title: Determination of finasteride in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry with flow rate gradient.
abstract: In this study, an attempt was made to describe and validate liquid chromatography-electrospray ionization tandem mass spectrometry as a fast, sensitive and reproducible method for determining finasteride in human plasma. Finasteride and internal standard (pantoprazole) were extracted by liquid-liquid extraction using methyl tert-butyl ether. Separation was performed by using a flow rate gradient on a reverse phase C18 column at 25°C. The mobile phase consisted of methanol-water (70:30, v/v) containing 0.5% anhydrous formic acid. The protonated analytes were quantitated in positive ionization by multiple reaction monitoring in mass spectrometry. The mass transitions are m/z 373.4→305.3 and 384.1→200.0 for finasteride and pantoprazole, respectively. The method had a run time of 3.6 min and a linear calibration curve at a range of 0.2-100 ng mL(-1) (r2=0.9958). The lower limit of quantification was 0.2 ng mL(-1). The extraction recoveries of finasteride from the biological matrix were more than 82.7%, and the intra- and inter-day precision of the assay at four concentrations were 2.4-8.0% with an accuracy of 94.3-105.8%. The developed method requires less plasma (0.1 mL), but has high sensitivity. The validated method has been successfully used to analyze human plasma samples in pharmacokinetic or bioequivalence studies.
authors.affiliation: School of Pharmacy, Nanjing Medical University, Nanjing, 210029, People's Republic of China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Yuan
authors.forename: Meijuan
authors.initials: M
authors.lastname: Ding
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.forename: Jinhui
authors.initials: J
authors.lastname: Xu
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wu
authors.forename: Jing
authors.initials: J
authors.lastname: Feng
authors.forename: Fei
authors.initials: F
authors.lastname: Shen
authors.forename: Xuemin
authors.initials: X
authors.lastname: Zhou
mesh_terms: D058891:5-alpha Reductase Inhibitors / Q000097:blood* / Q000493:pharmacokinetics; D000284:Administration, Oral; D000328:Adult; D002853:Chromatography, Liquid / Q000379:methods*; D018120:Finasteride / Q000097:blood* / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods; D013810:Therapeutic Equivalency; D055815:Young Adult
chemical_list: D058891:5-alpha Reductase Inhibitors; D018120:Finasteride