QUALITY BY DESIGN (QBD) – BASED RP – HPLC METHOD DEVELOPMENT AND VALIDATION FOR THE SIMULTANEOUS DETERMINATION OF DARUNAVIR AND RITONAVIR

Abstract

The Quality by Design (QbD) approach was employed to achieve method optimization by systematically evaluating the influence of critical method parameters (CMPs) such as mobile phase composition, flow rate, and detection wavelength using Design of Experiments (DoE). The optimized chromatographic conditions ensured sharp, well-resolved peaks with minimal tailing and reduced run time, confirming method efficiency and economy. The method was developed by using a Sunfire C18 column with a flow rate of 1ml/min the mobile phase was selected was Methanol: Ammonium Acetate (40:60 v/v) and the results had exhibited excellent linearity over the concentration range of 5–30 μg/ml for Ritonavir and 30–180 μg/ml for Darunavir, with correlation coefficients (R² = 0.999) for both analytes. The regression equations were y = 6626.1x + 340.57 for Ritonavir and y = 9239.1x + 991.54 for Darunavir. The mean assay results demonstrated high accuracy—99.95% for Ritonavir and 100.24% for Darunavir. The method was found to be specific, showing no interference from excipients or other components. System suitability and precision results yielded %RSD values within acceptable limits (≤2%), confirming repeatability and reproducibility. Accuracy studies showed recoveries of 99.75% (Ritonavir) and 99.87% (Darunavir), while LOD and LOQ were 0.02 μg/ml and 0.05 μg/ml for Ritonavir, and 0.59 μg/ml and 1.78 μg/ml for Darunavir, respectively, indicating the high sensitivity of the method. Robustness testing under minor deliberate variations further confirmed the reliability of the method within the defined design space. The proposed QbD-optimized RP-HPLC method is simple, accurate, robust, and economical, and can be effectively adopted for routine quality control analysis of Ritonavir and Darunavir in pharmaceutical formulations