Pharmacodynamic comparisons for single loading doses of prasugrel (30 mg) and clopidogrel (600 mg) in healthy Korean volunteers.

Background: Previous studies involving a loading dose (LD) of 60 mg prasugrel have suggested that active metabolite exposure and pharmacodynamic responses may be higher in persons of Asian ethnicity than in Caucasian subjects. The aim of this study was to determine the pharmacodynamic effect of an LD of 30 mg prasugrel and 600 mg clopidogrel in healthy Korean volunteers.

Methods And Results: Twelve volunteers were randomly assigned to a prasugrel or a clopidogrel group. Following a 2-week washout period, group designations and treatments were switched (6 per group). Platelet function was serially measured via light transmission aggregometry (LTA), VerifyNow and multiple electrode platelet aggregometry (MEA) assays at baseline and 0.5, 2, 6, and 24h after LD. Inhibition of platelet aggregation (IPA) at 0.5-24 h after prasugrel was significantly higher (P<0.001) than that achieved by clopidogrel. The prasugrel peak IPA at 2 h after LD was 93.7% (±6.2%) compared to the clopidogrel peak IPA at 6h after LD at 65.8% (±17.2%). The VerifyNow and MEA assay yielded results similar to those obtained by LTA.

Conclusions: In healthy Korean subjects, a 30-mg LD of prasugrel yields a more rapid, potent and consistent inhibition of platelet function than a 600-mg LD of clopidogrel.