Greater inhibition of platelet aggregation and reduced response variability with prasugrel versus clopidogrel: An integrated analysis

Multiple studies report response variability to a 300-mg clopidogrel loading dose (LD). Pooled platelet aggregometry data compared responses (change in maximal platelet aggregation [Delta MPA] or inhibition of platelet aggregation [IPA]) to clopidogrel 300-mg (n = 131) or prasugrel 60-mg (n = 109) LDs. Poor responder rates were determined using empiric criteria (IPA < 10% and Delta AMPA < 10% for 20 mu M and 5 mu M adenosine diphosphate [ADP]) and Bayesian model-based criteria (IPA < 20% and Delta AMPA < 15% for 20 mu M ADP; IPA < 25% and Delta AMPA < 20% for 5 mu M ADP). Prasugrel achieved greater Delta AMPA and IPA from 2 to 24 hours post-LD (P < .00 1). For 20 mu M ADP, poor responder rates for clopidogrel ranged from 17% to 43%; no prasugrel poor responders were observed. Regardless of the criterion, prasugrel 60 mg achieved greater IPA and fewer poor responders than the clopidogrel 300-mg LD.