CYP inhibition screening, direct and time-dependent
In the CYP assay, the test compound is preincubated with human liver microsomes at selected concentrations in the presence and absence of cofactor NADPH. Thereafter, CYP activity is measured by incubating the human liver microsomes with a cocktail of CYP-specific substrates (1A2, 2B6, 2C8, 2C9, 2D6, 2C19 and 3A) in the presence of NADPH. Direct inhibition is observed from the samples pre-incubated in the absence of NADPH as reduced level of CYP-specific metabolite formation in the incubations compared to solvent samples. Time-dependent (TDI) inhibition is detected as changes in inhibition curves after preincubation in the absence and presence of NADPH. One concentration of specific positive control inhibitors for CYP3A are used; for direct and TDI inhibition, respectively (to determine % inhibition and % TDI).
Test concentrations: 2
Time points: 1
Replicates: 2
Positive control
UPLC/MS/MS analysis
Background
Inhibition of cytochrome P450 (CYP) enzymes by a new chemical entity (NCE) may decrease the metabolism of co-medicated drugs. We offer assays for individual enzymes as well as a cocktail approach to determine inhibition towards multiple enzymes in the same incubation. Liver microsomes are recommended for high-throughput screenings and for mechanistic approach. In addition, CYP inhibition evaluation can be conducted using pooled hepatocytes, for compounds where hepatocytes are a better suited model.
