Correlation Between the CYP2C19 Phenotype Status and the Results of Three Different Platelet Function Tests in Cardiovascular Disease Patients Receiving Antiplatelet Therapy: An Emphasis on Newly Introduced Platelet Function Analyzer-200 P2Y Test

BACKGROUND: An association has been reported between CYP2C19 polymorphism and the altered antiplatelet activity of clopidogrel. We investigated this association using the newly introduced platelet function analyzer (PFA)-200 (INNOVANCE PFA-200 System; Siemens Healthcare, Germany) P2Y test. METHODS: Polymorphisms of CYP2C19*2, *3, *17 and the degree of inhibition of platelet function were determined in 83 patients. Three different platelet function tests were used to evaluate the degree of platelet inhibition and to check the association with genotype. RESULTS: The post-procedure PFA-200 values of extensive metabolizers (EM) patients (285.3+/-38.8) were higher than those of intermediate metabolizers (IM) and poor metabolizers (PM) patients (227.7+/-98.3 and 133.7+/-99.2, respectively; P=0.024). Light transmittance aggregometry (LTA) and the VerifyNow system showed that the post-procedure values for EM patients were lower than those of IM and PM patients (LTA: 24.4+/-15.7, 34.1+/-17.6, and 42.2+/-16.9, respectively, P<0.001; VerifyNow: 133.2+/-60.5, 171.5+/-42.6, and 218.7+/-59.3, respectively, P<0.001). The high residual platelet reactivity (HPR) rates were significantly different among the EM, IM, and PM groups using PFA-200 (PM:IM:EM=82.4:40.6:11.8, P<0.001). CONCLUSIONS: Approximately, 59.0% of Korean patients with cardiovascular disease receiving clopidogrel had CYP2C19 loss-of-function genotypes classified as IM or PM, and the frequency was similar to the data from Asian people. The PFA-200, LTA, and VerifyNow platelet function tests revealed evidence of a significant association between the efficacy of clopidogrel and CYP2C19 genotypes.

Lower Loading Dose of Prasugrel Compared with Conventional Loading Doses of Clopidogrel and Prasugrel in Korean Patients Undergoing Elective Coronary Angiography: A Randomized Controlled Study Evaluating Pharmacodynamic Efficacy

BACKGROUND AND OBJECTIVES: Although prasugrel allows for rapid and potent platelet inhibition, the efficacy and safety of lower doses of prasugrel for patients of East Asian ethnicity has not yet been investigated. We compared the effect of a lower loading dose (LD) of prasugrel with conventional LDs of clopidogrel and prasugrel in Korean patients. SUBJECTS AND METHODS: Forty-three Korean patients undergoing coronary angiography were enrolled in the study. Participants were randomly administered LDs of clopidogrel 600 mg, prasugrel 30 mg or prasugrel 60 mg prior to coronary angiography. Platelet reactivity was assessed at baseline and at the time of peak platelet inhibition using light transmission aggregometry (LTA), the VerifyNow assay, and multiple electrode aggregometry. RESULTS: Although baseline platelet reactivity between the groups showed no significant differences, at the time of peak platelet inhibition, the prasugrel 30 mg (18.9+/-10.0%) and 60 mg groups (13.8+/-10.8%) showed significantly more potent platelet inhibition than the clopidogrel 600 mg group (52.9+/-15.8%; p<0.001) by LTA. However, there were no significant differences between the prasugrel 30 mg and 60 mg groups (p=0.549). CONCLUSION: The loading effect of prasugrel 30 mg was more potent than clopidogrel 600 mg and was not significantly different from prasugrel 60 mg.