Chromatographic methods for determination of finasteride and tamsulosin hydrochloride and in presence of finasteride degradation product

Abstract

Two sensitive and selective chromatographic methods were developed for determination of finasteride and tamsulosin hydrochloride in bulk powder and a pharmaceutical formulation. The first method was based on high-performance liquid chromatography (HPLC) separation of the cited drugs in the presence of the acid degradation product of finasteride. The separation was achieved using a C18 column (300 mm × 3.9 mm; 10-μm particle size) and a mobile phase consisting of 0.04 M ortho-phosphoric acid (pH 3.5 ± 0.2 adjusted with triethylamine) and acetonitrile (50:50, v/v). Quantification was achieved with ultraviolet (UV) detection at 215 nm. Linearity was in the range of 10.00–110.00 μg/mL and 2.00–44.00 μg/mL for finasteride and tamsulosin hydrochloride, respectively. Thin-layer chromatography (TLC)–densitometric method was achieved on an aluminum plates pre-coated with silica gel 60 F254 using toluene–ethanol–diethylamine (8:2:1.5, by volume) as eluent, and the RF values of tamsulosin hydrochloride and finasteride were 0.57 and 0.64, respectively. Quantification was achieved with UV detection at 250 nm for finasteride and 280 nm for tamsulosin hydrochloride. Linearity was in the range of 1.00–40.00 and 0.2.00–20.00 μg per spot for finasteride and tamsulosin hydrochloride, respectively. The results obtained were validated according to the International Conference on Harmonisation (ICH) guidelines. A statistical comparison between the obtained results and the results of a reported method was carried out.