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Mutual Inhibition between Carvedilol Enantiomers during Racemate Glucuronidation Mediated by Human Liver and Intestinal Microsomes

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Title: Mutual Inhibition between Carvedilol Enantiomers during Racemate Glucuronidation Mediated by Human Liver and Intestinal Microsomes
Authors: Takekuma, Yoh Browse this author →KAKEN DB
Yagisawa, Keiji Browse this author
Sugawara, Mitsuru Browse this author
Keywords: carvedilol
uridine 5'-diphosphate-glucuronosyl transferase
Issue Date: Feb-2012
Publisher: Pharmaceutical Society of Japan
Journal Title: Biological and Pharmaceutical Bulletin
Volume: 35
Issue: 2
Start Page: 151
End Page: 163
Publisher DOI: 10.1248/bpb.35.151
Abstract: Carvedilol is administered orally as a racemic mixture of R(+)- and S(-)-enantiomers for treatment of angina pectoris, hypertension and chronic heart failure. We have reported that enzyme kinetic parameters for carvedilol glucuronidation by human liver microsomes (HLM) differed greatly depending on the substrate form, namely, racemic carvedilol and each enantiomer. These phenomena were thought to be caused by mutual inhibition between carvedilol enantiomers during racemate glucuronidation. The aim of this study was to clarify the mechanism of these phenomena in HLM and human intestinal microsomes (HIM) and its relevance to uridine 5'-diphosphate (UDP)-glucuronosyl transferase (UGT) 1A1, UGT2B4 and UGT2B7, which mainly metabolize carvedilol directly in phase II enzymes. HLM apparently preferred metabolizing (S)-carvedilol to (R)-carvedilol in the racemate, but true activities of HLM for both glucuronidation were approximately equal. By determination of the inhibitory effects of (S)-carvedilol on (R)-carvedilol glucuronidation and vice versa, it was shown that (R)-carvedilol glucuronidation was more easily inhibited than was (S)-carvedilol glucuronidation. UGT2B7 was responsible for (S)-carvedilol glucuronidation in HLM. Ratios of contribution to (R)-carvedilol glucuronidation were approximately equal among UGT1A1, UGT2B4 and UGT2B7. However, enzyme kinetic parameters were different between the two lots of HLM used in this study, depending on the contribution ratio of UGT2B4, in which (R)-glucuronidation was much more easily inhibited by (S)-carvedilol than was (S)-glucuronidation by (R)-carvedilol. Meanwhile, HIM preferred metabolizing (R)-carvedilol, and this tendency was not different between the kinds of substrate form.
Type: article
Appears in Collections:薬学研究院 (Faculty of Pharmaceutical Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 武隈 洋

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