Received for publication May 23, 2006.
Revised August 10, 2006.
Accepted for publication August 10, 2006.

Innovative methods to study human intestinal drug metabolism in vitro: precision-cut slices compared with Ussing chamber preparations

Abstract

Predictive in vitro methods to investigate drug metabolism in the human intestine using intact tissue are of high importance. Therefore, we studied the metabolic activity of human small intestinal and colon slices and compared it with the metabolic activity of the same human intestinal segments using the Ussing chamber technique. The metabolic activity was evaluated using substrates to both phase I and phase II reactions: testosterone, 7-hydroxycoumarin (7HC) and a cocktail of CYP substrates (midazolam, diclofenac, coumarin and bufuralol). In slices of human proximal jejunum, the metabolic activity of several CYP mediated and conjugation reactions remained constant up to 4 h of incubation. In the colon slices, conjugation rates were virtually equal to those in small intestine; while CYP mediated conversions occurred much slower. In both organs, morphological evaluation and ATP content implied tissue integrity within this period. CYP conversions using the Ussing chamber technique showed that the metabolic rate (sum of metabolites measured in apical, basolateral and tissue compartments) was constant up to 3 h. For 7HC conjugations, the metabolic rate remained constant up to 4 h. The distribution of the metabolites in the compartments differed between the substrates. Overall, metabolic rates were surprisingly similar in both techniques and appear similar to or even higher than in liver. In conclusion, this study shows that both human intestinal precision-cut slices as well as Ussing chamber preparations provide useful tools for in vitro biotransformation studies.

Key words: gastrointestinal cytochrome P450, glucuronidation, human CYP enzymes, sulfate conjugation

This article has been cited by other articles:

				E. G. van de Kerkhof, I. A. M. de Graaf, A.-L. B. Ungell, and G. M. M. Groothuis Induction of Metabolism and Transport in Human Intestine: Validation of Precision-Cut Slices as a Tool to Study Induction of Drug Metabolism in Human Intestine in Vitro Drug Metab. Dispos., March 1, 2008; 36(3): 604 - 613. [Abstract] [Full Text] [PDF]

				E. G. van de Kerkhof, I. A. M. de Graaf, M. H. de Jager, and G. M. M. Groothuis Induction of Phase I and II Drug Metabolism in Rat Small Intestine and Colon in Vitro Drug Metab. Dispos., June 1, 2007; 35(6): 898 - 907. [Abstract] [Full Text] [PDF]