title: Analysis of caffeine and paraxanthine in human saliva with ultra-high-performance liquid chromatography for CYP1A2 phenotyping.
abstract: Cytochrome P450 1A2 (CYP1A2) plays an important role in drug metabolism. Caffeine (CAF) is converted into paraxanthine (PX) by this enzyme and is used as a xenobiotic substrate to determine the CYP1A2 phenotype in humans. A method for the quantification of CAF and PX in saliva was developed using liquid-liquid extraction with ethyl acetate and analysis with ultra-high-performance liquid chromatography. Peaks from CAF, PX and internal standard were resolved within 6min. The method was validated from 0.05 to 5μgmL(-1) CAF and 0.025-2.5μgmL(-1) PX. Inter- and intra-day accuracies ranged from 91.2 to 107.2% with precisions <13.5%. The limits of detection were 0.16 and 0.63 ngmL(-1) for PX and CAF, respectively. PX/CAF concentration ratios from volunteers were 0.26-1.09 with mean ratios of 0.78±0.26 and 0.38±0.10 for regular and light/non-coffee drinkers, respectively.
authors.affiliation: Biomolecular Analysis, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Nan Yeun
authors.initials: NY
authors.lastname: Jordan
authors.affiliation: Biomolecular Analysis, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Jolet Y
authors.initials: JY
authors.lastname: Mimpen
authors.affiliation: Biomolecular Analysis, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Willie J M
authors.initials: WJ
authors.lastname: van den Bogaard
authors.affiliation: Biomolecular Analysis, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Frits M
authors.initials: FM
authors.lastname: Flesch
authors.affiliation: Biomolecular Analysis, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Michiel H M
authors.initials: MH
authors.lastname: van de Meent
authors.affiliation: Biomolecular Analysis, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands. Electronic address: j.sastretorano@uu.nl.
authors.forename: Javier Sastre
authors.initials: JS
authors.lastname: Torano
mesh_terms: D002110:Caffeine / Q000032:analysis* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019388:Cytochrome P-450 CYP1A2 / Q000145:classification* / Q000378:metabolism; D006801:Humans; D016014:Linear Models; D010641:Phenotype; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013806:Theophylline / Q000032:analysis* / Q000378:metabolism
chemical_list: D002110:Caffeine; D013806:Theophylline; C504573:CYP1A2 protein, human; D019388:Cytochrome P-450 CYP1A2; C021183:1,7-dimethylxanthine
keywords: CYP1A2; Caffeine; Paraxanthine; Phenotyping; Saliva; UHPLC