Table 1.
IC50 values and inhibition constants (Ki) for ketoconazole and xenoestrogens on CYP1A- and CYP3A activities assayed in vitro.
| Compound(s) | IC50(μM)1,a | Ki(μM)1,a | IC50(μM)2,b | Ki(μM)2,b | IC50(μM)3,b |
| Ketoconazole (KC) | 0.6 (0.0)c | 0.04 – low [S] | 0.3 (0.1)c | 0.2 | 0.4c |
| 0.2 – high [S] | |||||
| Nonylphenol (NP) | 5.2 (1.1) | 3.5 | 160 (40) | Not analysed | 35 |
| Ethynylestradiol | 20 (1.2) | 5.4 – low [S] | 40 (7.1) | 54 – low [S] | 50 |
| 10.3 – high [S] | 95 – high [S] | ||||
| KC:NP (1:5) | 1.3 (0.2):6.2 (1.0) | Not analysed | 5.3 (1.1):25.0 (5.3) | Not analysed | Not analysed |
1 Hepatic Microsomal CYP1A activity; 2 Hepatic Microsomal CYP3A activity; 3 cDNA Expressed Human CYP3A4; a Substrate [S] = 7-Ethoxyresorufin; b [S] = 7-Benzyloxy-4-[trifluoromethyl]-coumarin; c Published in [22]. Each IC50 value represents the mean from 2–4 separate assays, followed by the SD, in brackets. The Ki values are estimated from one representative Dixon plot.