N-Nitroso N-Desmethyl Azithromycin is a nitrosamine impurity that can potentially occur under conditions related to the formulation and manufacturing process for the drug product

APIs containing secondary amine or dimethyl tertiary amine centers are prone to NDSRI formation via nitrosation. FDA has Recommended AI Limits for Certain Hypothetical NDSRIs based on Predicted Carcinogenic Potency Categorization.