Analytical Quality by Design-Guided Development and Validation of Stability-Indicating RP-HPLC Method for the Simultaneous Quantification of Saquinavir and Tipranavir in Pharmaceutical Formulations

Objective: To develop and validate a robust and stability-indicating RP-HPLC method for the simultaneous estimation of Saquinavir and Tipranavir in pharmaceutical formulations using an Analytical Quality by Design (AQbD) approach. Methods: Chromatographic conditions were optimized using a Box–Behnken design by evaluating mobile phase composition, buffer pH and flow rate as critical method parameters. The optimized method employed a Inertsil C18 column (250 mm × 4.6 mm, 5 µm particle size) with methanol and phosphate buffer (65:35, v/v; pH 3.5) at a flow rate of 1.0 ml/min and detection at 248 nm. The method was validated according to ICH Q2(R1) guidelines for specificity, linearity, accuracy, precision, sensitivity, robustness, and stability-indicating capability. Forced-degradation studies were performed under different stress conditions. ² values of 0.9992 for Saquinavir and 0.9995 for Tipranavir. Accuracy was satisfactory, with recoveries of 98–102%, while precision showed %RSD values below 2%. The method exhibited good sensitivity with low detection and quantification limits. Forced-degradation studies demonstrated effective separation of degradation products from the drug peaks, confirming the stability-indicating capability. The method remained Results: The method showed excellent linearity with r reliable under deliberate variations in chromatographic conditions. Conclusion: The developed AQbD-based RP-HPLC method was successfully validated and demonstrated satisfactory specificity, linearity, accuracy, precision, sensitivity, robustness, and stability-indicating capability. The method is suitable for routine quality control and stability assessment of Saquinavir and Tipranavir in pharmaceutical formulations.