Further studies on the effects of epimers of thromboxane A2 antagonists on platelets and veins.

The C-15 hydroxy epimers of three TXA2/PGH2 antagonists were resolved by HPLC and their pharmacology evaluated in canine saphenous veins and human platelets. For all three compounds, the epimers were equipotent in their ability to antagonize U46619 (1 microM) induced platelet aggregation. In contrast, one of the epimers for all three of the antagonists was significantly more potent than the other in antagonizing U46619 (10 nM) induced saphenous vein contractions. The data support the notion that the TXA2/PGH2 receptors in veins may be different from those in platelets.