title: Switching patients from clopidogrel to prasugrel in acute coronary syndrome: impact of the clopidogrel loading dose on platelet reactivity.
abstract: OBJECTIVE
  The present study aimed to assess the pharmacodynamic response of a prasugrel 60-mg loading dose (LD) alone compared with prasugrel 60 mg added to clopidogrel 600 mg.
  
  
  BACKGROUND
  Patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) commonly receive a clopidogrel LD prior to angiography. Switching these patients to prasugrel may be desirable because higher platelet inhibition is expected.
  
  
  METHODS
  In this open-label, multicenter, nonrandomized trial, 75 patients were categorized into 2 treatment strategies: Those who received a clopidogrel 600-mg LD and received a reloading dose of prasugrel 60 mg (clopidogrel/prasugrel group) and those who did not receive a clopidogrel LD and received a prasugrel 60-mg LD (prasugrel group). Platelet reactivity was assessed using VerifyNow P2Y12 reaction units (PRU) and Platelet Reactivity Index vasodilator-stimulated phosphoprotein phosphorylation (PRI-VASP) at 3 different times: at the sheath insertion prior to prasugrel LD, 4 hours after prasugrel LD, and at discharge.
  
  
  RESULTS
  Four hours after prasugrel LD, platelet reactivity did not differ between the clopidogrel/prasugrel group and the prasugrel group according to the VerifyNow assay (median PRU 23 [5-71] vs. 54 [5-91], respectively; P = 0.18) and the VASP assay (median PRI 8.67 [4.51-16.85] versus 8.03 [4.82-21.72], respectively; P = 1.0). No significant differences in PRU and PRI were observed at discharge. Few bleeding events were reported without any significant differences between the 2 groups.
  
  
  CONCLUSIONS
  Platelet reactivity with prasugrel 60 mg added to a clopidogrel 600-mg LD was not significantly different compared with prasugrel 60 mg alone in ACS patients undergoing PCI.
authors.affiliation: MedStar Washington Hospital Center, Washington, District of Columbia.
authors.forename: Thibault
authors.initials: T
authors.lastname: Lhermusier
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lipinski
authors.forename: David
authors.initials: D
authors.lastname: Drenning
authors.forename: Steven
authors.initials: S
authors.lastname: Marso
authors.forename: Fang
authors.initials: F
authors.lastname: Chen
authors.forename: Rebecca
authors.initials: R
authors.lastname: Torguson
authors.forename: Ron
authors.initials: R
authors.lastname: Waksman
mesh_terms: D054058:Acute Coronary Syndrome / Q000628:therapy*; D000077144:Clopidogrel; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D062645:Percutaneous Coronary Intervention; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D000068799:Prasugrel Hydrochloride / Q000008:administration & dosage*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D000068799:Prasugrel Hydrochloride; D013988:Ticlopidine