Inhibition of human platelet function by parsalmide.

2-Propargyloxy-5-amino-N-butyl-benzamide (parsalmide), an antiinflammatory drug, inhibits human platelet function in vitro and ex vivo. The degree of inhibition of ADP- and collagen-induced platelet aggregation "in vitro" is dose-dependent and parsalmide shows a more marked effect than equal concentrations of acetylsalicylic acid (ASA) and indometacin. Moreover, malondialdehyde levels in human PRP after addition of thrombin were inhibited at the same degree by parsalmide, ASA and indometacin. In ex vivo experiments, the administration of 400 mg p.o. of parsalmide in arthropathic patients shows a significant inhibitory effect on ADP-induced platelet aggregation at 3 and 24 h after treatment, while a drop of malondialdehyde levels was observed only at 3 h after treatment. No significant inhibitory effect was observed in collagen-induced platelet aggregation.