title: Assessment of P2Y(12) inhibition with the point-of-care device VerifyNow P2Y12 in patients treated with prasugrel or clopidogrel coadministered with aspirin.
abstract: BACKGROUND
  Variability in response to thienopyridines has led to the development of point-of-care devices to assess adenosine diphosphate (ADP)-induced platelet aggregation. These tests need to be evaluated in comparison to reference measurements of P2Y(12) function during different thienopyridine treatments.
  
  
  METHODS
  After a run-in on 75 mg aspirin, 110 subjects were randomized to double-blind treatment with clopidogrel 600 mg loading dose (LD)/75 mg maintenance dose (MD) or prasugrel 60 mg LD/10 mg MD. Antiplatelet effects were evaluated by VerifyNow P2Y12 (VN-P2Y12) device (Accumetrics, San Diego, CA), vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay, and light transmission aggregometry (LTA). Prasugrel's and clopidogrel's active metabolite concentration were also determined.
  
  
  RESULTS
  Dose- and time-dependent inhibition of P2Y(12) was evident with VN-P2Y12. There was strong correlation with VN-P2Y12 and VASP or LTA for all treatments through a wide range of P2Y(12) function. At high levels of P2Y(12) inhibition, platelet function measured by VN-P2Y12 was maximally inhibited and could not reflect further changes seen with VASP or LTA methods. Correlation was also observed between exposure to clopidogrel's active metabolite and VN-P2Y12 during MD and LD, whereas it was observed only with prasugrel MD.
  
  
  CONCLUSIONS
  The VN-P2Y12 correlated strongly with inhibition of P2Y(12) function, as measured with either VASP or LTA. VN-P2Y12 also correlated to exposure to the active metabolite of prasugrel and clopidogrel up to levels associated with assumed saturation of the P2Y(12) receptor.
authors.affiliation: Uppsala Clinical Research Center, Department Medical Sciences and Cardiology, Uppsala University, Sweden. christoph.varenhorst@ucr.uu.se
authors.forename: Christoph
authors.initials: C
authors.lastname: Varenhorst
authors.forename: Stefan
authors.initials: S
authors.lastname: James
authors.forename: David
authors.initials: D
authors.lastname: Erlinge
authors.forename: Oscar O
authors.initials: OO
authors.lastname: Braun
authors.forename: John T
authors.initials: JT
authors.lastname: Brandt
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Winters
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Jakubowski
authors.forename: Sylvia
authors.initials: S
authors.lastname: Olofsson
authors.forename: Lars
authors.initials: L
authors.lastname: Wallentin
authors.forename: Agneta
authors.initials: A
authors.lastname: Siegbahn
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage*; D001241:Aspirin / Q000008:administration & dosage*; D000077144:Clopidogrel; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D016903:Drug Monitoring / Q000295:instrumentation*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D009904:Optical Rotation; D010766:Phosphorylation; D010879:Piperazines / Q000627:therapeutic use*; D019095:Point-of-Care Systems; D000068799:Prasugrel Hydrochloride; D058919:Purinergic P2 Receptor Antagonists; D058925:Receptors, Purinergic P2Y12; D013876:Thiophenes / Q000627:therapeutic use*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D000925:Anticoagulants; C548576:P2RY12 protein, human; D010879:Piperazines; D058919:Purinergic P2 Receptor Antagonists; D058925:Receptors, Purinergic P2Y12; D013876:Thiophenes; D000077144:Clopidogrel; D000068799:Prasugrel Hydrochloride; D013988:Ticlopidine; D001241:Aspirin