Development and Validation of a High-Performance Thin-Layer Chromatographic Method for the Simultaneous Estimation of Torsemide and Eplerenone by Quality by Design Approach

This paper includes the development of a novel, systematic, quality by design (QbD)-based high-performance thin-layer chromatography (HPTLC) method for the simultaneous estimation of torsemide and eplerenone. Chromatographic separation was carried out on aluminum-backed silica gel 60 F254 plates using toluene–ethyl acetate–glacial acetic acid (7:3:0.1, V/V) as the mobile phase. UV detection was carried out at 297 nm for torsemide and 247 nm for eplerenone. A 3-factor 17-run regular 3-level factorial design was applied to factor screening studies, and Box-Behnken design was utilized for optimization of the experimental parameters of HPTLC for obtaining anticipated chromatographic conditions. Risk assessment was executed to understand the basic method parameters. From the risk assessment, 3 independent parameters, such as band length, saturation time, and wavelength, were selected and studied for the impact of these 3 parameters on the responses. The method yields compact and well-resolved band at RF = 0.24 ± 0.02 for torsemide and RF = 0.50 ± 0.02 for eplerenone. In the linear regression analysis carried out for torsemide and eplerenone, the regression coefficient was found to be r2 = 0.999 for torsemide and r2 =0.995 for eplerenone. The method was validated for validation parameters like accuracy, precision, robustness, limit of detection, and limit of quantification as per the International Conference on Harmonization (ICH) guidelines.