title: A comparison of 4β-hydroxycholesterol : cholesterol and 6β-hydroxycortisol : cortisol as markers of CYP3A4 induction.
abstract: OBJECTIVE
  To compare plasma 4β-hydroxycholesterol : cholesterol with urinary 6β-hydroxycortisol : cortisol as markers of cytochrome P4503A4 activity before and after treatment with rifampicin for 2 weeks.
  
  
  METHODS
  6β-hydroxycortisol and cortisol were determined by liquid chromatography tandem mass spectrometry and 4β-hydroxycholesterol was determined by gas chromatography-mass spectrometry in three groups of healthy volunteers.
  
  
  RESULTS
  Induction ratios for 6β-hydroxycortisol : cortisol were 1.8, 3.9 and 4.5 for 20 mg day(-1) , 100 mg day(-1) or 500 mg day(-1) of rifampicin, respectively. The corresponding ratios for 4β-hydroxycholesterol : cholesterol were 1.5, 2.4 and 3.8.
  
  
  CONCLUSIONS
  Plasma 4β-hydroxycholesterol : cholesterol gave similar induction ratios to urinary 6β-hydroxycortisol : cortisol.
authors.affiliation: Clinical Chemistry, Karolinska University Hospital, Huddinge, Sweden.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Mårde Arrhén
authors.forename: Hanna
authors.initials: H
authors.lastname: Nylén
authors.forename: Anita
authors.initials: A
authors.lastname: Lövgren-Sandblom
authors.forename: Kajsa P
authors.initials: KP
authors.lastname: Kanebratt
authors.forename: Katarina
authors.initials: K
authors.lastname: Wide
authors.forename: Ulf
authors.initials: U
authors.lastname: Diczfalusy
mesh_terms: D000904:Antibiotics, Antitubercular / Q000493:pharmacokinetics* / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism*; D002784:Cholesterol / Q000097:blood*; D002853:Chromatography, Liquid; D051544:Cytochrome P-450 CYP3A / Q000096:biosynthesis*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000652:urine*; D006888:Hydroxycholesterols / Q000097:blood*; D008297:Male; D012293:Rifampin / Q000493:pharmacokinetics* / Q000494:pharmacology
chemical_list: D000904:Antibiotics, Antitubercular; D015415:Biomarkers; D006888:Hydroxycholesterols; C099828:cholest-5-ene-3,4-diol; C001380:6 beta-hydroxycortisol; D002784:Cholesterol; D051544:Cytochrome P-450 CYP3A; D012293:Rifampin; D006854:Hydrocortisone