30 July 2020
2020 Webinar: Do all nitrosamines pose a significant level of genotoxic risk?
In this webinar, Lhasa Limited Senior Scientists Dr. Rachael Tennant and Dr. David Ponting discussed the mutagenic effects of nitrosamines, and the correlation with carcinogenic potential. They also described trends in the structure-activity and structure-potency relationships of nitrosamines that can be determined from available data, and how this can be used to improve in silico prediction models.
In light of the recent discovery of nitrosamine impurities in several marketed pharmaceuticals, there has been increased interest in nitrosamine safety assessment. Nitrosamines as a class are considered highly potent, whereby even an intake below the conservative threshold of toxicological concern (TTC) has potential to be a significant genotoxic and carcinogenic risk. As such, they are included within the ‘cohort of concern’ within ICH M7.1
Whilst there are some exceptionally potent (Ames positive) carcinogens within this class, this does not appear to be a universal property of all nitrosamines.2 Of an Ames data set of 402 nitrosamines, 19% were judged to be non-mutagenic, which may suggest that the cohort of concern is overly sensitive.
 ICH M7 Assessment and control of DNA reactive (mutagenic) impurities in pharmaceuticals to limit potential carcinogenic risk | European Medicines Agency (2015)
 Are All Nitrosamines Concerning? (2020) Lhasa Limited
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