 This study will measure the percentage of platelet aggregation inhibition with a loading dose of clopidogrel 300 mg using the VerifyNow Assay System in healthy volunteers who have drank 11 oz of grapefruit juice. It will also measure the percentage of platelet aggregation inhibition with a maintenance dose of clopidogrel 75 mgday using the VerifyNow Assay System in healthy volunteers who have drank 11 oz grapefruit juice daily. 