[Show abstract] [Hide abstract]
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.
European Journal of Drug Metabolism and Pharmacokinetics 01/2011; 35(3-4):137-46. · 1.31 Impact Factor