Pharmacology: Clopidogrel is rapidly but incompletely absorbed after oral administration; absorption appears to be at least 50%. It is prodrug and is extensively metabolized in the liver, mainly to the inactive carboxylic acid derivative. The active metabolite appears to be a thiol derivative but has not been identified in plasma. Clopidogrel and the carboxylic acid derivative are highly protein bound. Clopidogrel and its metabolites are excreted in urine and in feces. After oral administration, about 50% of a dose is recovered from the urine and about 46% from the feces.