Stability Indicating RP-UPLC Method for Impurity Profiling of Darunavir and Ritonavir in Fixed Dose Drug Combination Product

Background: The goal of the proposed study was to develop and validate stability indicating mass compatible reverse phase UPLC method for impurity profiling of Darunavir Ethanolate and Ritonavir degradation impurities in fixed -dose drug combination products. Materials and Methods: The optimized chromatographic condition includes use of Zorbax Bonus C 18 column (150x2.1 mm, 1.8 mu m) with mobile phase A (Buffer (55): Methanol (45)) and mobile phase B (Acetonitrile: (30) and Methanol (70)), flow rate of 0.22 mL/min and detection at 240 nm with gradient program of 50 min. The method was validated as per ICH quality guideline Q2 (R1) including specificity by forced degradation study to confirm suitability for intended use. Results: The observed retention time for Darunavir was 11.4 min and for Ritonavir was 30.0 min. The Limit of Quantitation (LOQ) for all degradation impurities found is 0.05%, equivalent to the reporting threshold level. The method was found linear and accurate in the range of LOQ to 150% with an observed range of % accuracy of 90.1 to 106.3 for all known impurities. The method was found precise based on less than 10.0% RSD and robust for deliberate changes. Considering the use of a volatile mobile phase, the method can be applied for LC -MS -based analysis for mass identification. Conclusion: The developed UPLC method was applied for impurity profiling during the release and stability study of Darunavir Ethanolate and Ritonavir in fixed -dose drug combination products.