title: Determination of atomoxetine and its metabolites in conventional and non-conventional biological matrices by liquid chromatography-tandem mass spectrometry.
abstract: A procedure based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) is described for determination of atomoxetine (ATX) and its metabolites 4-hydroxyatomoxetine (4-OH-ATX) and N-des-methylatomoxetine (N-des-ATX) in plasma, urine, oral fluid and sweat using duloxetine as internal standard. Analytes were extracted from 0.5 mL biological fluids and sweat patch with 2 mL aliquots of tert-butyl methyl ether. The organic layer was evaporated and redissolved in mobile phase. Chromatographic separation was carried out on reverse-phase column and an isocratic mobile phase formed by 40% water and 60% 5mM ammonium acetate, 47.2 mM formic acid, 4 mM trifluoroacetic acid in acetonitrile-water (85:15, v/v) at a flow rate of 0.5 mL/min. Separated analytes were identified and quantified by positive electrospray ionization tandem mass spectrometry and in multiple reaction monitoring acquisition mode. Limits of quantifications for the three analytes were 0.5 ng/mL plasma and oral fluid, 10 ng/mL urine and 1 ng/patch using 0.5 mL biological fluids or one sweat-patch per assay. Calibration curves were linear over the calibration ranges with r²>0.99. At three concentrations spanning the linear dynamic range of the assay, mean recoveries in different biological matrices were always higher than 65%. This method was applied to therapeutic monitoring of ATX and its metabolites 4-OH-ATX and N-des-ATX in conventional and non-conventional biological matrices from individuals in drug treatment.
authors.affiliation: Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Emilia
authors.initials: E
authors.lastname: Marchei
authors.forename: Esther
authors.initials: E
authors.lastname: Papaseit
authors.forename: Oscar Q
authors.initials: OQ
authors.lastname: Garcia-Algar
authors.forename: Magi
authors.initials: M
authors.lastname: Farrè
authors.forename: Roberta
authors.initials: R
authors.lastname: Pacifici
authors.forename: Simona
authors.initials: S
authors.lastname: Pichini
mesh_terms: D000293:Adolescent; D018759:Adrenergic Uptake Inhibitors / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D000069445:Atomoxetine Hydrochloride; D002853:Chromatography, Liquid / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D057230:Limit of Detection; D008297:Male; D011437:Propylamines / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D012463:Saliva / Q000378:metabolism*; D013542:Sweat / Q000378:metabolism*; D053719:Tandem Mass Spectrometry / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D018759:Adrenergic Uptake Inhibitors; D011437:Propylamines; D000069445:Atomoxetine Hydrochloride