Development of a Stability‐Indicating HPLC Method for Quantification of Belzutifan and Its Related Impurities With LC–MS/MS Characterization of Degradation Products

A stability-indicating HPLC method was developed to quantify belzutifan and its related and degradation impurities, and LC-MS/MS technology was used for the characterization of stress-induced degradation products (DPs). Adequate separation was attained on an waters X Bridge C18 column with dimensions 150 × 4.6 mm (3.5 μm) at 30°C, utilizing acetonitrile and 0.1% formic acid in water (60:40) v/v as the mobile phase. This method was set at a flow rate of 0.8 mL/min, and a PDA detector was used for detection. The method demonstrated excellent specificity, accuracy (98.24%-101.01% recovery), precision (%RSD < 2), linearity (R² > 0.999), and sensitivity, with resolution > 2.0. Forced degradation studies showed no degradation under UV and thermal stress but significant degradation under acidic, basic, and oxidative conditions, yielding two acid-induced (DP A/B-1 and A-2), one base-induced (DP A/B-1), and one peroxide-induced (DP O-1) DPs. The degradation pathways of DPS were established by using the mass fragmentation patterns. This method represents stability, is compliant with ICH guidelines, and is well suited for routine quality control and comprehensive stability assessment of belzutifan. A representation of the stress study of belzutifan is shown.