Green stability indicating RP- HPLC method for simultaneous estimation of Silodosin and Tadalafil development validation and comparative evaluation using one way ANOVA

Abstract

A novel, cost-effective, and stability-indicating isocratic RP-HPLC method was developed for the simultaneous quantification of Silodosin and Tadalafil in a synthetic mixture containing their degradation products. The method aimed to ensure sensitive, accurate, and reliable estimation of both APIs for routine quality control and stability testing. Chromatographic separation was achieved on an Inertsil C18 column using a mobile phase of phosphate buffer and methanol (34:66, v/v) at a flow rate of 1.0 mL/min with detection at 220 nm. Silodosin and Tadalafil eluted at approximately 3.810 and 10.165 min, respectively. The method exhibited excellent linearity over 40–120 µg/mL (SLD) and 25–75 µg/mL (TDF), with correlation coefficients of 0.9983 for both drugs. Accuracy studies showed recovery between 99.34 and 100.98% for SLD and 98.51–99.78% for TDF. Precision, repeatability, and robustness results were within acceptable limits (%RSD < 2%). DL/QL values were in the nanogram range, confirming high sensitivity. Forced degradation studies demonstrated that all degradation products were well resolved from the parent drugs, confirming the stability-indicating capability of the method. To strengthen method reliability, one-way ANOVA was applied to compare assay values across degradation conditions. No statistically significant differences (p > 0.05) were observed, confirming method consistency under stress. Additionally, the performance of the developed method was statistically compared with a previously published RP-HPLC method (Research Journal of Pharmacy and Technology, 2025). ANOVA demonstrated that the present method offers comparable or superior analytical performance, supporting its enhanced precision, sensitivity, and stability-indicating efficiency. The validated RP-HPLC method meets ICH Q2(R2) requirements and proves robust, accurate, sensitive, and environmentally sustainable, as reflected by greenness assessment tools (GAPI, AGREE, AGREEprep, BAGI). The statistical comparison with an existing reported method further highlights the analytical advantage and reliability of the developed method for simultaneous quantification of Silodosin and Tadalafil in synthetic mixtures.