Dataset Information

Drug interactions of thalidomide with midazolam and cyclosporine A: heterotropic cooperativity of human cytochrome P450 3A5.

ABSTRACT: There is growing clinical interest of thalidomide because of its immunomodulatory and antiangiogenic properties, despite its teratogenicity. However, little information about thalidomide has been reported regarding its precise effects on drug-metabolizing enzymes. We investigated the effects of thalidomide on cytochrome P450 (P450) enzymes in human liver microsomes to clarify the potential for possible drug interactions. Thalidomide inhibited S-mephenytoin 4'-hydroxylation activities of recombinant P450 2C19 and human liver microsomes: the apparent concentration of thalidomide producing 50% inhibition was approximately 270 microM for P450 2C19. Midazolam 4-hydroxylation activities were suppressed by thalidomide, but activities of 1'-hydroxylation and total midazolam oxidation and testosterone 6beta-hydroxylation were enhanced in the presence of thalidomide. Recombinant P450 3A5 was found to have altered kinetics at clinically relevant concentrations of thalidomide (10-30 microM). P450 3A4 was also affected, but only at higher thalidomide concentrations. Enhanced midazolam hydroxylation by thalidomide was also seen in liver microsomal samples harboring the CYP3A5*1 allele. Similarly enhanced rates of cyclosporine A clearance were observed in P450 3A5 and liver microsomes expressing P450 3A5 in the presence of thalidomide. A proposed effector constant for thalidomide corresponded roughly to its clinical plasma levels. Docking studies with a P450 3A5 homology model, based on the published structure of P450 3A4, revealed close interaction between thalidomide and the heme of P450 3A5. The present results suggest that total midazolam metabolism or cyclosporine A clearance may be increased by thalidomide in a dose-dependent manner. Unexpected drug interactions involving thalidomide might occur via heterotropic cooperativity of polymorphic P450 3A5.

SUBMITTER: Okada Y

PROVIDER: S-EPMC2719675 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Drug interactions of thalidomide with midazolam and cyclosporine A: heterotropic cooperativity of human cytochrome P450 3A5.

Okada Yusuke Y Murayama Norie N Yanagida Chihiro C Shimizu Makiko M Guengerich F Peter FP Yamazaki Hiroshi H

Drug metabolism and disposition: the biological fate of chemicals 20081023 1

There is growing clinical interest of thalidomide because of its immunomodulatory and antiangiogenic properties, despite its teratogenicity. However, little information about thalidomide has been reported regarding its precise effects on drug-metabolizing enzymes. We investigated the effects of thalidomide on cytochrome P450 (P450) enzymes in human liver microsomes to clarify the potential for possible drug interactions. Thalidomide inhibited S-mephenytoin 4'-hydroxylation activities of recombin ...[more]

PMID: 18948377

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Project description:An investigational anticancer agent that contains a thiophene moiety, 3-[(quinolin-4-ylmethyl)-amino]-N-[4-trifluoromethox)phenyl] thiophene-2-carboxamide (OSI-930), was tested to investigate its ability to modulate the activities of several cytochrome P450 enzymes. Results showed that OSI-930 inactivated purified, recombinant cytochrome P450 (P450) 3A4 in the reconstituted system in a mechanism-based manner. The inactivation was dependent on cytochrome b(5) and required NADPH. Catalase did not protect against the inactivation. No inactivation was observed in studies with human 2B6, 2D6, or 3A5 either in the presence or in the absence of b(5). The inactivation of 3A4 by OSI-930 was time- and concentration-dependent. The inactivation of the 7-benzyloxy-4-(trifluoromethyl)coumarin catalytic activity of 3A4 was characterized by a K(I) of 24 μM and a k(inact) of 0.04 min(-1). This K(I) is significantly greater than the clinical OSI-930 C(max) of 1.7 μM at the maximum tolerated dose, indicating that clinical drug interactions of OSI-930 via this pathway are not likely. Spectral analysis of the inactivated protein indicated that the decrease in the reduced CO spectrum at 450 nm was comparable to the amount of inactivation, thereby suggesting that the inactivation was primarily due to modification of the heme. High-pressure liquid chromatography (HPLC) analysis with detection at 400 nm showed a loss of heme comparable to the activity loss, but a modified heme was not detected. This result suggests either that the heme must have been modified enough so as not to be observed in a HPLC chromatograph or, possibly, that it was destroyed. The partition ratio for the inactivation of P450 3A4 was approximately 23, suggesting that this P450 3A4-mediated pathway occurs with approximately 4% frequency during the metabolism of OSI-930. Modeling studies on the binding of OSI-930 to the active site of the P450 3A4 indicated that OSI-930 would be oriented properly in the active site for oxidation of the thiophene sulfur to give the sulfoxide, which has previously been shown to be a significant metabolite of OSI-930. Because OSI-930 is an inactivator of P450 3A4 but does not exhibit any effect on P450 3A5 activity under the same conditions, it may be an appropriate probe for exploring unique aspects of these two very similar P450s.

Dataset Information

Drug interactions of thalidomide with midazolam and cyclosporine A: heterotropic cooperativity of human cytochrome P450 3A5.

Publications

Drug interactions of thalidomide with midazolam and cyclosporine A: heterotropic cooperativity of human cytochrome P450 3A5.

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