| Assay Method Information | |
| | Inhibition of CYP-2C9 |
| Description: | The inhibition of cytochrome P450 2C9-isoenzyme catalyzed hydroxylation of diclofenac by the test compound is assayed at 37° C. with human liver microsomes. All assays are carried out on a robotic system in 96 well plates. The final incubation volume contains TRIS buffer (0.1 M), MgCl2 (5 mM), human liver microsomes (0.1 mg/mL), diclofenac (10 μM) and the test compound at five different concentrations or no compound (high control) in duplicate (e.g., highest concentration 10-50 μM with subsequent serial 1:4 dilutions). Following a short preincubation period, reactions are started with the cofactor (NADPH, 1 mM) and stopped by cooling the incubation down to 8° C. and subsequently by addition of one volume of acetonitrile. An internal standard solution the stable isotope 13C6-hydroxydiclofenac is added after quenching of incubations. Peak area analyte (=metabolite formed) and internal standard is determined by LC-MS/MS. The resulting peak area ratio analyte to internal standard in these incubations is compared to a control activity containing no test compound. Within each of the assay runs, the IC50 of a positive control inhibitor (sulfaphenazole) is determined. Experimental IC50 values are calculated by least square regression according to the following equation: % control activity=(100% control activity/(1+(I/IC 50)S))−B with I=inhibitor concentration; S=slope factor; B=background activity (lower plateau of the inhibition curve). |
| Affinity data for this assay | |
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