title: The active metabolite of prasugrel effectively blocks the platelet P2Y12 receptor and inhibits procoagulant and pro-inflammatory platelet responses.
abstract: The aim of these studies was to investigate the extent of platelet P2Y(12) receptor inhibition by the thienopyridine active metabolite of prasugrel, R-138727. Blood was taken from healthy volunteers and pre-incubated with R-138727 or cangrelor (AR-C66931MX). Platelet aggregation was assessed in platelet rich plasma (PRP) and whole blood (WB). Vasodilator stimulated phosphoprotein (VASP) phosphorylation, platelet procoagulant activity (annexin V binding and microparticle formation) and calcium mobilisation were measured by flow cytometry. Platelet-leukocyte co-aggregate formation and sCD40L release, both pro-inflammatory responses of platelets, were measured by flow cytometry and ELISA, respectively. P2Y(12) receptor antagonism was determined using a radioligand binding assay ((33)P 2-MeSADP) in resting and stimulated platelets and the effects of clopidogrel administration were also assessed. R-138727 yielded concentration-dependent inhibition of platelet aggregation, VASP phosphorylation inhibition, procoagulant activity and pro-inflammatory responses. In the presence of R-138727 or cangrelor there was increased calcium reuptake following agonist stimulation. R-138727 30 micromol/L and cangrelor 1 micromol/L completely inhibited (33)P 2-MeSADP binding, compared to partial inhibition following clopidogrel administration. Platelet activation and granule secretion did not expose an additional pool of P2Y(12) receptors. Prasugrel's active metabolite effectively blocks the P2Y(12) receptor with the highest concentrations tested yielding complete inhibition of P2Y(12)-mediated amplification of several important platelet responses.
authors.affiliation: University of Sheffield, Sheffield, UK. H.Judge@Sheffield.ac.uk
authors.forename: Heather M
authors.initials: HM
authors.lastname: Judge
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Buckland
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Sugidachi
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Jakubowski
authors.forename: Robert F
authors.initials: RF
authors.lastname: Storey
mesh_terms: D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000328:Adult; D017304:Annexin A5 / Q000378:metabolism; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D000077144:Clopidogrel; D003594:Cytoplasmic Granules / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008840:Microfilament Proteins / Q000378:metabolism; D008875:Middle Aged; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010879:Piperazines / Q000378:metabolism / Q000494:pharmacology*; D015539:Platelet Activation; D010974:Platelet Aggregation; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D000068799:Prasugrel Hydrochloride; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058925:Receptors, Purinergic P2Y12; D013876:Thiophenes / Q000378:metabolism / Q000494:pharmacology*; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000494:pharmacology; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D017304:Annexin A5; D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; C548576:P2RY12 protein, human; D010750:Phosphoproteins; D010879:Piperazines; D010975:Platelet Aggregation Inhibitors; D058919:Purinergic P2 Receptor Antagonists; C510685:R-138727; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D013876:Thiophenes; D000098662:Vasodilator-Stimulated Phosphoprotein; D000249:Adenosine Monophosphate; C117446:cangrelor; D000077144:Clopidogrel; D000068799:Prasugrel Hydrochloride; D013988:Ticlopidine