Tolerability of risk: A commentary on the nitrosamine contamination issue

Method development and validation for determination of N-Nitrosamines in pharmaceutical preparations by LC-MS/MS: Application to extractables and leachables studies

The use of highly sensitive and reliable analytical methods is essential for Extractables & Leachables studies. Especially the determination of N-Nitrosamines in drugs, which have carcinogenic properties and may contaminate drugs at trace levels, is quite important. In this study, a new, sensitive, short-time and reliable liquid chromatography with tandem mass spectrometry method was developed for the analysis of 15 N-Nitrosamines defined in the European Pharmacopoeia within the scope of Extractables & Leachables studies and validated according to the International Council for Harmonization (ICH Q2 (R2)). The analysis of N-Nitrosamines was carried out in positive mode using an Atmospheric Pressure Chemical Ionization source in the dynamic multiple reaction monitoring scanning mode. In the chromatographic separation, gradient elution was applied using a reverse phase Phenyl column and the mobile phase (A: 0.1 % formic acid in ultrapure water, B: 0.1 % formic acid in methanol); total analysis time was 16 mins and the flow rate was optimized as 0.6 mL/min. N-Nitroso-dimethylamine-d6 was used as an internal standard. The developed method was used in extractables studies to control the potential presence of N-Nitrosamines that may be caused by interactions between the product and primary packaging materials (e.g. polypropylene bag, LDPE container, disposable eye drop packaging and bromobutyl stopper). It was also successfully applied to pharmaceutical preparations containing sugammadex, metformin, gliclazide and paracetamol in the leachables studies.

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.

Nitrosamines crisis in pharmaceuticals - Insights on toxicological implications, root causes and risk assessment: A systematic review

The presence of N-nitroso compounds, particularly N-nitrosamines, in pharmaceutical products has raised global safety concerns due to their significant genotoxic and mutagenic effects. This systematic review investigates their toxicity in active pharmaceutical ingredients (APIs), drug products, and pharmaceutical excipients, along with novel analytical strategies for detection, root cause analysis, reformulation strategies, and regulatory guidelines for nitrosamines. This review emphasizes the molecular toxicity of N-nitroso compounds, focusing on genotoxic, mutagenic, carcinogenic, and other physiological effects. Additionally, it addresses the ongoing nitrosamine crisis, the development of nitrosamine-free products, and the importance of sensitive detection methods and precise risk evaluation. This comprehensive overview will aid molecular biologists, analytical scientists, formulation scientists in research and development sector, and researchers involved in management of nitrosamine-induced toxicity and promoting safer pharmaceutical products.

Mechanisms of Nitrosamine Mutagenicity and Their Relationship to Rodent Carcinogenic Potency

A thorough literature review was undertaken to understand how the pathways of N-nitrosamine transformation relate to mutagenic potential and carcinogenic potency in rodents. Empirical and computational evidence indicates that a common radical intermediate is created by CYP-mediated hydrogen abstraction at the α-carbon; it is responsible for both activation, leading to the formation of DNA-reactive diazonium species, and deactivation by denitrosation. There are competing sites of CYP metabolism (e.g., β-carbon), and other reactive species can form following initial bioactivation, although these alternative pathways tend to decrease rather than enhance carcinogenic potency. The activation pathway, oxidative dealkylation, is a common reaction in drug metabolism and evidence indicates that the carbonyl byproduct, e.g., formaldehyde, does not contribute to the toxic properties of N-nitrosamines. Nitric oxide (NO), a side product of denitrosation, can similarly be discounted as an enhancer of N-nitrosamine toxicity based on carcinogenicity data for substances that act as NO-donors. However, not all N-nitrosamines are potent rodent carcinogens. In a significant number of cases, there is a potency overlap with non-N-nitrosamine carcinogens that are not in the Cohort of Concern (CoC; high-potency rodent carcinogens comprising aflatoxin-like-, N-nitroso-, and alkyl-azoxy compounds), while other N-nitrosamines are devoid of carcinogenic potential. In this context, mutagenicity is a useful surrogate for carcinogenicity, as proposed in the ICH M7 (R2) (2023) guidance. Thus, in the safety assessment and control of N-nitrosamines in medicines, it is important to understand those complementary attributes of mechanisms of mutagenicity and structure-activity relationships that translate to elevated potency versus those which are associated with a reduction in, or absence of, carcinogenic potency.

