Effect of naftazone on in vivo platelet function in the rat

The aim of this study was to investigate the in vivo effects of 50 mg/kg (i .p.) naftazone or ticlopidine on platelet functions in the rat. An automate d isotope monitoring system (Aims plus) nas used to determine the height of platelet aggregation and disaggregation (measured hi. the area under the c urve, AUC) of (111)indium-labelled platelets activated by ADP (10 mu g/kg i .v.) or collagen (50 mu g/kg i.v.). Fibrinogen-binding experiments were car ried out with activated platelets in whole blood and measured by flow cytom etry. Naftazone reduced the height of platelet aggregation induced by ADP c ompared with controls (P = 0.003). Ticlopidine-treated rats gave similar re sults (P = 0.008). Platelet disaggregation, following the aggregation induc ed by collagen, was significantly increased in naftazone-treated rats compa red with controls (P = 0.003). Similar results were observed with ticlopidi ne-treated rats (P = 0.002). Fibrinogen binding to 2.5 or 5 mu M ADP-stimul ated platelets, from naftazone-treated rats, were significantly reduced com pared with controls (P = 0.05 and 0.01 respectively). These results show th at naftazone has similar inhibitory effects on rat platelet functions as ti cloplidine. In conclusion, naftazone could be a useful agent to modulate pl atelet function in patients with cardiovascular disease.