| Assay Method Information | |
| | Inhibition Assay |
| Description: | Inhibition of cytochromes P450 (CYPs) 2C9, 2D6 and 3A4 was assessed using human liver microsomes and CYP-selective substrate metabolism reactions. 50 μl incubations were made up containing (finally) 0.2 mg/ml pooled human liver microsomes, 5 μM substrate (diclofenac for CYP2C9 [4' hydroxylase], dextromethorphan for CYP2D6 [O-demethylase] or midazolam for CYP3A4 [1' hydroxylase]), 0.25 μl, DMSO containing test inhibitor and NADPH regenerating system. Test inhibitor concentrations of 50, 16.7, 5.6, 1.9, 0.6 and 0.2 μM were assessed in singlicate. Incubations were prewarmed to 37° C. for 10 minutes before initiation by addition of NADPH regenerating system. Incubations were quenched after 5 minutes (20 minutes for dextromethorphan) by addition of 50 μl cold acetonitrile containing 20 ng/ml 4-OH-diclofenac-13C6, 20 ng/mL dextrorphan-D3 and 20 ng/mL 1-OH-midazolam-D4. Quenched incubates were stored at -20° C. for at least 1 hour before centrifugation (20,000xg, 20 minutes). Supernatants were removed and diluted 1:1 with water prior to analysis using a RapidFire sample injector system and API4000 mass spectrometer. |
| Affinity data for this assay | |
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