title: The pharmacogenetics and pharmacodynamics of clopidogrel response: an analysis from the PRINC (Plavix Response in Coronary Intervention) trial.
abstract: OBJECTIVE
  This study assessed the effect of pharmacogenetics on the antiplatelet effect of clopidogrel.
  
  
  BACKGROUND
  Variability in clopidogrel response might be influenced by polymorphisms in genes coding for drug metabolism enzymes (cytochrome P450 [CYP] family), transport proteins (P-glycoprotein) and/or target proteins for the drug (adenosine diphosphate-receptor P2Y12).
  
  
  METHODS
  Sixty patients undergoing elective percutaneous coronary intervention in the randomized PRINC (Plavix Response in Coronary Intervention) trial had platelet function measured using the VerifyNow P2Y12 analyzer after a 600-mg or split 1,200-mg loading dose and after a 75- or 150-mg daily maintenance dosage. Polymerase chain reaction-based genotyping evaluated polymorphisms in the CYP2C19, CYP2C9, CYP3A4, CYP3A5, ABCB1, P2Y12, and CES genes.
  
  
  RESULTS
  CYP2C19*1*1 carriers had greater platelet inhibition 2 h after a 600-mg dose (median: 23%, range: 0% to 66%), compared with platelet inhibition in CYP2C19*2 or *4 carriers (10%, 0% to 56%, p = 0.029) and CYP2C19*17 carriers (9%, 0% to 98%, p = 0.026). CYP2C19*2 or *4 carriers had greater platelet inhibition with the higher loading dose than with the lower dose at 4 h (37%, 8% to 87% vs. 14%, 0% to 22%, p = 0.002) and responded better with the higher maintenance dose regimen (51%, 15% to 86% vs. 14%, 0% to 67%, p = 0.042).
  
  
  CONCLUSIONS
  Carriers of the CYP2C19*2 and *4 alleles showed reduced platelet inhibition after a clopidogrel 600-mg loading dose but responded to higher loading and maintenance dose regimens. Genotyping for the relevant gene polymorphisms may help to individualize and optimize clopidogrel treatment. (Australia New Zealand Clinical Trials Registry; ACTRN12606000129583).
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand. patrickg@adhb.govt.nz
authors.forename: Patrick
authors.initials: P
authors.lastname: Gladding
authors.forename: Mark
authors.initials: M
authors.lastname: Webster
authors.forename: Irene
authors.initials: I
authors.lastname: Zeng
authors.forename: Helen
authors.initials: H
authors.lastname: Farrell
authors.forename: Jim
authors.initials: J
authors.lastname: Stewart
authors.forename: Peter
authors.initials: P
authors.lastname: Ruygrok
authors.forename: John
authors.initials: J
authors.lastname: Ormiston
authors.forename: Seif
authors.initials: S
authors.lastname: El-Jack
authors.forename: Guy
authors.initials: G
authors.lastname: Armstrong
authors.forename: Patrick
authors.initials: P
authors.lastname: Kay
authors.forename: Douglas
authors.initials: D
authors.lastname: Scott
authors.forename: Arzu
authors.initials: A
authors.lastname: Gunes
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Dahl
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects / Q000295:instrumentation; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D000077144:Clopidogrel; D003324:Coronary Artery Disease / Q000097:blood / Q000235:genetics / Q000628:therapy*; D065731:Cytochrome P-450 CYP2C19; D065729:Cytochrome P-450 CYP2C9; D051544:Cytochrome P-450 CYP3A / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004351:Drug Resistance / Q000235:genetics*; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D010641:Phenotype; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D018048:Receptors, Purinergic P2 / Q000235:genetics; D058925:Receptors, Purinergic P2Y12; D015607:Stents; D013927:Thrombosis / Q000097:blood / Q000209:etiology / Q000235:genetics / Q000517:prevention & control*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism; D013997:Time Factors
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C548576:P2RY12 protein, human; D010975:Platelet Aggregation Inhibitors; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D000077144:Clopidogrel; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; C510164:CYP3A5 protein, human; D065731:Cytochrome P-450 CYP2C19; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D013988:Ticlopidine