Reaction of Irbesartan with Nitrous Acid Produces Irbesartan Oxime Derivatives, rather than N-Nitrosoirbesartan

Analytical Methodologies to Detect N-Nitrosamine Impurities in Active Pharmaceutical Ingredients, Drug Products and Other Matrices

Since 2018, N-nitrosamine impurities have become a widespread concern in the global regulatory landscape of pharmaceutical products. This concern arises due to their potential for contamination, toxicity, carcinogenicity, and mutagenicity and their presence in many active pharmaceutical ingredients, drug products, and other matrices. N-Nitrosamine impurities in humans can lead to severe chemical toxicity effects. These include carcinogenic effects, metabolic disruptions, reproductive harm, liver diseases, obesity, DNA damage, cell death, chromosomal alterations, birth defects, and pregnancy loss. They are particularly known to cause cancer (tumors) in various organs and tissues such as the liver, lungs, nasal cavity, esophagus, pancreas, stomach, urinary bladder, colon, kidneys, and central nervous system. Additionally, N-nitrosamine impurities may contribute to the development of Alzheimer's and Parkinson's diseases and type-2 diabetes. Therefore, it is very important to control or avoid them by enhancing effective analytical methodologies using cutting-edge analytical techniques such as LC-MS, GC-MS, CE-MS, SFC, etc. Moreover, these analytical methods need to be sensitive and selective with suitable precision and accuracy, so that the actual amounts of N-nitrosamine impurities can be detected and quantified appropriately in drugs. Regulatory agencies such as the US FDA, EMA, ICH, WHO, etc. need to focus more on the hazards of N-nitrosamine impurities by providing guidance and regular updates to drug manufacturers and applicants. Similarly, drug manufacturers should be more vigilant to avoid nitrosating agents and secondary amines during the manufacturing processes. Numerous review articles have been published recently by various researchers, focusing on N-nitrosamine impurities found in previously notified products, including sartans, metformin, and ranitidine. These impurities have also been detected in a wide range of other products. Consequently, this review aims to concentrate on products recently reported to contain N-nitrosamine impurities. These products include rifampicin, champix, famotidine, nizatidine, atorvastatin, bumetanide, itraconazole, diovan, enalapril, propranolol, lisinopril, duloxetine, rivaroxaban, pioglitazones, glifizones, cilostazol, and sunitinib.

Current status and prospects of development of analytical methods for determining nitrosamine and N-nitroso impurities in pharmaceuticals

Nitrosamine impurities in pharmaceuticals have recently been concerned for several national regulatory agencies to avoid carcinogenic and mutagenic effects in patients. The demand for highly sensitive and specific analytical methods with LOQs in the ppb and sub-ppb ranges is among the most significant challenges facing analytical scientists. In addition, artifactual nitrosamine formation during sample preparation and injection leading to overestimation of nitrosamines has received considerable attention. Numerous analytical methodologies have been reported for quantifying nitrosamine impurities in active pharmaceutical ingredients and medicinal products at the interim limit criteria as preventive measures. In this review, we meticulously discuss those reported gas and liquid chromatographic methods for nitrosamine determination in pharmaceuticals in aspects of chromatographic conditions and sensitivity of detection. We also introduce the potential of novel fluorescence-based methods recently developed to rapidly screen nitrosamine impurities. In addition, the review assesses the nitrosation assay procedure (NAP test), which is expected to be a future preventive measure for screening potential nitrosation and identifying suspected contamination with N-nitroso or other potential mutagenic impurities during the drug development process.

Forced degradation studies of elagolix sodium with the implementation of high resolution LC-UV-PDA-MSn (n = 1,2,3…) and NMR structural elucidation

Elagolix sodium (ELS) is a marketed product using to release moderate to severe endometriosis-associated pain. It contains functional groups such as carboxyl group, secondary amino group, 2,4-dioxo pyrimidinyl and several benzyl or benzyl-like position hydrogen atom that are susceptive to occur stress degradation. Forced degradation studies of ELS reveal different degradation profiles of the drug substance which are conducted under photo, thermal, acidic, neutral, alkaline and hydrogen peroxide oxidative conditions in the direction of the ICH guidances. With structural elucidation of LC-PDA/UV-MSⁿ and NMR, the degradants were identified, and seven new degradants are reported in this study. It is confirmed that most of the degradation behaviors of ELS are related to the carboxyl group and secondary amino group in the 3-carboxyl propylamine side chain. Under the oxidative condition using hydrogen peroxide as the oxidant, the secondary amine was oxidized to form an N-hydrogen amine degradant and two further degradants of amine and carbonyl analogs were generated. Under the alkaline degradation condition, the ELS is proven to be stable and no obvious degradants are produced. On the other hand, under the acidic and neutral degradation condition, the 2,4-dioxo pyrimidinyl core of elagolix sodium is stable but the carboxyl group and secondary amine will occur ring cyclization to form the δ-lactam analogs of elagolix sodium. The plausible mechanisms for the degradation of acidic, thermal, photo-degradative and hydrogen peroxide mediated oxidative of elagolix sodium are proposed. It is worth to note that DP-3-4 are the potential degradants which are only found in the solution degradation and are not the real impurities of elagolix sodium.

Current Threat of Nitrosamines in Pharmaceuticals and Scientific Strategies for Risk Mitigation

The current global situation of nitrosamine contamination has expanded from angiotensin-II receptor blockers (ARBs) to wide range of medicines as the risk of contamination via the drug substances, formulation, manufacturing process, and packaging is possible for many drug products. The understanding of chemistry, toxicology, and root causes of nitrosamines are mandatory to effectively evaluate and mitigate the risks associated with the contaminated mutagen. Lessons learnt and scientific findings from previously identified root causes are good examples on how to perform effective risk assessments and establish control strategies. Addressing the risk of nitrosamine contamination in pharmaceuticals requires significant knowledge and considerable resources to collect the necessary information for risk evaluation. Examples of the resources required include a reliable laboratory facility, reference material, highly specific and sensitive instrumentation able handle trace levels of contamination, data management, and the most limited resource - time. Therefore, the supporting tools to assist with risk assessment e.g., shared databases for drug and excipients in concern, screening models for the determination of nitrosamine formation potential, and an in silico model to help with toxicity estimation, have proven to be beneficial to tackle the risk and concern of nitrosamine contamination in pharmaceuticals.

An update on the current status and prospects of nitrosation pathways and possible root causes of nitrosamine formation in various pharmaceuticals

Over the last two years, global regulatory authorities have raised safety concerns on nitrosamine contamination in several drug classes, including angiotensin II receptor antagonists, histamine-2 receptor antagonists, antimicrobial agents, and antidiabetic drugs. To avoid carcinogenic and mutagenic effects in patients relying on these medications, authorities have established specific guidelines in risk assessment scenarios and proposed control limits for nitrosamine impurities in pharmaceuticals. In this review, nitrosation pathways and possible root causes of nitrosamine formation in pharmaceuticals are discussed. The control limits of nitrosamine impurities in pharmaceuticals proposed by national regulatory authorities are presented. Additionally, a practical and science-based strategy for implementing the well-established control limits is notably reviewed in terms of an alternative approach for drug product N-nitrosamines without published AI information from animal carcinogenicity testing. Finally, a novel risk evaluation strategy for predicting and investigating the possible nitrosation of amine precursors and amine pharmaceuticals as powerful prevention of nitrosamine contamination is addressed.