Incubation conditions for the P450 inhibitory assay and the IC50 and Ki values obtained using yeast-expressed rhP450s
| 1A2 | 2C8 | 2C9 | 2C19 | 2D6 | 3A4 | ||
|---|---|---|---|---|---|---|---|
| Fluorogenic probes | CEC | BOMCC | BOMCC | CEC | AMMC | DBF | BOMCC |
| Wavelength (nm) | ex: 409, em: 460 | ex: 409, em: 460 | ex: 409, em: 460 | ex: 409, em: 460 | ex: 390, em: 460 | ex: 485, em: 538 | ex: 409, em: 460 |
| Concentration used (μM) | 5 | 10 | 10 | 20 | 3 | 1 | 10 |
| Incubation time (min) | 15 | 15 | 15 | 20 | 40 | 10 | 10 |
| IC50 of DBZ (μM)a | >128 | 105 ± 11 | 13 ± 1 | 28 ± 2 | 73 ± 19 | 4.4 ± 0.4 | 3.1 ± 0.1 |
| Specific inhibitors | α-Naphthoflavone | Quercetin | Sulfaphenazole | Ticlopidine | Quinidine | Ketoconazole | Verapamil |
| Apparent Ki (μM)a | 0.029 ± 0.004 | 1.33 ± 0.08 | 1.06 ± 0.20 | 0.78 ± 0.09 | 0.025 ± 0.005 | 0.015 ± 0.005 | 0.011 ± 0.002b |
| Literature Ki (μM)c | 0.01 | 1.1 | 0.3 | 1.2 | 0.027 − 0.4 | 0.0037 − 0.18 | 10, 24 |
ex, excitation; em, emission; AMMC, 3-[2-(N,N-diethyl-N-methylamino)ethyl]-7-methoxy-4-methylcoumarin.
↵a Data are the means ± S.E. calculated from three independent determinations performed in duplicate.
↵b Ki value of ketoconazole with BOMCC as the probe substrate.
↵c Data from the FDA Guidance for Drug Interaction Studies (www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation/guidances/ucm072101.pdf).