Antiplatelet effects of prasugrel vs. double clopidogrel in patients on hemodialysis and with high on-treatment platelet reactivity

Abstract

Background: High on-treatment platelet reactivity (HTPR) is frequent in patients on hemodialysis (HD) receiving clopidrogel. Objectives: The primary aim of this study was to determine the antiplatelet effects of prasugrel vs. high-dose clopidogrel in patients on HD with HTPR. Patients/Methods: We performed a prospective, single-center, single-blind, investigator-initiated, randomized, crossover study to compare platelet inhibition by prasugrel 10mgday -1 with that by high-dose 150mgday -1 clopidogrel in 21 patients on chronic HD with HTPR. Platelet function was assessed with the VerifyNow assay, and genotyping was performed for CYP2C19*2 carriage. Results: The primary endpoint of platelet reactivity (PR, measured in P2Y12 reaction units [PRU]) was lower in patients receiving prasugrel (least squares [LS] estimate 156.6, 95% confidence interval [CI] 132.2-181.1) than in those receiving high-dose clopidogrel (LS 279.9, 95% CI 255.4-304.3), P<0.001). The LS mean differences between the two treatments were -113.4PRU (95% CI -152.9 to -73.8, P<0.001) and -163.8PRU (95% CI -218.1 to -109.2, P<0.001) in non-carriers and carriers of at least one CYP2C19*2 allele, respectively. HTPR rates were lower for prasugrel than clopidogrel, in all patients (19% vs. 85.7%, P<0.001) and in non-carriers (25.7% vs. 80%, P=0.003). All carriers continued to show HTPR while receiving high-dose clopidogrel, but none showed it while receiving prasugrel. Conclusions: In HD patients exhibiting HTPR following standard clopidogrel treatment, prasugrel 10mgday -1 is significantly more efficient than doubling the clopidogrel dosage in achieving adequate platelet inhibition. Neither effect seems to be influenced by carriage of the loss-of-function CYP2C19*2 allele. © 2011 International Society on Thrombosis and Haemostasis.