Prasugrel is a member of the thienopyridine class of ADP receptor inhibitors, like ticlopidine and clopidogrel. These agents reduce the aggregation ("clumping") of platelets by irreversibly binding to P2Y12 receptors. Compared to clopidogrel, prasugrel inhibits adenosine diphosphate–induced platelet aggregation more rapidly, more consistently, and to a greater extent than do standard and higher doses of clopidogrel in healthy volunteers and in patients with coronary artery disease, including those undergoing PCI. Clopidogrel, unlike prasugrel, was issued a black box warning from the FDA on March 12, 2010, as the estimated 2-14% of the US population who have low levels of the CYP2C19 liver enzyme needed to activate clopidogrel may not get the full effect. Tests are available to predict if a patient would be susceptible to this problem or not.
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