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Your search keyword '"Rooswinkel RW"' showing total 3 results
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3 results on '"Rooswinkel RW"'

1. Inhibition and stimulation of intestinal and hepatic CYP3A activity: studies in humanized CYP3A4 transgenic mice using triazolam.

Author

van Waterschoot RA, Rooswinkel RW, Sparidans RW, van Herwaarden AE, Beijnen JH, and Schinkel AH

Subjects
Administration, Oral, Animals, Antineoplastic Agents administration & dosage, Cytochrome P-450 CYP3A genetics, Cytochrome P-450 CYP3A Inhibitors, Cytochrome P-450 Enzyme Inhibitors, Cytochrome P-450 Enzyme System deficiency, Cytochrome P-450 Enzyme System genetics, Drug Interactions, Enzyme Activators administration & dosage, Enzyme Inhibitors administration & dosage, Gefitinib, Humans, Hydroxylation, Intestines drug effects, Ketoconazole administration & dosage, Liver drug effects, Male, Mice, Mice, Knockout, Mice, Transgenic, Microsomes enzymology, Quinazolines administration & dosage, Species Specificity, Substrate Specificity, Triazolam administration & dosage, Cytochrome P-450 CYP3A metabolism, Cytochrome P-450 Enzyme System metabolism, Intestines enzymology, Liver enzymology, Triazolam pharmacokinetics
Abstract

CYP3A4 is an important determinant of drug-drug interactions. In this study, we evaluated whether cytochrome P450 3A knockout mice [Cyp3a(-/-)] and CYP3A4 transgenic (CYP3A4-Tg) mice can be used to study drug-drug interactions in the liver and intestine. Triazolam was used as a probe drug because it is a highly specific CYP3A substrate and not a P-glycoprotein substrate. Triazolam metabolism was profoundly reduced in Cyp3a(-/-) mice both in vitro and in vivo. In vitro studies revealed clear species differences in humans and mice, but triazolam metabolism in microsomes derived from CYP3A4-Tg "humanized" mice closely resembled that in human microsomes. It is interesting to note that studies with tissue-specific CYP3A4-Tg mice revealed that intestinal CYP3A4 has a major impact on oral triazolam exposure, whereas the effect of hepatic CYP3A4 was limited. To mimic a drug-drug interaction, we coadministered triazolam with the prototypical CYP3A inhibitor ketoconazole, which increased triazolam exposure in all the CYP3A-proficient mouse strains but not in Cyp3a(-/-) mice. We further found that the anticancer drug gefitinib is a potent stimulator of 1'-OH triazolam formation in vitro. It is noteworthy that we could also show in vivo stimulation of triazolam metabolism by gefitinib, resulting in a lower oral triazolam exposure. To our knowledge, this is the first in vivo example of direct stimulation of CYP3A4 activity after oral drug administration. Overall, this study illustrates how Cyp3a(-/-) and CYP3A4-Tg mice can be used to study drug-drug interactions. The data clarify that for drugs that are not P-glycoprotein substrates, intestinal metabolism also can be more important than hepatic metabolism after oral administration.

Published
2009
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2. Intestinal cytochrome P450 3A plays an important role in the regulation of detoxifying systems in the liver.

Author

van Waterschoot RA, Rooswinkel RW, Wagenaar E, van der Kruijssen CM, van Herwaarden AE, and Schinkel AH

Subjects
Animals, Cytochrome P-450 Enzyme System genetics, Cytochrome P-450 Enzyme System metabolism, Cytochrome P450 Family 2, Diet, Gene Expression Regulation, Enzymologic physiology, Humans, Mice, Mice, Knockout, Pregnane X Receptor, Receptors, Steroid genetics, Cytochrome P-450 CYP3A genetics, Cytochrome P-450 CYP3A metabolism, Intestines enzymology, Liver enzymology
Abstract

