Rapid determination of finasteride in human plasma by UPLC-MS/MS and its application to clinical pharmacokinetic study

A rapid, specific, and sensitive method utilizing reversed-phase ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed and validated to determine finasteride levels in human plasma The plasma samples were prepared by liquid-liquid extraction with ethyl acetate, evaporation, and reconstitution MS/MS analyses were per formed on a triple-quadrupole tandem mass spectrometer by monitoring protonated parent -> daughter ion pairs at m/z 373 -> 305 for finasteride and m/z 237 -> 194 for carbamazepine (internal standard, IS) The method was validated with respect to linearity, recovery, specificity, accuracy, precision, and stability The method exhibited a linear response from 0 1 to 30 ng/mL (r(2) > 0 998) The limit of quantitation for finasteride in plasma was 0 1 ng/mL The relative standard deviation (RSD) of intra- and inter-day measurements was less than 15% and the method was accurate within -6 0% to 2 31% at all quality-control levels The mean extraction recovery was higher than 83% for finasteride and 84% for the IS Plasma samples containing finasteride were stable under the three sets of conditions tested and the processed samples were stable up to 29 h in an autosampler at 5 degrees C Detection and quantitation of both analytes within 3 min make this method suitable for high-throughput analyses The method was successfully applied to a pharmacokinetic study of finasteride in healthy volunteers following oral administration (C) 2010 Elsevier B V All rights reserved