Characterization of degradation products of celiprolol hydrochloride using hyphenated mass and NMR techniques

Stress degradation studies were carried out on celiprolol hydrochloride under the ICH prescribed hydrolysis (acidic, basic and neutral), photolytic, oxidative and thermal conditions. Maximum degradation was observed upon hydrolysis, especially in the basic condition. In oxidative condition, the drug degraded only upon severe exposure to H₂O₂, but it remained stable when challenged with AIBN. It also degraded significantly under photolytic conditions. However, the drug was stable to thermal stress. A total of seven degradation products were formed, whose separation was successfully achieved on an Inertsil ODS-3V C-18 HPLC column employing a gradient mobile phase. A comprehensive mass fragmentation pattern of the drug was initially established through the support of high resolution mass spectrometry (HR-MS), multi-stage tandem mass spectrometry (MSⁿ) and on-line H/D exchange MS data. The same approach was then extended to characterization of the degradation products. Additionally, two degradation products were isolated and subjected to 1D/2D NMR studies for their structural confirmation. One of the degradation products showed instability during isolation, therefore, it was subjected to LC-NMR studies for its structural confirmation.