The pharmacogenetics and pharmacodynamics of clopidogrel response: an analysis from the PRINC (Plavix Response in Coronary Intervention) trial by Gladding Patrick, Webster Mark, Zeng Irene, Farrell Helen, Stewart Jim, Ruygrok Peter, Ormiston John, El-Jack Seif, Armstrong Guy, Kay Patrick, Scott Douglas, Gunes Arzu, Dahl Marja-Liisa in JACC. Cardiovascular interventions (2008). PubMed

Abstract

OBJECTIVES: 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).

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