Quantitative determination of eplerenone in bulk drug and tablet dosage form by TLC/densitometry

Abstract

A simple, selective and precise thin-layer chromatography /densitometry method has been developed for determination of eplerenone, both as a bulk drug and in tablet formulation. The method was validated as per International Conference on Harmonization (ICH) guidelines. Aluminium foil TLC plates precoated with silica gel 60F₂₅₄ were used as the stationary phase and ethyl acetate: toluene: triethylamine 6:4:0.4 (v/v) as mobile phase. A compact band (R_f 0.45 ± 0.02) was obtained for eplerenone. Densitometric analysis was performed in the absorbance mode at 241 nm. Linear regression analysis revealed a good linear relationship with (r² = 0.9991 ± 0.0004) between peak area and concentration in the range 200 - 1200 ng band ^-1. The mean value ± S.D. of the slope and intercept were 4.84 ± 0.069 and 372.26 ± 7.66, respectively. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 11 and 32 ng, respectively. The % RSD for intra-day and inter-day precision of   eplerenone was found to be 0.65% and 0.97 %, respectively. The mean percentage recovery for eplerenone was found to be in the range of 99 - 101%. Eplerenone was subjected to acid and alkali hydrolysis, oxidation, photochemical and thermal degradation. The drug undergoes degradation under acidic, basic and oxidation conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation and stable for photochemical and thermal conditions.