Effects on thrombin generation of the platelet glycoprotein IIb/IIIa inhibitors abciximab versus tirofiban during coronary intervention

Glycoprotein (GP) IIb/IIIa receptor blockers have been shown to reduce adverse events in randomized clinical trials. 1‐ 4 Not only will these agents reduce platelet aggregation but, as activated platelets facilitate thrombin formation, these agents should also possess effects on reducing thrombin generation.5 Experimental and in vivo studies indicate that abciximab alone or in combination with standard-dose intravenous heparin decrease thrombin generation and fibrin formation. 6‐8 Furthermore, in a thrombin generation assay triggered by tissue factor, Reverter et al 9 found that c7E 3Fab (abciximab) through both GP Ilb/IIIa blockade and a v b3 blockade (vitronectin receptor) inhibited tissue factor-induced thrombin generation. 9 On the other hand, the small molecule inhibitors of the GP IIb/IIIa receptor are specific for this receptor alone and do not interact with the vitronectin receptor. Their effects in vivo on thrombin generation in human subjects have not been well studied. In this paper, we compared these antithrombin effects of tirofiban and heparin compared with abciximab and heparin on the activated clotting time (ACT), prothrombin fragment F1.2, and GP IIb/IIIa platelet receptor occupancy using a standardized protocol.