Spectrophotometric and Stability Indicating RP-HPLC-PDA Method for Simultaneous Determination of Finasteride and Tamsulosin in Combined Tablet Dosage Form

Simple, accurate, precise, and sensitive ultraviolet spectrophotometric and stability indicating reversed phase high performance liquid chromatographic methods for simultaneous estimation of Tamsulosin and Finasteride in combined tablet dosage form have been developed and validated. The spectroscopic method employs an absorbance correction method using 228 and 246 nm as two wavelengths for estimation with methanol as solvent. Beer's law is obeyed in the concentration range of 2-10 and 25-125 μg/mL for Tamsulosin and Finasteride respectively. The reversed phase high performance liquid chromatographic separation was achieved on a Waters Symmetry C₁₈ column (250 mm×4.6 mm, 5.0 μ particle size) using Methanol:Water:THF (75:15:10 v/v/v) mobile phase. Trifluoroacetic was used to adjusted pH to 3.7 with, flow rate was 0.7 mL/min and column temperature was maintained at 32°C. Quantification was achieved with PDA detector at 275 nm over the concentration range of 50 to 400 μg/mL for Finasteride and 4 to 44 μg/mL for Tamsulosin. Both methods have been successfully applied for the analysis of the drugs in a pharmaceutical formulation. Results of analysis were validated statistically and by recovery studies.