Evaluation of Cytochrome P450 Probe Substrates Commonly Used by the Pharmaceutical Industry to Study in Vitro Drug Interactions (original) (raw)
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The Utility of in Vitro Cytochrome P450 Inhibition Data in the Prediction of Drug-Drug Interactions
Journal of Pharmacology and Experimental Therapeutics, 2005
The accuracy of in vitro inhibition parameters in scaling to in vivo drug-drug interactions (DDI) was examined for over 40 drugs using seven human P450-selective marker activities in pooled human liver microsomes. These data were combined with other parameters (systemic C max , estimated hepatic inlet C max , fraction unbound, and fraction of the probe drug cleared by the inhibited enzyme) to predict increases in exposure to probe drugs, and the predictions were compared with in vivo DDI gathered from clinical studies reported in the scientific literature. For drugs that had been tested as precipitants of drug interactions for more than one P450 in vivo, the order of inhibitory potencies in vitro generally aligned with the magnitude of the in vivo interactions. With the exception of many drugs known to be mechanism-based inactivators, the use of in Article, publication date, and citation information can be found at
Drug Metabolism Letters, 2019
Background: The cocktail approach of probing drug metabolizing enzymes, in particular cytochrome P450 (CYP) enzymes, is a cornerstone in clinical pharmacology studies. The first report of the famous “Pittsburg cocktail” has led the way for the availability of numerous cocktail substrate mixtures that provide options for indexing of CYP enzymes and/or evaluating the perpetrator capacity of the drug. Objective: The key objectives were: 1) To collate, tabulate, and discuss the various cocktail substrates to determine specific CYP enzyme activity in clinical pharmacology studies with specific case studies; 2) To introspect on how the cocktail approach has withstood the test of time and evolved for enabling key decision(s); 3) To provide some futuristic views on the use of cocktail in drug discovery and development. Method: The review was compiled after consultation with databases such as PubMed (NCBI database) and Google scholar to source various published literature on cocktail approac...
Cytochrome P450 Part 3: Impact of Drug-Drug Interactions
Journal of Pharmacy Practice and Research, 2009
The role of individual hepatic cytochrome P450 (CYP) enzymes in drug metabolism and the factors that modulate CYP activity are becoming increasingly well understood. These advances have resulted in a better understanding of drug-drug and drugfood interactions and an enhanced capacity to predict drug interactions that may occur with new drugs. This final article in the series describes the issues and principles that are important in identifying and assessing drug interactions that involve CYP enzymes.
Clinical pharmacology and therapeutics, 2005
Drug-drug interactions (DDIs) represent a serious problem in clinical practice. However, with knowledge gained over the past 15 years on the human drugmetabolizing enzymes, a better understanding of the underlying mechanisms behind many of the pharmacokinetic DDIs has been obtained. Previously, studies of DDIs for new drugs were carried out empirically or were gained through random clinical observations. In the past combinations of drugs chosen for investigation of DDIs were selected on the basis of the potential for introduction of toxicity of a drug with a narrow therapeutic index (eg, digoxin, theophylline, and warfarin) or if there was frequent coprescription with another agent for a given condition. However, with an increased understanding of drug-metabolizing enzymes and their roles in the metabolism of specific drugs, it is possible to apply a more mechanistic approach to assessing DDIs. In particular, the possibility of extrapolation of results of clinical DDI studies with 1 drug known to be cleared by a particular drug-metabolizing enzyme to other drugs that are cleared by that same enzyme is attractive.
Drug Metabolism and Disposition, 2009
Cytochrome P450 (P450) induction is one of the factors that can affect the pharmacokinetics of a drug molecule upon multiple dosing, and it can result in pharmacokinetic drug-drug interactions with coadministered drugs causing potential therapeutic failures. In recent years, various in vitro assays have been developed and used routinely to assess the potential for drug-drug interactions due to P450 induction. There is a desire from the pharmaceutical industry and regulatory agencies to harmonize assay methodologies, data interpretation, and the design of clinical drug-drug interaction studies. In this article, a team of 10 scientists from nine
Cytochromes P450 and experimental models of drug metabolism
Journal of Cellular and Molecular Medicine, 2002
For the development of new drugs, evaluation of drug-drug interactions with already known compounds, as well as for better understanding of metabolism pathways of various toxicants and pollutants, we studied the drug metabolism mediated by cytochromes P450. The experimental approach is based on animal drug-metabolising systems. From the ethical as well as rational reasons, the selection of an appropriate system is crucial. Here, it is necessary to decide on the basis of expected CYP system involved. For CYP1A-mediated pathways, all the commonly used experimental models are appropriate except probably the dog. On the contrary, the dog seems to be suitable for modelling of processes depending on the CYP2D. With CYP2C, which is possibly the most large and complicated subfamily, the systems based on monkey (Maccacus rhesus) may be a good representative. The CYP3A seems to be well modelled by pig or minipig CYP3A29. Detailed studies on activities with individual isolated CYP forms are needed to understand in full all aspects of inter-species differences and variations.
Inhibition and induction of human cytochrome P450 enzymes: current status
Archives of Toxicology, 2008
Variability of drug metabolism, especially that of the most important phase I enzymes or cytochrome P450 (CYP) enzymes, is an important complicating factor in many areas of pharmacology and toxicology, in drug development, preclinical toxicity studies, clinical trials, drug therapy, environmental exposures and risk assessment. These frequently enormous consequences in mind, predictive and pre-emptying measures have been a top priority in both pharmacology and toxicology. This means the development of predictive in vitro approaches. The sound prediction is always based on the firm background of basic research on the phenomena of inhibition and induction and their underlying mechanisms; consequently the description of these aspects is the purpose of this review. We cover both inhibition and induction of CYP enzymes, always keeping in mind the basic mechanisms on which to build predictive and preventive in vitro approaches. Just because validation is an essential part of any in vitro-in vivo extrapolation scenario, we cover also necessary in vivo research and findings in order to provide a proper view to justify in vitro approaches and observations.
Multiple P450 substrates in a single run: rapid and comprehensive in vitro interaction assay
European Journal of Pharmaceutical Sciences, 2005
The dramatically increased number of new chemical entities (NCE) used in drug discovery has raised a demand for efficient and rapid drug metabolism screening techniques. The aim of this study was to develop a global in vitro metabolic interaction screening test utilising the N-in-1 approach. A cocktail consisting of 10 CYP-selective probes with known kinetic, metabolic and interaction properties in vivo was incubated in a pool of human liver microsomes, and metabolites of melatonin (CYP1A2), coumarin (CYP2A6), bupropion (CYP2B6), amodiaquine (CYP2C8), tolbutamide (CYP2C9), omeprazole (CYP2C19 and CYP3A4), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1), midazolam (CYP3A4) and testosterone (CYP3A4) were analysed simultaneously using LC/TOF-MS. Performance of the method was assessed with cDNA expressed P450s and diagnostic CYP-specific inhibitors. The results were in good accordance with literature and our previous studies. The cocktail developed is suitable for fast and reliable in vitro screening of the interaction potential and characteristics of NCEs.