A2 (TxA,) receptor antagonist. Unlike the related series of w-chain allylic alcohols, amide 7 and its congeners were uniformly free of direct contractile activity in vitro (bovine coronary) and in vivo (anesthetized guinea pig). Amide 7 was effective in the inhibition of (a) arachidonic acid induced platelet aggregation of human platelet-rich plasma (I,= 0.18 f 0.006 pM),(b) 11, 9-epoxymethano-PGH2 induced platelet aggregation of human platelet-rich ...