Anticoagulants (Thrombin Inhibitors) and Aspirin Synergize With P2Y ₁₂ Receptor Antagonism in Thrombosis

Abstract

Background-This study was designed to determine whether (1) P2Y 12 antagonism synergizes with other antithrombotics and (2) anticoagulants (thrombin inhibitors) affect the antithrombotic activity elicited by P2Y 12 antagonism. Methods and Results-Thrombosis was achieved by perfusion of human and murine blood through type III collagencoated capillaries at arterial shear rate. CT50547, a direct-acting P2Y 12 antagonist, inhibited thrombosis in PPACK-but not heparin-anticoagulated human blood. In contrast, CT50547 inhibited thrombosis in aspirin-treated individuals independently of the anticoagulant. Thrombin and TXA 2 also synergized with P2Y 12 in the absence of anticoagulation, because combined treatment of aspirin or C921-78 (a factor Xa inhibitor) with CT50547 or 2-MeSAMP (a P2Y 12 antagonist) inhibited the thrombotic process, whereas all treatments failed to inhibit thrombosis when used individually. Synergism was also observed ex vivo when P2Y 12 -deficient (P2Y 12 Ϫ/Ϫ ) mice were administered aspirin or coagulation inhibitors (C921-78 and bivalirudin). Finally, using intravital microscopy, we found that both C921-78 and bivalirudin abrogated the thrombotic process in P2Y 12 ϩ/Ϫ mice, whereas each showed only partial efficacy in P2Y 12 ϩ/ϩ animals. Conclusions-Our study indicates that (1)

Therapeutic approaches in arterial thrombosis

“…However, when more than one of these targets was inhibited, pronounced antithrombotic activity was observed. In another experiment, when human blood was anticoagulated with an FXa inhibitor and perfused through a chamber in the real-time assay, we observed that P2Y 12 antagonism with clopidogrel did not affect the for 4 min and quantified as described [23]. mice demonstrate a cyclic thrombotic process in vivo, but only a qualitative difference (i.e.…”

“…A potent synergism between clopidogrel and anticoagulants [using either a direct thrombin inhibitor (Bivalirudin), a FXa inhibitor or a synthetic LMW heparin] has also been observed ( Fig. 2) [23,24]. While these results may have a simple explanation, resulting from the inhibition of fibrin formation by the anticoagulant, where fibrin contributes to thrombus stability under arterial shear rate [25], the emerging data indicate that the anti-thrombotic synergisms may originate from the complementation of the signaling pathways in platelets.…”

“…However, rather than an additive effect, the two drugs used together were synergistic [22,23]. A potent synergism between clopidogrel and anticoagulants [using either a direct thrombin inhibitor (Bivalirudin), a FXa inhibitor or a synthetic LMW heparin] has also been observed ( Fig.…”

Platelet-derived S100 family member myeloid-related protein-14 regulates thrombosis

“…We examined the role of MRP-14 in platelet thrombus formation under physiologic arterial shear conditions using a highly automated dynamic flow system (20,21). Thrombus formation was achieved by perfusion of anticoagulated blood labeled with rhodamine 6G through collagen-coated rectangular capillaries at an arterial shear rate of 625 s -1 .…”

Thienopyridines, but Not Elinogrel, Result in Off-Target Effects at the Vessel Wall That Contribute to Bleeding

“…) was achieved and recorded as described previously with minor modifications (André et al, 2003b). Platelets were labeled in situ using rhodamine 6G (0.2 mg/ml) administered through the tail vein 10 min before visualization of the arteries.…”