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N-Nitrosamine risk assessment and control have become an integral part of pharmaceutical drug product development and quality evaluation. Initial reports of nitrosamine contamination were linked with the drug substance and its manufacturing process. Subsequently, the drug product and aspects of the formulation process have shown to be relevant. Regarding specific formulation contributions to nitrosamine content in a product, one risk lies in possible interactions between nitrosating agents, derived from nitrite in excipients, and vulnerable amines, either present as moieties of the active molecule or as impurities / degradants. However, the limited validated information on nitrite levels in excipients available until now, has been an obstacle for scientists to assess the risk of nitrosamine formation in pharmaceutical products. This has driven the creation of a database to store and share such validated information. The database, maintained by Lhasa Limited, constitutes a central platform to hold the data donated by the pharmaceutical company members on the nitrite concentrations in common excipients measured with validated analytical procedures. The goal of this data sharing initiative is to provide a common framework to contextualize and estimate the risk posed by presence of nitrites to contribute to the formation of nitrosamines in drug products. The major findings from the database analyses are: (1) average nitrite content and batch to batch variance differ among excipients, (2) for solid dosage forms, the nitrite contribution is dominated by the highest formula % excipients, e.g., the fillers (diluents), which are typically used in larger proportion, and are characterized by low nitrite levels and low variability, leading to an average value of 1 µg/g nitrite in a typical formulation, (3) substantial differences in average nitrite content in batches from different excipient vendors potentially reflecting differences in source materials or processing methods for excipient manufacturing. That final point suggests that future selection of raw materials or processing by excipient manufacturers may help reduce nitrite levels in finished drug product formulations, and thus the overall risk of nitrosamine formation in cases where the product contains vulnerable amines.

Our letter to the editor of Heliyon outlines queries on the methodology and sample preparation used in article e06179, published in 2021. The nitrite measurements reported are higher than those observed in our experience. In the interest of reporting nitrite levels that are fully accurate, we would like to discuss the findings with the article authors.