RESUMEN
Two unknown solution degradants were found during the dissolution testing in 0.1-M HCl for olmesartan medoxomil (OLM) tablets. The structure of the degradants was identified and characterized by liquid chromatography-ultraviolet (LC-UV), liquid chromatography with tandem mass spectrometry (LC-MS/MS), and nuclear magnetic resonance (NMR) and demonstrated to be cyclization of tetrazole and benzene in the olmesartan (OL) and OLM structures. A series of studies including stress studies, simulation studies, and mechanism-based studies were performed to reveal the potential mechanisms that lead to the formation of the unknown degradants. The study results demonstrated that the degradation was catalyzed with radicals that originated from the metal ions leached from the inner surface of high-performance liquid chromatography (HPLC) glass vials with dissolved oxygen under acidic condition. Prerinsing the glass vials with acidic solution dissolved with EDTA can effectively avoid the generation of such oxidative impurities. The present work provides new insights into the understanding of degradation pathways of OLM, which might support the development of OLM tablets.
Asunto(s)
Espectrometría de Masas en Tándem , Cromatografía Líquida de Alta Presión/métodos , Cromatografía Liquida/métodos , Iones , Olmesartán Medoxomilo , Espectrometría de Masas en Tándem/métodosRESUMEN
Analytical solutions of clofazimine drug substance stored in glass HPLC vials were found to undergo degradation at room temperature occasionally. At the time of each sample preparation, it was unpredictable if a particular solution would undergo such solution degradation. Once the degradation peak was observed in a particular vial, typically within 24h, it would keep growing until reaching a total yield of approximately 2%. By using a strategy that combines LC-PDA/UV-MSn with mechanism-based stress studies, followed by preparative HPLC separation and subsequent structure characterization by 1D and 2D NMR, the unknown peak was identified as a clofazimine nitrite ester. It apparently results from nucleophilic substitution of clofazimine by residual nitrite leaching out of the inner surface of the glass HPLC vials used in the sample preparation. Overall, the percentage of the sample solutions that underwent solution degradation is approximately â¼10% to 15%, when the sample solutions were stored in glass HPLC vials at room temperature. Over the period of the analytical method development, it was found that the occurrence of the degradation can be suppressed when the solutions were stored under refrigerated condition (2 - 8°C) or when the samples were prepared in less acidic diluents.
Asunto(s)
Cromatografía Líquida de Alta Presión/instrumentación , Clofazimina/análisis , Contaminación de Medicamentos , Vidrio/química , Nitritos/química , Artefactos , Frío , Estabilidad de Medicamentos , Diseño de Equipo , Concentración de Iones de Hidrógeno , Espectrometría de Masas , Reproducibilidad de los Resultados , Espectrofotometría Ultravioleta , Factores de TiempoRESUMEN
Unpredictable degradation of Ezetimibe solutions in pure acetonitrile occurs when they are stored in glass HPLC vials. The occurrence of the two main degradation peaks and one minor peak was unpredictable at the time of each sample preparation and over time, it appeared that approximately 15% of the sample solutions in glass HPLC vials would eventually show the degradation peaks. Once the degradation peaks occurred in a particular vial, typically within 24h, they would keep growing until reaching a total yield of about 4-5%. Through a comprehensive investigation, it is determined that the solution degradation is caused by a base-catalyzed process, during which ezetimibe undergoes (1) dimerization to form two dimeric impurities, which have not been reported in the literature, and (2) to a less degree, isomerization to produce an isomeric impurity that has been reported before.