Development and Validation of Stability Indicating RP-HPLC Method for the Simultaneous Estimation of Dapagliflozin and Eplerenone in Bulk and Synthetic Mixture

A stability-indicating analytical method utilizing reverse-phase high-performance liquid chromatography was developed and validated for the simultaneous quantification of dapagliflozin and eplerenone in bulk drug materials and a laboratory-prepared synthetic mixture. Chromatographic separation was achieved on a Shim-pack C18 column (250 × 4.6 mm, 5 µm) using an isocratic elution of methanol and water (80:20, v/v) at a constant flow rate of 1.0 mL/min. Detection was carried out with a photodiode array detector set at 265 nm. The method exhibited a linear response across concentration ranges of 1–5 µg/mL for dapagliflozin and 2.5–12.5 µg/mL for eplerenone, with correlation coefficients exceeding 0.999. Validation studies, conducted in accordance with the International Council for Harmonization (ICH) Q2(R2) guidelines, confirmed that the method was precise, accurate, robust, specific, and sensitive. The stability-indicating capability was verified through forced degradation experiments under acidic, alkaline, oxidative, thermal, and photolytic stress conditions, where degradation products were adequately resolved from the parent compounds using the developed method. The validated method was successfully applied to the analysis of a synthetic mixture, yielding assay results of 99.56% for dapagliflozin and 99.48% for eplerenone. Therefore, the proposed method is suitable for routine quality control analysis and stability studies.