Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/14383
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Type: Journal article
Title: Determination of in vivo absorption, metabolism, and transport of drugs by the human intestinal wall and liver with a novel perfusion technique
Author: von Richter, O.
Greiner, B.
Fromm, M.
Fraser, R.
Omari, T.
Barclay, M.
Dent, J.
Somogyi, A.
Eichelbaum, M.
Citation: Clinical Pharmacology and Therapeutics, 2001; 70(3):217-227
Publisher: Mosby Inc
Issue Date: 2001
ISSN: 0009-9236
1532-6535
Statement of
Responsibility: 
Oliver von Richter, Bernd Greiner, Martin F. Fromm, Robert Fraser, Taher Omari, Murray L. Barclay, John Dent, Andrew A. Somogyi and Michel Eichelbaum
Abstract: Background and Aims: The contribution of the gastrointestinal tract in comparison with the liver for the low and variable bioavailability of orally administered drugs is still poorly understood. Here we report on a new intestinal perfusion technique for the direct assessment of absorption, metabolism, and transport of drugs by the intestinal wall. Methods: In 6 healthy volunteers a multilumen perfusion catheter was used to generate a 20-cm isolated jejunal segment that was perfused with 80 mg verapamil. Simultaneously, 5 mg [2H7]verapamil was given intravenously. Blood, perfusate, and bile samples were analyzed for parent verapamil and its major metabolites. Results: The mean fraction of the verapamil dose absorbed from the 20-cm segment was 0.76 but substantial interindividual variability (0.51-0.96) was shown. Bioavailability was low (19.3%). The intestinal wall contributed to the same extent as the liver to extensive first-pass metabolism (mean extraction ratio, 0.49 versus 0.48). Substantial transport of verapamil metabolites from the systemic circulation via the enterocytes into the intestinal lumen was observed. Compared with biliary excretion, intestinal secretion into a 20-cm jejunal segment contributed to drug elimination to a similar extent. Conclusion: First-pass metabolism by the intestinal wall is extensive and contributes to the same extent as the liver to low bioavailability of some drugs such as verapamil. Moreover, intestinal secretion is as important as biliary excretion for the elimination of metabolites.
Keywords: Intestinal Mucosa
Liver
Bile
Humans
Verapamil
Calcium Channel Blockers
Pharmaceutical Preparations
Area Under Curve
Perfusion
Biological Transport
Biological Availability
Intestinal Absorption
Algorithms
Adult
Middle Aged
Male
Description: Copyright © 2001 by the American Society for Clinical Pharmacology and Therapeutics.
DOI: 10.1067/mcp.2001.117937
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