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Drug-drug interactions

CYP inhibition and CYP induction assays

CYP inhibition and CYP induction assays are vital in early drug research to evaluate a drug’s impact on cytochrome P450 (CYP) enzymes involved in metabolism. CYP inhibition assays determine if a compound interferes with CYP enzymes, potentially altering drug exposure and leading to drug–drug interactions, resulting in toxicity or reduced efficacy. Induction assays assess whether a compound increases CYP enzyme expression, potentially accelerating metabolism and decreasing the efficacy of other drugs. These assays help identify potential interactions, enhancing safety and efficacy and supporting your drug discovery efforts by minimising the risk of adverse interactions.

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Expert CYP inhibition and induction assays for drug–drug interaction evaluation

The inhibition of CYP enzymes can significantly impact the metabolism of co-administered drugs, potentially leading to increased plasma levels and associated adverse events. The severity of these drug–drug interactions depends on the potency and mechanism of inhibition (reversible or irreversible). Our CYP inhibition laboratory uses state-of-the-art equipment to offer a high-throughput screening assay for all major CYP enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4/5). In our human liver microsome (hLM) assay, we incubate CYP-isoform-specific substrates in the presence of different test compound concentrations. The metabolite formation is determined using LC-MS/MS bioanalysis and compared to a solvent control. The concentration of test compound that results in 50% inhibition (IC50) of the isoform-specific transformation is reported. Depending on your needs, the assay can be performed with or without a pre-incubation period to investigate the time dependency of the inhibition.  

 
We also offer assays for time-dependent inhibitory effects to investigate mechanism-based inhibition (MBI) on CYP3A4. Our high-throughput screening MBI involves incubating various concentrations of test compounds in hLM with and without a fixed pre-incubation period to derive a screening-level inhibitory constant (Ki) and kinact. A similar manual assay is available that uses multiple pre-incubation periods to evaluate a comprehensive Ki and kinact.  
 

CYP induction can be mediated through mechanisms such as activation of nuclear receptors, including the pregnane X receptor (PXR), aryl hydrocarbon receptor (AhR) or constitutive androstane receptor (CAR). Our CYP induction assay is optimised to detect induction of CYP1A2, CYP2B6 and CYP3A4 on mRNA expression and enzyme activity levels, serving as surrogates for PXR, AhR and CAR activation. HepaRG cells are incubated with different concentrations of test compounds, and gene expression changes are determined by qRT-PCR. Parallel LC-MS/MS analysis of metabolite formation from CYP-isoform-specific reactions measures changes in activity. Additionally, our assay provides information on cell viability using microscopy and biochemical cytotoxicity measurements.  
 

Our CYP inhibition and induction assays will help you identify and mitigate DDI-related safety liabilities during your lead optimisation phase by screening individual compounds or entire NCE libraries. Contact our experienced scientists for specific questions and support on assay choice, evaluation and interpretation of results.

 
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