ABSTRACT:
Vonoprazan, is a potassium-competitive acid blocker used in the form of fumarate for the treatment of gastroduodenal ulcers and reflux esophagitis and can be combined with antibiotics for the eradication of Helicobacter pylori. Despite its clinical significance, limited stability-indicating analytical methods have been reported for its determination. This study addresses this gap by establishing a robust isocratic HPLC method, developed and validated under ICH Q1A(R2) and ICH Q1B guidelines, for the accurate and sensitive determination of vonoprazan, with characterization of its degradation products via LC-MS. In accordance with the guidelines, forced degradation was conducted under acidic, basic, oxidative, photolytic, and thermal stress conditions to ensure the separation of vonoprazan from its degradation products. Chromatographic separation was achieved using a FINEPAK SIL C-18 column and an acetonitrile:0.1% formic acid mobile phase (70:30, v/v), with detection at 266 nm. The method demonstrated excellent linearity (2–12 µg/mL, R² = 0.9981), precision (%RSD < 2), and accuracy (99.909–100.263%), with LOD and LOQ values of 0.086 and 0.261 µg/mL, respectively. Vonoprazan degraded under acidic, alkaline, and oxidative conditions, while it was stable under photolytic and thermal stress conditions. LC-MS identified two major degradation products, and their structures and proposed pathways were elucidated. The proposed HPLC method provides simple, accurate and reproducible quantitative analysis for the determination of vonoprazan in the presence of its degradants and suggests the need to protect vonoprazan from hydrolysis and oxidation during formulation and storage.