Stability Indicating High Performance Liquid Chromatography Method Development, Validation, and Characterization of Forced Degradant Product by Liquid Chromatography–Mass Spectroscopy for Molnupiravir and Favipiravir.

This article focuses on the development and validation of a stability-indicating reverse phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination and characterization of degradation products of Molnupiravir (MLP) and Favipiravir (FAV), two antiviral drugs used in COVID-19 treatment. The study subjected both drugs to forced degradation under acidic, basic, oxidative, thermal, and photolytic conditions, finding Favipiravir more susceptible to degradation, especially under acidic and basic stress, while both drugs remained stable under thermal and photolytic conditions. The validated RP-HPLC method demonstrated high specificity, accuracy, precision, linearity (5–500 μg/mL), and robustness according to International Council for Harmonisation (ICH) Q2(R1) guidelines, enabling effective quantification of MLP and Favipiravir in the presence of impurities. The research supports the method's application in quality control and further confirmatory studies involving these antiviral agents.