Modified NAP test: A simple and Responsive Nitrosating Methodology for Risk Evaluation of NDSRIs

N-Nitroso compounds have been listed as one of the cohorts of concern as per ICH M7. In recent years, the regulatory focus has shifted from common nitrosamines to nitroso-impurities of drug products. Thus, the detection and quantification of unacceptable levels of nitrosamine drug substance-related impurities are of great concern for analytical scientists during drug development. Moreover, risk assessment of nitrosamines is also an essential part of the regulatory filling. For risk assessment, the Nitrosation Assay Procedure suggested by WHO expert group in 1978 is being followed. However, it could not be adopted by the pharmaceutical industries due to the limitation of drug solubility and artefact formation in the test conditions. In this work, we have optimized an alternative nitrosation test to investigate the likelihood of direct nitrosation. The technique is simple, where the drug solubilized in an organic solvent is incubated at 37°C with a nitrosating agent named tertiary butyl nitrite in a 1:10 molar ratio. LC-UV/MS-based chromatographic method was developed to separate drug substances and respective nitrosamine impurities using the C18 analytical column. The methodology was successfully tested on five drugs with varying structural chemistry. The procedure is straightforward, effective, and quick for the nitrosation of secondary amines. This modified nitrosation test and WHO prescribed nitrosation test have been compared and found that the modified methodology is more effective and time-saving.