Comprehensive study on the forced degradation impurities of vericiguat with high-resolution LC-MS/MS and 1D/2D-NMR

Vericiguat (VER), a novel soluble guanylate cyclase agonist for heart failure, was subjected to comprehensive forced degradation studies to assess its stability and elucidate degradation pathways. The study was conducted in accordance with ICH guidelines, including alkaline, acidic, oxidative, photolytic, and thermal stress conditions. And tentatively structural identification of degradation impurities was carried out using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). The results indicated that VER was susceptible to degradation under alkaline (NaOH) and hydrogen peroxide (H₂O₂) oxidative conditions, yielding nine degradation impurities (DIs 1-7, 9, 10). Among these, eight have not been previously reported, with the exception of DI-7. Moreover, under a newly introduced free-radical oxidation condition using benzoyl peroxide (BPO), two additional novel impurities (DI-8 and DI-11) were generated. And two major degradants (DI-3-2 and DI-5) were isolated and their structures were confirmed by 1 Dimension/2 Dimension-Nuclear Magnetic Resonance (1D/2D-NMR) analysis. Based on the structures of the degradation impurities, the degradation pathways were elucidated and the molecular stability was investigated. The results demonstrate that the primary degradation mechanisms involved pyrimidine ring cleavage, oxidation of the amino group, hydrolysis of ester and amide bonds, as well as intramolecular cyclization and rearrangement. This study successfully established a comprehensive impurity profile for VER and provided robust scientific data for formulating its quality standards, thereby supporting stability assessment and quality control during pharmaceutical development.