Creative Biolabs is dedicated to providing the first-class service of early drug optimizing to our customers around the world. We have developed a comprehensive testing system for in vitro DDI prediction focused on CYP activity.

A drug-drug interaction occurs when two or more drugs are administrated simultaneously. Certain components of one drug may exert inducing or inhibiting effects on the metabolism of another drug by interfering the relevant enzymes, thus causing drug inefficacy or toxic adverse effects. Cytochrome 450 (CYP) enzymes, in particular, represent the major enzyme for metabolizing the bulk of known drugs in human. CYP family has multiple members and broad substrate specificity, which makes them prone to interference. Due to the pivotal and complicated role of CYP in drug metabolism, detailed CYP assessing profiles are strictly required by FDA and EMA to validate inhibiting or inducing properties of new chemical entities (NCE) in the early developing stage. To address this issue, Creative Biolabs provides integrated testing services to help researchers fully understand CYP-related characteristics.

CYP Inhibition Test

Drug-induced CYP inhibition mainly results from three mechanisms (as shown in Fig. 1): reversible inhibition, irreversible inhibition, and quasi-irreversible inhibition. To reveal the inhibiting effects of the lead compound, we use an incubation mixture of a test substance, heterologously expressed CYP enzyme and a selective probe substrate which can be metabolized by indicated CYP with high specificity. Later, the formation of probe substrate metabolites then acts as an indicator of CYP activity.

CYP InvestigationFigure 1. Possible mechanisms of inhibition for the cytochrome P450s. (Wienkers and Heath, 2005)

Features of our CYP inhibition test:

  • Seven major CYP isoforms (including CYP1A, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and other isoforms on request are available for testing.
  • Utilization of human liver microsomes, which contains the full complement of CYP enzymes, can better resemble the native condition compared to single recombinant enzymes.
  • Isoform-specific and industry-accepted probe substrates.
  • LC-MS/MS or fluorescent method helps to monitor metabolite formation, which is rapid, low-cost and easy to operate.
  • IC50 value is determined to evaluate the CYP inhibiting effects, and Ki constant can also be generated to validate the inhibition potency and inhibition type.

CYP Induction Test

In addition to CYP inhibition, some drug components can induce CYP expression by stabilizing mRNA or mediation of nuclear receptors. Induction of CYP may result in severe DDI side effects, such as therapeutic failure caused by decreased plasma concentration, or toxic accumulation of secondary metabolites. In order to sufficiently assess this potential, Creative Biolabs offers professional CYP induction test service:

  • Three main CYP isoforms: CYP1A2, CYP2B6, and CYP3A4.
  • Dual measurement: enzymatic activity using fluorescent or LC-MS/MS quantification and mRNA levels using real-time qPCR.
  • Test platform of fresh cultured human hepatocytes recommended by PhRMA perspective.
  • Selective positive and negative controls to minimize false results.
  • Procedures performed in accordance with FDA Guidance.

CYP-reaction Phenotyping Assay

To understand the metabolism mechanism of a certain compound is also a critical part of predicting undesirable DDI. Our CYP-reaction phenotyping assay can help you to evaluate whether a test substance is susceptible to DDI or polymorphic effect. Test compounds are incubated with recombinant CYP isoforms and NADPH (reaction initiator) at 37°C, then the clearance of compounds will be monitored using LC-MS/MS. Substrate clearance and half-life data will be determined by assessing the contribution levels of individual CYP isoforms.

With qualified facilities and specialized staff, Creative Biolabs guarantees our clients comprehensive CYP investigation data to eliminate DDI liability. For more detailed information, please feel free to contact us or directly sent us an inquiry.


  1. Wienkers LC, Heath TG. (2005) “Predicting in vivo drug interactions from in vitro drug discovery data.” Nat Rev Drug Discov. 4(10):825-33.

For lab research use only.

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