Topical issue in the pharmaceutical industry today is still very much related to nitrosamines. Recently, there has been a recall of certain medicines that were found to contain nitrosamines in excess of permitted limits, which led the regulatory authorities to require a risk assessment for nitrosamine impurities to accompany the marketing authorisation application. Nitrosamines are classified by the IARC as potentially carcinogenic to humans and by the FDA as a highly potent mutagenic carcinogen, requiring strict control of levels. Most nitrosamines with a nitroso functional group (N=O) are formed by reaction between secondary amines and nitrites in acid. Nitrites are strong nitrosating agents and can be found in medicines in excipients, which are the key components in the pharmaceutical form. The excipients may also contain reactive trace impurities that can react with the active substance, leading to reduced or even lost efficiency of the medicinal product and the formation of potentially hazardous degradation products. The problem with nitrite as an impurity arises when it interacts with nitrogen-containing pharmaceutical compounds, as this can lead to the formation of N-nitroso compounds (nitrosamines). To try to prevent nitrosamines from forming in advance, we can test excipients for nitrite content and assess the risk of nitrosamines from an early stage of product development. The use of low-nitrite excipients could also reduce exposure to the risk of nitrosamine formation.
In the framework of the MSc thesis, we developed, optimised and validated the HPLC method for the determination of trace nitrites in excipients. We have developed an HPLC method for the determination using derivatization with a reagent that allows detection with a fluorescence detector. The method developed is accurate, precise and reproducible. As part of the Master`s thesis, we analysed the excipients, evaluating them for low- and high-risk for the formation of nitrosamines, based on the nitrite content determination. We also analysed the active substance, intermediates and the final product of the model pharmaceutical manufacturing process to the nitrite levels and, consequently, to the increased risk of nitrosamines through the determination of nitrite content.
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