Table 1.

IC₅₀ (µM) values for inhibition of clopidogrel biotransformation by human liver microsomes (HLM) and for the antiplatelet effect of clopidogrel in the presence of CYP3A4 inhibitors or substrates

	IC50 for biotransformation by HLM (µM)	IC50 for antiplatelet effect (µM)
Ketoconazole	0.03 ± 0.07	0.55 ± 0.06
Clarithromycin	0.33 ± 0.09	0.95 ± 0.04
Simvastatin	1.28 ± 0.09	1.29 ± 0.02
Atorvastatin	16.9 ± 0.3	3.83 ± 0.07

The assay conditions are described in Methods. The clopidogrel concentration was 40 µM for all incubations. Data are expressed as mean ± SEM of n = 4–8 experiments.