Effect of Adenosine Derivatives and Antihistaminics on Platelet Aggregation

The inhibitory activity of ade-nosine derivatives on ADP induced platelet aggregation appears to be quite specific. Only one derivative, 5′-adamantoyl adenosine, retained the potency of adenosine. Isoadenosine was 1/100 as active as adenosine. Isoadenosine diphosphate did not induce platelet aggregation at a dose as high as 2.6 × 10- M as compared to ADP which produces extensive aggregation at 4.2 × 10-7 M. All of the 6 antihistaminics tested inhibited ADP induced aggregation, but there was no correlation between antihistaminic and aggregation inhibitory potency. Both classes of compounds also inhibited collagen induced aggregation.