Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0268596 (EMA)
 2,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Drug metabolism mostly occurs in the liver. Cytochrome P450 (CYP) is a drug-metabolizing enzyme that is responsible for many important drug metabolism reactions. Recently, the US FDA and EU EMA have suggested that CYP enzyme induction can be measured by both enzymatic activity and mRNA expression. However, these experiments are time-consuming and their inter-assay variability can lead to misinterpretations of the results. To resolve these problems and establish a more powerful method to measure CYP induction, we determined CYP induction by using luminescent assay. Luminescent CYP assays link CYP enzyme activity to firefly luciferase luminescence technology. In this study, we measured the induction of CYP isozymes (1A2, 2B6, 2C9, and 3A4) in cryopreserved human hepatocytes (HMC424, 478, and 493) using a luminometer. We then examined the potential induction abilities (unknown so far) of mesalazine, a drug for colitis, and mosapride citrate, which is used as an antispasmodic drug. The results showed that mesalazine promotes CYP2B6 and 3A4 activities, while mosapride citrate promotes CYP1A2, 2B6, and 3A4 activities. Luminescent CYP assays offer rapid and safe advantages over LC-MS/MS and qRT-PCR methods. Furthermore, luminescent CYP assays decrease the interference between the optical properties of the test compound and the CYP substrates. Therefore, luminescent CYP assays are less labor intensive, rapid, and can be used as robust tools for high-throughput CYP screening during early drug discovery.
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PMID:Measurement of Human Cytochrome P450 Enzyme Induction Based on Mesalazine and Mosapride Citrate Treatments Using a Luminescent Assay. 2633 90

Translational and ADME Sciences Leadership Group (TALG) Induction Working Group (IWG) presents an analysis on the time-course for cytochrome P450 induction in primary human hepatocytes. Induction of CYP1A2, CYP2B6, and CYP3A4 was evaluated by seven IWG laboratories following incubation with prototypical inducers (omeprazole, phenobarbital, rifampicin, and efavirenz) for 6 to 72 hours. The effect of incubation duration and model-fitting approaches on induction parameters (Emax and EC50) and drug-drug interaction (DDI) risk assessment was determined. Despite variability in induction response across hepatocyte donors, the following recommendations are proposed: i) 48 hours should be the primary time point for in vitro assessment of induction, based on mRNA level or activity, with no further benefit from 72 hours, ii) when using mRNA, 24 hour incubations provide reliable assessment of induction and DDI risk, iii) if validated using prototypical inducers (>10-fold induction), 12-hour incubations may provide an estimate of induction potential including characterization as negative if < 2-fold induction of mRNA and no concentration-dependence, iv) atypical dose-response ('bell-shaped') curves can be addressed by removing points outside an established confidence interval and %CV, v) when maximum fold induction is well-defined, the choice of non-linear regression model has limited impact on estimated induction parameters, vi) when the maximum-fold induction is not well-defined, conservative DDI risk assessment can be obtained using sigmoidal-3-parameter fit or constraining logistic 3/4 parameter fits to the maximum observed fold induction, vii) preliminary data suggest initial slope of the fold induction curve can be used to estimate Emax/EC50 and for induction risk assessment. Significance Statement Regulatory agencies have provided inconsistent guidance on the optimum length of time to evaluate CYP induction in human hepatocytes, with the EMA recommending 72 h and the FDA suggesting 48 to 72 h. The IWG analyzed a large dataset generated by 7 member companies and determined that induction response and drug-drug risk assessment determined after 48 h incubations was representative of 72 h incubations. Additional recommendations are provided on model-fitting techniques for induction parameter estimation and addressing atypical concentration-response curves.
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PMID:Considerations from the Innovation and Quality Induction Working Group in Response to Drug-Drug Interaction Guidance from Regulatory Agencies: Guidelines on Model Fitting and Recommendations on Time Course for In Vitro CYP Induction Studies Including Impact on Drug Interaction Risk Assessment. 3313 60