DEVELOPMENT AND VALIDATION OF STABILITY-INDICATING RP-HPLC METHOD FOR THE SIMULTANEOUS ESTIMATION OF RELUGOLIX, ESTRADIOL HEMIHYDRATE AND NORETHINDRONE ACETATE IN ITS SYNTHETIC MIXTURE

A simple, precise, accurate, and stability-indicating RP-HPLC method was successfully developed and validated for the simultaneous estimation of Relugolix, Estradiol Hemihydrate, and Norethindrone Acetate in a synthetic mixture. Chromatographic separation was achieved using a YMC Trait C18 column with a gradient mobile phase of buffer and acetonitrile, at a flow rate of 1.0 mL/min and detection at 238 nm. The developed RP-HPLC method showed excellent performance with good chromatographic separation of Relugolix, Estradiol Hemihydrate, and Norethindrone Acetate. Forced degradation studies were performed under various stress conditions such as acidic, alkaline, oxidative, thermal, and photolytic environments to indicated the stability-indicating capability of the method. The developed method effectively separated the drugs from their degradation products, confirming its suitable for stability studies. The method exhibited strong linearity in the ranges of 200–600 μg/mL for Relugolix, 5–15 μg/mL for estradiol hemihydrate, and 2.5–7.5 μg/mL for Norethindrone acetate, with correlation coefficients exceeding 0.999, respectively. The method demonstrated excellent precision with %RSD values below 2%. The LOD values were 22.6 μg/mL, 0.74 μg/mL, and 0.46 μg/mL, while LOQ values were 68.6 μg/mL, 2.26 μg/mL, and 1.40 μg/mL. and good accuracy (98–102% recovery) and the assay results were found to be within acceptable limits. respectively, indicating high reliability of the method. Overall, the method proved to be reliable and robust, making it suitable for routine quality control and analytical applications in pharmaceutical formulations.