Response Surface Methodology-Assisted Development and Validation of a Stability-Indicating HPLC-PDA Method for...

Reliable and stability-indicating analytical methods are required to support the development and quality control of Medroxyprogesterone Acetate (MPA), particularly in emerging solid-state pharmaceutical systems such as microcrystals. In this analytical method development and validation study, a stability-indicating reversed-phase high-performance liquid chromatography method with photodiode array detection (HPLC-PDA) was developed and validated using Response Surface Methodology (RSM) based on a Box-Behnken design for the quantitative determination of MPA in microcrystalline systems. RSM was applied to systematically evaluate the effects and interactions of critical chromatographic parameters, including methanol proportion, acid modifier concentration, and flow rate, enabling simultaneous optimisation of chromatographic responses related to sensitivity, retention behaviour, and peak symmetry. The optimised method demonstrated balanced chromatographic performance and was validated in accordance with the International Council for Harmonisation guideline Q2(R1). The method exhibited excellent linearity over the concentration range of 0.5-100 µg/mL (r = 0.9999), with accuracy ranging from 99.35% to 100.36% and precision expressed as relative standard deviation (%RSD) below 1.56%. The method also demonstrated adequate sensitivity, with limit of detection (LOD) and limit of quantification (LOQ) values of 0.045 µg/mL and 0.137 µg/mL, respectively, confirming its suitability for quantitative analysis. Forced degradation studies demonstrated that MPA was particularly susceptible to alkaline-thermal stress, resulting in the formation of distinguishable degradation-related peaks adjacent to the parent compound peak, supporting the stability-indicating capability of the method. Overall, the developed RSM-assisted HPLC-PDA method is suitable for routine analysis, stability studies, and formulation-oriented pharmaceutical quality control of MPA microcrystals.