title: Automated on-line SPE LC-MS/MS method to quantitate 6beta-hydroxycortisol and cortisol in human urine: use of the 6beta-hydroxycortisol to cortisol ratio as an indicator of CYP3A4 activity.
abstract: A sensitive method for quantitation of urinary 6beta-hydroxycortisol (6beta-HC) and cortisol using on-line SPE and LC-MS/MS was developed and validated. Human urine samples were injected directly onto an on-line solid phase extraction apparatus, Prospekt-2, followed by HPLC separation and electrospray triple quadrupole LC-MS/MS detection. The inter-day precision for the 6beta-HC:cortisol ratio was 7-9%. The lower limit of quantitation was 1 and 0.2 ng/mL for 6beta-HC and cortisol, respectively. Using the method we observed a diurnal variation on the 6beta-HC:cortisol ratio in healthy volunteers with the maximal ratio observed in the 2-10 pm urine collection period.
authors.affiliation: Bristol-Myers Squibb Company, Clinical Discovery, P.O. Box 5400, Princeton, NJ 08543, USA. yuchen.barrett@bms.com
authors.forename: Yu Chen
authors.initials: YC
authors.lastname: Barrett
authors.forename: Billy
authors.initials: B
authors.lastname: Akinsanya
authors.forename: Shu-Ying
authors.initials: SY
authors.lastname: Chang
authors.forename: Ole
authors.initials: O
authors.lastname: Vesterqvist
mesh_terms: D001322:Autoanalysis; D001888:Boric Acids; D002853:Chromatography, Liquid / Q000379:methods*; D002940:Circadian Rhythm; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004355:Drug Stability; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000652:urine*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D009862:Online Systems / Q000295:instrumentation; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001888:Boric Acids; C001380:6 beta-hydroxycortisol; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; C032688:boric acid; D006854:Hydrocortisone