Three subjects were administered clopidogrel orally at three dose levels: 75 mg, 150 mg, and 300 mg. Two separate aliquots of blood were drawn from the subjects at the following time points: pre-dose, 0.25, 0.50, 1, 2, and 4 hours post dose. The first aliquot of blood was drawn into an EDTA tube for analysis of parent clopidogrel. The second aliquot of blood was drawn into an EDTA tube pretreated with 30 µL of 500 mM of MPB to immediately derivatize the clopidogrel active metabolite for accurate analyses.