The Inhibition of Platelet Antiaggregating Activity of Clopidogrel by Atorvastatin Detected by Erythromycin Breath Test: a Metabolic Inhibition of Hepatic Cytochrome P450-3A

The objective of this study is to determine if the action of the drug called clopidogrel,
that you will start taking, will be decreased by another drug called atorvastatin, that you
will also start taking. Clopidogrel is an oral antiplatelet agent that has been shown to
prevent strokes and heart attacks. Atorvastatin is a cholesterol lowering agent.

Twenty adults 18-75 years of age requiring cholesterol-lowering agent and antiplatelet agent
therapy will be recruited for this study during their cardiology clinic visitation. In one
group, antiplatelet agent (clopidogrel) regimen will be administered first, then followed by
cholesterol-lowering medication (atorvastatin). In the second group, atorvastatin will be
administered first, followed by clopidogrel.

A new test called the erythromycin breath test will be administered to you three times
during the study to measure how your liver will metabolize these drugs. Blood samples will
also be obtained to assess platelet function. The criteria for exclusion are patient refusal
or inability to give written consent, patients with allergic reaction to erythromycin,
patients with known bleeding problems, liver disease, significant lung disease kidney
disease and pregnancy. Patients with psychiatric impairment and documented history of
substance abuse will also be excluded from the study.