title: In vitro inhibitory effects of Wen-pi-tang-Hab-Wu-ling-san on human cytochrome P450 isoforms.
abstract: OBJECTIVE
  Although Wen-pi-tang-Hab-Wu-ling-san (WHW), an oriental herbal medicine, has been prescribed for the treatment of chronic renal failure (CRF) in Korean clinics, no studies regarding WHW-drug interactions had been reported. The purpose of this study was to evaluate the possibility that WHW inhibits the catalytic activities of major cytochrome P450 (CYP) isoforms.
  
  
  METHODS
  The abilities of various WHW extracts to inhibit phenacetin O-de-ethylation (CYP1A2), tolbutamide 4-methylhydroxylation (CYP2C9), omeprazole 4'-hydroxylation (CYP2C19), dextromethorphan O-demethylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1) and midazolam 1-hydroxylation (CYP3A4) were assessed using human liver microsomes.
  
  
  CONCLUSIONS
  WHW extract at concentrations up to 100 μm showed negligible inhibition of the six CYP isoforms tested (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4), with apparent IC(50) values (concentration of the inhibitor causing 50% inhibition of the original enzyme activity) of 817.5, 601.6, 521.7, 310.2, 342.8 and 487.0 μg/mL, respectively.
  
  
  CONCLUSIONS
  Our in vitro findings suggest that WHW extract at concentrations corresponding to a clinically recommended dosage range has no notable inhibitory effects on CYP isoforms. Therefore, we believe that WHW extract may be free of drug-herb interactions when co-administered with other medicines. However, in vivo human studies are needed to confirm these results.
authors: Department of Biomedical Science, Kyungpook National University Graduate School, Junggu, Daegu, South Korea.
authors: H W
authors: HW
authors: Lee
authors: D W
authors: DW
authors: Kim
authors: P B
authors: PB
authors: Phapale
authors: M-S
authors: MS
authors: Lim
authors: J
authors: J
authors: Park
authors: J J
authors: JJ
authors: Seo
authors: K M
authors: KM
authors: Park
authors: Y-K
authors: YK
authors: Park
authors: Y-R
authors: YR
authors: Yoon
mesh_terms: D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage / Q000494:pharmacology*; D041743:Herb-Drug Interactions; D006801:Humans; D066298:In Vitro Techniques; D020128:Inhibitory Concentration 50; D007527:Isoenzymes; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D056910:Republic of Korea
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D004365:Drugs, Chinese Herbal; D007527:Isoenzymes; C521629:Wen-pi-tang-Hab-Wu-ling-san; D003577:Cytochrome P-450 Enzyme System