Prasugrel.This novel thirdgeneration rapid-acting thienopyridine is a more potent blocker of the platelet P2Y12 receptor than is clopidogrel,57,63 and no resistance has been reported.57 The 60-mg loading dose achieves faster, more consistent, and greater inhibition of adenosine diphosphate–induced platelet aggregation than does 600 mg clopidogrel. Prasugrel produces a significantly greater effect than clopidogrel as early as 30 minutes after administration.64 Prasugrel is superior to clopidogrel in preventing ischemic events in patients with acute coronary syndrome undergoing PCI, even though there is an associated greater risk of bleeding.24,35,57,65 Prasugrel therapy should be individualized and targeted toward those patients with stents or patients with decreased platelet inhibition by clopidogrel.57 Patients with a history of cerebrovascular events have experienced significant harm from administration of prasugrel.35 Prasugrel has a black box warning, not to be used in patients with previous stroke or transient ischemic attack because of its greater tendency to cause intensive inhibition of platelet aggregation in general and the findings of increasedlevels of bleeding compared with clopidogrel