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

• Published in: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Analytical technologies in the biomedical and life sciences, 2010-06, Vol.878 (20), p.1718-1723
• Main Authors: Phapale, Prasad B., Lee, Hae Won, Lim, Mi-sun, Kim, Eun-Hee, Kim, Sung-Doo, Park, Jeonghyeon, Lee, Miran, Hwang, Sung-Kyu, Yoon, Young-Ran
• Format: Article
• Language: English
• Subjects: Adult; Analysis; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Chromatography, High Pressure Liquid - methods; Evaporation; Finasteride; Finasteride - blood; Finasteride - pharmacokinetics; Fundamental and applied biological sciences. Psychology; General pharmacology; Human; Human plasma; Humans; Ion pairs; Liquid-liquid extraction; Male; Mass spectrometers; Medical sciences; Method validation; Monitoring; Pharmacokinetic study; Pharmacology. Drug treatments; Recovery; Standard deviation; Tandem Mass Spectrometry - methods; UPLC–MS/MS
• ISSN: 1570-0232; 1873-376X
• DOI: 10.1016/j.jchromb.2010.04.029

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 performed 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 °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.