FLOW CYTOMETRIC ANALYSIS OF VASP PHOSPHORYLATION IN PLATELETS TREATED WITH THE ACTIVE METABOLITE OF PRASUGREL, A P2Y12 ADP RECEPTOR ANTAGONIST
Abstract number: P-S-652
Asai1 F., Ogawa1 T., Yokouchi1 Y., Niitshu1 Y., Jakubowski2 J.A., Sugidachi1 A.
11Pharmacology and Molecular Biology Research Laboratories, Sankyo, Co., Ltd., Tokyo, Japan 22Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, United States
How-to-cite Asai F, Ogawa T, Yokouchi Y, Niitshu Y, Jakubowski JA, Sugidachi A. FLOW CYTOMETRIC ANALYSIS OF VASP PHOSPHORYLATION IN PLATELETS TREATED WITH THE ACTIVE METABOLITE OF PRASUGREL, A P2Y12 ADP RECEPTOR ANTAGONIST. J Thromb Haemost 2007; 5 Supplement 2: P-S-652
Introduction: The in vitro effects of prasugrel's active metabolite (AM) (R-138727), a P2Y12 ADP receptor antagonist, on vasodilator-stimulated phosphoprotein (VASP) phosphorylation in platelets were investigated to assess the suitability of VASP phosphorylation for evaluation of the antiplatelet effect of prasugrel.
Methods: VASP phosphorylation was measured by flow cytometry using citrated whole blood from healthy volunteers and expressed as the platelet reactivity index (PRI), an index of VASP phosphorylation. In parallel, ADP-induced platelet aggregation was measured by optical aggregometry in platelet-rich plasma (PRP).
Results: Prasugrel AM (3-300 mM) decreased the PRI in parallel with inhibition of ADP (5, 10, and 20 mM)-induced platelet aggregation in a concentration-dependent manner. There was a strong correlation (R = 0.798-0.819, P<0.0001 for 5, 10, and 20 mM ADP) between the PRI in whole blood treated with prasugrel AM and inhibition of platelet aggregation (IPA) in PRP treated with prasugrel AM. The presence of aspirin (0.3 mM) did not influence baseline or prasugrel AM-inhibited PRI. The effect of incubation time of prasugrel AM on VASP phosphorylation was investigated. In control samples treated with saline, the PRIs were almost identical at all time points (1.5 min - 24 h at room temperature). The PRI in the prasugrel AM (0.3-3 mM)-treated samples initially decreased in a time-related manner but were then stable for up to 24 h at room temperature. These results agreed with time-dependent platelet inhibition by prasugrel AM measured by ADP-induced optical aggregation.
Conclusions: VASP phosphorylation (PRI) is a reliable index of P2Y12 blockade by prasugrel AM and thus provides an alternative method to conventional aggregometry for the evaluation of antiplatelet effects of prasugrel and its active metabolite R-138727.
To cite this abstract use the following format:
Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number
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