A Comparison of Clopidogrel Responsiveness in Patients With Versus Without Chronic Renal Failure

We sought to compare the platelet responsiveness to clopidogrel between patients with chronic renal failure and those with normal renal function. We conducted a prospective, randomized, open-label, single-center trial. A total of 23 patients with normal renal function received a usual daily dose of 75 mg of clopidogrel (group I, 61 ± 7 years). Also, 36 patients with chronic renal failure (60 ± 5 years) were divided into 2 groups according to their daily dose of clopidogrel: a daily dose of 75 mg of clopidogrel for 30 days (group II, n = 18) or a daily dose of 150 mg (group III, n = 18). The primary efficacy variables among the study groups using the VerifyNow P2Y12 assay were the P2Y12 reaction unit value and the percentage of inhibition. A significant difference was found in the P2Y12 reaction unit value among the 3 groups (239 ± 87 in group I, 308 ± 70 in group II, 302 ± 81 in group III (p = 0.013) and in the percentage of inhibition (35 ± 20 in group I, 21 ± 16 in group II, 23 ± 14 in group III, p = 0.026). No significant difference was found in the P2Y12 reaction units or percentage of inhibition between groups II and III. In conclusion, platelet responsiveness to clopidogrel decreased more in patients with chronic renal failure than in those with normal renal function, and this decreased platelet responsiveness to clopidogrel was not improved by an increase in the clopidogrel dosage.