7-(Ethoxycarbonyl)-6,8-dimethyl-2-phenyl-1(2H)-phthalazinone derivatives: synthesis and inhibitory effects on platelet aggregation.

7-(Ethoxycarbonyl)-6,8-dimethyl-2-phenyl-1(2H)-phthalazinone derivatives and several analogues were synthesized and their inhibitory effects on platelet aggregation were evaluated. Structure-activity relationships are discussed. All synthesized compounds showed no appreciable effect on platelet aggregation induced by adenosine diphosphate, but most of them inhibited effectively the arachidonic acid induced platelet aggregation. The parent compound, 2-phenyl derivatives, and ortho-substituted 2-phenyl derivatives show the most potent inhibition of all compounds.