Effects of fluproquazone on platelet aggregation in man.

Turbidimetric investigations on platelets from healthy volunteers have shown inhibitory effects of 4-(p-fluorophenyl)-1-isopropyl-7-methyl-2(1H)-quinazolinone (fluproquazone) and acetylsalicylic acid (ASA) on both the extent and the velocity of aggregation induced by collagen. The threshold concentration of arachidonic acid needed to induce aggregation was also raised after fluproquazone was given to the donors. Whereas the inhibitory effects of fluproquazone disappear within 24 h, the qualitatively similar effects of ASA are much longer lasting (72--96 h). There is no evidence for enhancement of the effects of fluproquazone following four days of administration (100 mg t.i.d.).