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[Determination of finasteride in human plasma by HPLC-MS]
Xiang-yang Li1, Li Ding, Li-min Li
1Department of Pharmacology, Qinghai Medical College, Xining 810001, China. qhmclxy@163.com
Aim:
To develop an HPLC-MS assay for determination of finasteride in human plasma and to investigate the bioequivalence in healthy volunteers.
Methods:
After alkalization with sodium hydroxide, plasma was extracted with ethyl acetate and separated using a C18 column with a mobile phase of methanol-water (85:15). LC-ESI-MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 395 for finasteride and m/z 407 for the IS. The fragmentor voltage was 120 V. A randomized crossover design was performed in 20 healthy volunteers. In the two study periods, a single 10 mg dose of each tablet was administered to each volunteer.
Results:
Calibration curves were linear over the range 1-200 micrograms.L-1 (r = 0.9986). The limit of determination for finasteride in plasma was 0.05 microgram.L-1. The recovery of finasteride from plasma was in the range of 85.9%-98.7%. The results of variance analysis and two one-side t-test showed that there was no significant difference between the two formulations in the AUC and Cmax.
Conclusion:
The assay was proved to be sensitive, accurate and convenient. The two formulations were bioequivalent.