Abstract
Maraviroc is an anti-human immunodeficiency virus drug that acts by blocking viral entry into target cells. With use of ultra-performance liquid chromatography-mass spectrometry several monooxygenated, dioxygenated, and glucuronidated metabolites of maraviroc were identified both in vitro and in vivo. Characterization of the enzymes involved in the production of these metabolites determined that cytochrome P450 3A5 was the principal enzyme responsible for the formation of an abundant metabolite of maraviroc that resulted from oxygenation of the dichlorocyclohexane ring. For the formation of this metabolite, the Vmax values for CYP3A4 and CYP3A5 were 0.04 and 0.93 pmol · min−1 · pmol P450−1, and the Km values were 11.1 and 48.9 μM, respectively. Furthermore, human liver microsomes isolated from donors homozygous for the loss-of-function CYP3A5*3 allele exhibited a 79% decrease in formation of this metabolite compared with those homozygous for the wild-type CYP3A5*1 allele. To probe which divergent residues between CYP3A4 and CYP3A5 might play a role in the differential activities of these enzymes toward maraviroc, mutations were introduced into both enzymes and metabolism of maraviroc was measured. A CYP3A5 L57F mutant exhibited a 61% decrease in the formation of this metabolite, whereas formation by a CYP3A4 F57L mutant was increased by 337% compared with that of the wild type. Taken together, these data provide novel insights into the biotransformation of maraviroc as well as the potential role of CYP3A4 and CYP3A5 divergent residues in the enzymatic activities of these two highly homologous enzymes.
Footnotes
This work was supported by the Pharmaceutical Research and Manufacturers of America Foundation; National Institutes of Health HIV Prevention Trials Network [Grant 5UM1-AI068613]; National Institutes of Health National Center for Research Resources [Grant 1S10-RR027733]; and Pendleton Foundation Trust.
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
↵ The online version of this article (available at http://dmd.aspetjournals.org) contains supplemental material.
ABBREVIATIONS:
- HIV
- human immunodeficiency virus
- P450
- cytochrome P450
- SRS
- substrate recognition site
- UGT
- UDP-glucuronosyltransferase
- UPLC
- ultra-performance liquid chromatography
- MS
- mass spectrometry.
- Received July 30, 2012.
- Accepted August 24, 2012.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
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