QUALITY BY DESIGN-ASSISTED DEVELOPMENT AND VALIDATION OF A ROBUST RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF PRAMIPEXOLE AND RASAGILINE IN A SYNTHETIC MIXTURE

Abstract

Background: Simultaneous estimation of low-dose, extended-release combinations in pharmaceutical preparations requires highly robust, sensitive, and validated analytical methods. This study presents a systematic Quality by Design (QbD)-assisted reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous estimation of Pramipexole (PRA) and Rasagiline (RAS) in a synthetic mixture. Methods: A three-level factorial design utilizing Design-Expert software was employed to evaluate the impact of critical chromatographic factors-specifically the proportion of acetonitrile, flow rate, and column temperature on analytical target profile responses including retention times, tailing factors, and resolution. Chromatographic separation was achieved on a Zorbax SB C18 column (250 × 4.6 mm, 5 ????m) using a mobile phase consisting of acetonitrile and 0.1% ortho-phosphoric acid in water at an optimized flow rate of 0.5 mL/min and a detection wavelength of 210 nm. Results: Under optimized conditions, sharp, well-resolved peaks were obtained with retention times of 5.48 min for Pramipexole and 11.15 min for Rasagiline, and a resolution of 15.52. The method was validated in accordance with International Council for Harmonisation (ICH) guidelines, showing excellent linearity (????2 > 0.999), high accuracy (mean recovery between 99.51% and 99.83%), and precision (RSD < 2%). Furthermore, forced degradation studies under acid, base, oxidative, and thermal stress conditions demonstrated the stability-indicating power of the method, effectively resolving intact drugs from degradation products. Conclusion: The developed QbD-assisted RP-HPLC method is reliable, accurate, and suitable for routine quality control and stability testing of Pramipexole and Rasagiline pharmaceutical formulations