I share the good example of nitrite calculation contained in excipients and others demonstrated by Dr. Urquhart in nitrosamine workshop last week.
According to him, contamination risk is evaluated with 100% conversion at first. Next a conversion factor, whose detail is not included here, is considered and the calculated value is compared with (adjusted) ADI. This example may concern with API with secondary or tertiary amine, however if the amount of these amines is at impurity levels, the contamination risk of nitrosamines is not crucial in general, as illustrated in the paper, Potential for the Formation of N-Nitrosamines during the Manufacture of Active Pharmaceutical Ingredients: An Assessment of the Risk Posed by Trace Nitrite in Water.
Anyway the amount of nitrite in excipients and others will be the key of the risk assessment, especially API or excipient has certain amine moiety.
@GENERAPHARM
Thanks a lot. Even in this example, lactose includes trace amounts of nitrite. Lactose of this brand may be better in quality.