CYP3A4 is an important xenobiotic metabolizing enzyme. We previously found that CYP2C55 is highly up-regulated in Cyp3a(-/-) mice. Here, we have further investigated the mechanism of regulation of CYP2C55 and other detoxifying systems in Cyp3a(-/-) mice. Induction studies with prototypical inducers demonstrated an important role for the nuclear receptors PXR and CAR in the up-regulation of CYP2C55. Subsequent diet-switch experiments revealed that food-derived xenobiotics are primarily responsible for the increased induction of CYP2C55, as well as of several other primary detoxifying systems in Cyp3a(-/-) mice. Our data suggest that CYP3A normally metabolizes food-derived activators of PXR and/or CAR, explaining the increased levels of such activators in Cyp3a(-/-) mice and subsequent up-regulation of a range of detoxifying systems. Interestingly, our studies with tissue-specific CYP3A4 transgenic Cyp3a(-/-) mice revealed that not only hepatic but also intestinal expression of CYP3A4 could reduce the hepatic expression of detoxifying systems to near wild-type levels. Apparently, intestinal CYP3A4 can limit the hepatic exposure to food-derived activators of nuclear receptors, thereby regulating the expression of a range of detoxifying systems in the liver. This broad biological effect further emphasizes the importance of intestinal CYP3A activity and could have profound implications for the prediction of drug exposure.

Published
2009
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3. Effects of cytochrome P450 3A (CYP3A) and the drug transporters P-glycoprotein (MDR1/ABCB1) and MRP2 (ABCC2) on the pharmacokinetics of lopinavir

Author

van Waterschoot, RAB, ter Heine, R, Wagenaar, E, van der Kruijssen, CMM, Rooswinkel, RW, Huitema, ADR, Beijnen, JH, and Schinkel, AH

Subjects
Male, Ritonavir, Biological Availability, Mice, Inbred Strains, Mice, Transgenic, HIV Protease Inhibitors, Pyrimidinones, Research Papers, Lopinavir, Multidrug Resistance-Associated Protein 2, Intestines, Mice, Dogs, Liver, Animals, Cytochrome P-450 CYP3A, Humans, Drug Interactions, ATP Binding Cassette Transporter, Subfamily B, Member 1, Intestinal Mucosa, Multidrug Resistance-Associated Proteins
Abstract

Lopinavir is extensively metabolized by cytochrome P450 3A (CYP3A) and is considered to be a substrate for the drug transporters ABCB1 (P-glycoprotein) and ABCC2 (MRP2). Here, we have assessed the individual and combined effects of CYP3A, ABCB1 and ABCC2 on the pharmacokinetics of lopinavir and the relative importance of intestinal and hepatic metabolism. We also evaluated whether ritonavir increases lopinavir oral bioavailability by inhibition of CYP3A, ABCB1 and/or ABCC2.Lopinavir transport was measured in Madin-Darby canine kidney cells expressing ABCB1 or ABCC2. Oral lopinavir kinetics (+/- ritonavir) was studied in mice with genetic deletions of Cyp3a, Abcb1a/b and/or Abcc2, or in transgenic mice expressing human CYP3A4 exclusively in the liver and/or intestine.Lopinavir was transported by ABCB1 but not by ABCC2 in vitro. Lopinavir area under the plasma concentration - time curve (AUC)(oral) was increased in Abcb1a/b(-/-) mice (approximately ninefold vs. wild-type) but not in Abcc2(-/-) mice. Increased lopinavir AUC(oral) (2000-fold) was observed in cytochrome P450 3A knockout (Cyp3a(-/-)) mice compared with wild-type mice. No difference in AUC(oral) between Cyp3a(-/-) and Cyp3a/Abcb1a/b/Abcc2(-/-) mice was observed. CYP3A4 activity in intestine or liver, separately, reduced lopinavir AUC(oral) (100-fold), compared with Cyp3a(-/-) mice. Ritonavir markedly increased lopinavir AUC(oral) in all CYP3A-containing mouse strains.CYP3A was the major determinant of lopinavir pharmacokinetics, far more than Abcb1a/b. Both intestinal and hepatic CYP3A activity contributed importantly to low oral bioavailability of lopinavir. Ritonavir increased lopinavir bioavailability primarily by inhibiting CYP3A. Effects of Abcb1a/b were only detectable in the presence of CYP3A, suggesting saturation of Abcb1a/b in the absence of CYP3A activity.

Published
2010

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