OBJECTIVE: We sought to compare platelet inhibition produced by three antiplatelet regimens. METHODS AND RESULTS: Sixty NSTE-ACS patients undergoing coronary angiography treated with aspirin and enoxaparin were randomised to receive tirofiban 0.4 microg/kg/min over 30 min plus 0.15 microg/kg/min over 24 h (A), clopidogrel 600 mg (B), clopidogrel 300 mg plus tirofiban (C); blood samples were taken at baseline and 2, 6 and 24 h after the drug administration, and were analyzed by light transmission aggregometry and flow cytometry. Treatment with clopidogrel 600 mg significantly reduced P-selectin expression in comparison with tirofiban alone at all time points (group B vs. A: P < 0.0001). However tirofiban inhibited platelet aggregation significantly more than clopidogrel 600 mg during the first 6 h (group A vs. B: P < 0.0001), and the addition of clopidogrel 300 mg did not inhibit platelet aggregation any more than tirofiban alone throughout the 24 h (group C vs. A: P = NS). All of the changes over time within each group were highly significant (P < 0.0001). CONCLUSIONS: Tirofiban leads to greater early inhibition of platelet aggregation but less suppression of P-selectin expression than clopidogrel 600 mg. The addition of clopidogrel to tirofiban does not add any anti-aggregatory effect, but reduces P-selectin expression, thus likely adding a significant biological and clinical protective effect and providing a rationale for the combined use of the two drugs.
Comparison of the effects of pretreatment with tirofiban, clopidogrel or both on the inhibition of platelet aggregation and activation in patients with acutecoronary syndromes / SOLINAS E.; GOBBI G.; DANGAS G.; MEHRAN R.; FAHY M.; IPPOLITO L.; BOLOGNESI MG.; RUENES R.; MERLINI PA.; ARDISSINO D.; VITALE M.. - In: JOURNAL OF THROMBOSIS AND THROMBOLYSIS. - ISSN 1573-742x. - 27(1)(2009), pp. 36-43. [10.1007/s11239-007-0174-x]