Addressing Nitrosamine Impurities in Pharmaceuticals and Analytical Challenges
Nitrosamine impurities, even in trace amounts, are highly toxic and mutagenic, posing significant cancer risks. Regulatory authorities have identified these impurities in various pharmaceuticals, leading to recalls of drugs like sartans and ranitidine medicines. Recently, attention has shifted to nitrosamine drug substance-related impurities (NDSRIs), which share structural similarities with active pharmaceutical ingredients (APIs). Nitrosamines are classified as Class 1 mutagenic impurities by the ICH M7 guidelines and are categorized by the IARC into Groups 2A and 2B carcinogens.
To address this issue, the United States Pharmacopeia (USP) revised its guidance for the industry, “Control of Nitrosamine Impurities in Human Drugs[GM1] ,” in September 2024. Similarly, in July 2024, the EMA updated “Questions and answers for marketing authorization holders/applicants on the CHMP Opinion for the Article 5(3) of Regulation (EC) No 726/2004 referral on nitrosamine impurities in human medicinal products,[GM2] ” introducing new scientific methods for categorizing N-nitrosamines and setting Acceptable Intakes (AIs).
Conditions fostering nitrosamine formation include the presence of secondary and tertiary amines reacting with nitrous acid. Contamination can occur from vendor-sourced raw materials, manufacturing processes, and storage conditions.
Risk factors include the use of nitrite salts, contaminated materials, and inadequate process control. Nitrosamines may also form in the gastrointestinal tract if vulnerable amines and nitrites are consumed. Manufacturers must consider these factors to mitigate nitrosamine impurities in pharmaceuticals.
Additional challenges include interference from trace nitrosamines in testing materials, contamination during sample preparation, and in situ formation of nitrosamines. Accurate mass techniques may be needed to overcome interference and false positives, with recovery issues due to matrix effects potentially leading to artificially low quantitation results. Sensitivity remains a challenge, especially at ppm levels.
Challenges for LC-MS/MS in Analyzing Nitrosamines
Several complex issues impact LC-MS/MS analysis of nitrosamines:
Sample matrix issues: Reactive components and low analyte response affect peak shape and separation.
Highly polar impurities: These lead to low retention and poor reproducibility, compounded by solubility challenges and complex matrices.
Sensitivity and detection limits: High eluent pH and poor chromatographic retention limit sensitivity, complicating nitrosamine analysis and detection.