Abstract：
Mass balance in drug substances release testing is a critical quality attribute in pharmaceutical manufacturing that continues to challenge modern analytical characterization. This specific perspective of mass balance is lacking in literature, and the following work addresses the knowledge gap related to this topic by examining an in-depth case study and detailing the systematic investigation into mass imbalance observed during release testing of a small molecule API. The process followed a logical stepwise progression beginning with most probable causes and expanded to more obscure causes that require a deeper examination of the API in question until the undetected impurity in question was finally identified. The discovered impurity was eventually found to be formed from a unique side reaction that led to the formation of API-related oligomer impurities, which had eluded conventional small molecule release testing strategies. Ultimately, the characterization gap was traced back to deficiency in the LC results of the developed API purity methods. More importantly, this gap provides an ideal opportunity to highlight common oversights and pitfalls encountered in early phase pharmaceutical development especially as it relates to the method development of truly representative chromatography methods in the API characterization. The work reflects on the key lessons learned from the highlighted pitfalls that were encountered in this case study and offers strategic insights to guide and to improve the development workflow for drug substance characterization strategies.
摘要：
药物释放测试中的质量平衡是制药制造中的关键质量属性，继续挑战现代分析表征。这种物质平衡的具体视角在文献中是缺乏的，以下工作通过研究深入的案例研究并详细介绍了在小分子API释放测试过程中观察到的质量不平衡的系统研究，解决了与该主题相关的知识差距。该过程遵循逻辑逐步进展，从最可能的原因开始，并扩展到更模糊的原因，需要对所讨论的API进行更深入的检查，直到最终确定未检测到的杂质。最终发现发现的杂质是由独特的副反应形成的，导致形成与API相关的低聚物杂质，这与传统的小分子释放测试策略相距甚远。最终,表征差距可以追溯到开发的API纯度方法的LC结果中的缺陷。更重要的是,这一差距为突出早期药物开发中遇到的常见疏忽和陷阱提供了理想的机会,尤其是与API表征中真正具有代表性的色谱方法的方法开发有关.这项工作反映了从本案例研究中遇到的突出陷阱中吸取的关键经验教训，并提供了战略见解，以指导和改进药物表征策略的开发工作流程。
