Drug Metabolism and Pharmacokinetics
Online ISSN : 1880-0920
Print ISSN : 1347-4367
ISSN-L : 1347-4367
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Effects of Continuous Ingestion of Green Tea or Grape Seed Extracts on the Pharmacokinetics of Midazolam
Masataka NISHIKAWANoritaka ARIYOSHIAkira KOTANIItsuko ISHIIHiroyoshi NAKAMURAHiromitsu NAKASAMayuri IDAHideo NAKAMURANobuhito KIMURAMaharu KIMURAAtsushi HASEGAWAFumiyo KUSUShigeru OHMORIKazuyoshi NAKAZAWAMitsukazu KITADA
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2004 Volume 19 Issue 4 Pages 280-289

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Abstract

  Limited systematic data on herb-drug interaction are available, despite many opportunities to concomitant use of herb with prescribed drugs. We investigated the effects of 15 herbal extracts in dietary supplements on CYP2C9, CYP2D6 and CYP3A4 activities in human liver microsomes. Strong inhibition of these CYP activities was found by the addition of green tea extracts (GTE) or grape seed extracts (GSE) in vitro. To examine the effects of these extracts on CYP3A activities in vivo, the pharmacokinetics of midazolam (MDZ) was analyzed in rats. Although single treatments with these extracts had negligible effects, 1 week of treatment with them resulted in a significant increase in the ke of intravenously administered MDZ, indicating the induction of CYP3A in the liver. In contrast, 1 week of treatment with GTE, but not GSE, caused a significant increase in the Cmax and AUC0-∞ of orally administered MDZ without change in the t1/2, suggesting a reduction in CYP3A activity in the small intestines. These studies indicate that subchronic ingestion of GTE or GSE may alter the pharmacokinetics of MDZ, and the effects of GTE on CYP3A activity appear opposite between liver and small intestine, which could not be predicted from in vitro experiments.

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© 2004 by The Japanese Society for the Study of Xenobiotics
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