CYP

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Lack of Effect of Medium Supplementation With Pyruvate and Hormones on Cytochrome P450-mediated Activity of Rat Hepatocytes in Primary Culture

Porntip Wirachwong and Jeffrey R. Fry

The loss of cytochrome P450 (CYP)-dependent activity continues to be a problem in the use of cultured hepatocytes in xenobiotic toxicity studies. It has been reported that the inclusion of pyruvate and various hormones in the culture medium improves the maintenance of various hepatic functions, including that of CYP2C11 mRNA expression. We have studied this further, by investigating the effects of the addition of pyruvate and hormones on various CYP-dependent enzyme activities and on the CYP-dependent toxicity of precocene II in rat hepatocyte cultures. No beneficial effects of this medium supplementation could be demonstrated.
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The Use of Long-term Hepatocyte Cultures for Detecting Induction of Drug Metabolising Enzymes: The Current Status

Sandra Coecke, Vera Rogiers, Martin Bayliss, José Castell, Johannes Doehmer, Gérard Fabre, Jeffrey Fry, Armin Kern and Carl Westmoreland

In this report, metabolically competent in vitro systems have been reviewed, in the context of drug metabolising enzyme induction. Based on the experience of the scientists involved, a thorough survey of the literature on metabolically competent long-term culture models was performed. Following this, a prevalidation proposal for the use of the collagen gel sandwich hepatocyte culture system for drug metabolising enzyme induction was designed, focusing on the induction of the cytochrome P450 enzymes as the principal enzymes of interest. The ultimate goal of this prevalidation proposal is to provide industry and academia with a metabolically competent in vitro alternative for long-term studies. In an initial phase, the prevalidation study will be limited to the investigation of induction. However, proposals for other long-term applications of these systems should be forwarded to the European Centre for the Validation of Alternative Methods for consideration. The prevalidation proposal deals with several issues, including: a) species; b) practical prevalidation methodology; c) enzyme inducers; and d) advantages of working with independent expert laboratories. Since it is preferable to include other alternative tests for drug metabolising enzyme induction, when such tests arise, it is recommended that they meet the same level of development as for the collagen gel sandwich long-term hepatocyte system. Those tests which do so should begin the prevalidation and validation process.
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In Vitro Methods in the Prediction of Kinetics of Drugs: Focus on Drug Metabolism

Hannu Raunio, Päivi Taavitsainen, Paavo Honkakoski, Risto Juvonen and Olavi Pelkonen

The absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of a candidate drug influence its final clinical success. These properties have traditionally been evaluated by using various in vivo animal approaches, but recently, a number of in vitro and in silico methods have been introduced to determine key ADMET features. Basic events, such as absorption through the gut wall, binding to plasma proteins, active and passive transfer through the blood–brain barrier, and various metabolic parameters, can now be screened with rapid in vitro and computer modelling methods. The focus in this short review is on the basic in vitro and in silico methods that are used for studying the metabolism properties of new drug molecules.
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2017-01-09T06:33:08+00:00 Tags: , , |