Abstract

A selective and robust High Performance Liquid Chromatography (HPLC) method was developed for the separation and quantification of futibatinib, which is a novel irreversible fibroblast growth factor receptors (FGFRs) inhibitor, and its known impurities. The method optimization involves the evaluation of various chromatographic parameters, and results proved that the Kinetex C18 column and an isocratic mobile phase of acetonitrile and aqueous phosphate buffer (pH 4.1, 65:35 v/v) at 0.8 mL/min were optimal for the resolution of futibatinib and its impurities. The forced degradation studies reveal the suscepti- bility of futibatinib towards acidic and oxidative conditions. The degradation follows pseudo-first-order kinetics, with maximum degradation recorded under acidic conditions (k = 0.0413 h -1 , t 1/2 = 16.78 h) and then by oxidative stress (k = 0.0331 h -1 , t 1/2 = 20.93 h). Five major Degradation Products (DPs) were identified in which DP 1 (m/z 319.7691) is a vinyl halide produced through Markovnikov-type electrophilic addition, DP 2 (m/z 391.3912) is a bis-hydroxy derivative produced through oxidative demethylation, DP 3 (m/z 365.968) and DP 4 (m/z 296.2975) are the products of acid-induced hydrolysis and ring cleavage whereas DP 5 (m/z 433.4311) is a nitroso-derivative produced through oxidative modification of the amine group. The in-silico toxicity predictions classify all DPs under toxicity class 4, indicating consistent neurotoxic and carcinogenic potential, whereas DP 4 and 5 show mutagenic and immunotoxin risks. This study offers the first comprehensive degradation profiling of futibati- nib by providing a stable analytical platform for quality control, regulatory compliance, and formulation stability.