EMA Q&A Appendix 1 Update: EMA/393815/2024/Rev. 6. 1 September 2024. A word on Non-Mutagenic N-Nitrosamines.

With the last modification of the Acceptable Intake (AI) value for N-nitroso-ciprofloxacin in the EMA Q&A Appendix 1 on "Acceptable Intakes established for N-nitrosamines" (effective 01/09/2024), we now see up to 10 N-nitrosamines classified as NonMutagenic Impurities (NMI). This classification is based on negative in-vivo mutagenicity studies (whether compound-specific testing or testing on a surrogate).

According to the EMA Q&A, a negative result from a relevant, well-conducted in vivo mutagenicity study allows the N-nitrosamine to be controlled as an NMI under ICH Q3A(R2) and ICH Q3B(R2) limits, irrespective of the limit calculated through other methodologies.

Key insights from these 10 NMI N-nitrosamines:
• All are classified as Nitrosamine Drug Substance-Related Impurities (NDSRIs).
• 5 out of 10 contain one or two carboxylic acid groups, which act as potency deactivating features.
• 3 out of 10 are N-nitrosamines derived from macrolide antibiotics.

This update highlights the evolving landscape of nitrosamine regulation and the increasing reliance on robust scientific studies to refine impurity control.