Published:Journal of Chromatographic Science,
ISSN 0021-9665 Volume
46, Number 4, April 2008, pp. 356-361
?Development and Validation of an LC–MS
Assay for Finasteride and its Application to Prostate Cancer
Prevention Trial Sample Analysis
?Xiaohong Chen1, Erin R. Gardner2, Douglas K.
Price3, and William D. Figg1, 1Clinical Pharmacology Program, Center for Cancer Research, National
Cancer Institute, Bethesda, MD 20892, USA; 2Clinical Pharmacology
Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, MD 21702,
USA; 3Molecular Pharmacology Section, Center for Cancer Research,
National Cancer Institute, Bethesda, MD 20892, USA
?An analytical method is developed and validated
for the quantitative determination of finasteride, a potent 5
a–reductase inhibitor, in human plasma. Calibration curves
are linear in the concentration range of 1 to 100 ng/mL. Sample
pretreatment involves a liquid–liquid extraction with ethyl
acetate using 0.2 mL aliquots of plasma. Finasteride and the
internal standard (beclomethasone) are separated on a Waters
Symmetry Shield RP18 column (50 × 2.1 mm, 3.5 µm) and
eluted using a gradient mobile phase composed of acetonitrile
and 10mM ammonium acetate with 0.1% formic acid. The column eluant
is monitored by mass spectrometry with electrospray ionization.
A complete validation of the method is performed. For quality
control samples at three different concentrations that were analyzed
in quintuplicate, on six separate occasions, the accuracy and
precision range from 95.2% to 101% and 3.4% to 7.3%, respectively.
The developed method is subsequently applied to measure the steady
state finasteride concentration of patients who participated
in the Prostate Cancer Prevention Trial.
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