Quantitation of Reactive Nitrosating Agents in Pharmaceutical Excipients for N-Nitrosamine Risk Assessments

Given that pharmaceutical excipients contain traces of nitrosating agents (NOx; e.g., nitrites) that are capable of reacting with amines to afford N-nitrosamines, N-nitrosamine risk assessment is an essential part of drug product development. However, the quantitation and control of all NOx during drug product manufacturing is challenging. Herein, we established a simple method for selectively quantifying the NOx that contributes to N-nitrosamine formation (termed reactive NOx) in excipients. According to our procedure, first a certain amine (e.g., dimethylamine) is added to the excipient. Then, the mixture is tightly sealed and stored at an elevated temperature to induce nitrosation, and the formed N-nitrosamine (e.g., N-nitrosodimethylamine) is quantified by liquid chromatography–tandem mass spectrometry. The developed method enables the highly accurate estimation of the maximum potential amount of N-nitrosamine that can be formed during manufacturing and storage, thus enabling realistic N-nitrosamine risk assessment and facilitating drug product development (e.g., formulation design).