endothelial cells, and were compared in vivo. Endothelial cell damage was induced by excitation of intravascular fluoresceinisothio-cycanate-dextran. Time from onset of the noxious stimulus to aggregate appearance (TAA) was assessed and dose-dependently delayed by antithrombotic compounds. PGI2 was two orders of magnitude more effective than nafazatrom, acetylsalicylic acid was three orders of magnitude less effective than nafazatrom. Whereas the antiaggregatory potency of PGI2 decreased after 3.1 min to 50%, the antithrombotic efficacy of both, ASA and nafazatrom, further increased after a single bolus injection.