生物活性

• 描述The binding of glycoprotein (GP) IIb/IIIa receptor to fibrinogen is a prerequisite in platelet activation and aggregation. Tirofiban is a potent GPIIb/IIIa antagonist. It inhibited the aggregation of in vitro human gel-filtered platelets induced by ADP, collagen, gamma-thrombin, and U46619 with IC₅₀ values ranging from 12 nM to 31 nM. It also displayed inhibitory activity against human PRP platelet aggregation induced by ADP, collagen, gamma-thrombin, U46619, epinephrine, and arachidonic acid with IC₅₀ values ranging from 31 nM to 66 nM. Tirofiban inhibited the platelet aggregation in human, rhesus monkey, and dog whole blood with IC₅₀ values of 81, 140, and 353 nM, respectively. The intravenous administration of tirofiban (1 mg/kg) in dogs significantly inhibited ex vivo ADP-induced platelet aggregation in platelet-rich plasma (PRP) and the prolongation of template bleeding time. Continuous infusions of tirofiban (0.1-10 µg/kg/min) inhibited ex vivo platelet aggregation in PRP induced by ADP and collagen in a dose-dependent manner. Moreover, the combined treatment with tirofiban (1µg/kg/min, i.v., 120min) and ticlopidine (20 mg/kg/day, p.o., 4 days) in dogs did not change the pharmacokinetic profile of tirofiban nor the platelet count^[3].