The clinical and regulatory status of NDSRI: A global imperative

Detecting N-nitrosamine impurities in medicines has been a significant challenge for drug manufacturers and regulators, especially with the recent emergence of nitrosamine drug substance-related impurities (NDSRIs). The formation of NDSRIs is complex and primarily associated with reactions in the drug product. This paper explores the current technical knowledge on forming these impurities, including the risk factors, reaction conditions, and possible mitigation strategies. While significant scientific progress has been made in these areas, substantial gaps in mechanistic knowledge still make accurate predictions of NDSRI formation very difficult. The pharmaceutical industry's continued work on potential mitigation strategies and the generation of additional scientific data to address these knowledge gaps are crucial. Regulatory guidance and policy will continue to evolve in response to further changes in scientific understanding. In this article, we will delve into the detection methods, the mechanism of action, sample preparation techniques, and regulatory limits for nitrosamine impurities. We also discuss various reported nitrosamine impurities, their chemical structures, and their detection using methods like LC-MS/MS, GC-MS-HS, and HPLC. Additionally, we discuss different sample preparation techniques, such as solid-phase extraction, liquid-liquid extraction, and rapid-fire techniques. This review is intended to provide detailed information to analytical personnel working in various quality control laboratories and research organizations.