Structure Identification and Risk Assurance of Unknown Impurities in Pramipexole Oral Drug Formulation

Impurities compounds in any pharmaceutical product or drug substance are inevitable from a chemistry point of view. The quality and safety of a pharmaceutical product are also significantly affected by these impurities content; therefore, impurities need to be identified and characterized through the use of appropriate analytical methods. Pramipexole is a nonergot dopamine agonist used to treat various Parkinson's disease symptoms. Two unknown impurities were detected from a pramipexole dihydrochloride solid dosage form. These impurities were identified and characterized using ultra-performance liquid chromatography coupled with high-resolution mass spectroscopy (UPLC-HRMS). These impurities were found to be enriched when mannitol existed in the formulation. The structure and mechanism involved in the existence of the impurities were proposed. Furthermore, observation of the binding affinity potential risk of these impurities to the pramipexole receptor has also been demonstrated through molecular docking and molecular dynamics simulation study. The binding energy result showed that pramipexole interaction with dopamine receptors D2 and D3 was higher than pramipexole mannose adduct and pramipexole ribose adduct.

Nitrosamine Impurities in Pharmaceuticals: An Empirical Review of their Detection, Mechanisms, and Regulatory Approaches

Since their discovery in valsartan-containing drugs, nitrosamine impurities have emerged as a significant safety problem in pharmaceutical products, prompting extensive recalls and suspensions. Valsartan, candesartan, irbesartan, olmesartan, and other sartans have been discovered to have additional nitrosamine impurities, such as N-nitroso-N-methyl-4-aminobutyric acid (NMBA), N-nitroso-Di-isopropyl amine (NDIPA), N-nitroso-Ethyl-Isopropyl amine (NEIPA), and N-nitroso-Diethyl amine (NDEA). Concerns about drug safety have grown in response to reports of nitrosamine contamination in pharmaceuticals, such as pioglitazone, rifampin, rifapentine, and varenicline. This review investigates the occurrence and impact of nitrosamine impurities in sartans and pharmaceutical goods, as well as their underlying causes. The discussion emphasizes the significance of comprehensive risk assessment and mitigation approaches at various phases of medication development and manufacturing. The link between amines and nitrosamine impurities is also investigated, with an emphasis on pH levels and the behaviour of primary, secondary, tertiary, and quaternary amines. Regulations defining standards for nitrosamine assessment and management, such as ICH Q3A-Q3E and ICH M7, are critical in resolving impurity issues. Furthermore, the Global Substance Registration System (GSRS) is underlined as being critical for information sharing and product safety in the pharmaceutical industry. The review specifically focuses on the relationship between ranitidine and N-nitroso dimethyl amine (NDMA) in the context of the implications of nitrosamine contamination on patient safety and medicine supply. The importance of regulatory authorities in discovering and correcting nitrosamine impurities is highlighted in order to improve patient safety, product quality, and life expectancy. Furthermore, the significance of ongoing study and attention to nitrosamine-related repercussions for increasing pharmaceutical safety and overall public health is emphasized.

Impact of ramipril nitroso-metabolites on cancer incidence - in silico and in vitro safety evaluation

Background

Angiotensin-converting enzyme inhibitors (ACE-I) and their pharmacologically related sartans have been associated with an increased cancer incidence in several clinical observations. In 2018, sartans were revealed as being significantly contaminated with nitrosamines. Nitrosamines are potent human mutagens that can be formed ex vivo and, more concerningly, also in vivo from nitrosatable drug precursors. Their formation in sartans may justify the reported cancer risk and, by analogy, this may also apply to ACE-Is.

Materials and methods

We investigated a commonly used ACE-I, ramipril (RAM). We checked its susceptibility to in vivo interaction with nitrite, potentially resulting in the generation of mutagenic N-nitrosamines. To that end, in silico simulation of mutagenicity of RAM nitroso-derivatives was performed using VEGA-GUI software. Then, the Nitrosation Assay Procedure was conducted which served as a model of endogenous reaction. The resulting post-nitrosation mixtures were subjected to a bacterial reverse mutation test employing Salmonella typhimurium strains TA98 and TA100 with and without metabolic activation.

Results

Our results showed that studied samples did not induce point mutations in the test bacteria, regardless of the catalytic cytochrome activity.

Conclusion

We concluded that RAM endogenous nitrosation is not the reason for increased cancer incidence. However, other ACE-Is must be verified in a similar manner.

A deep dive into historical Ames study data for N-nitrosamine compounds

Mutagenicity data is a core component of the safety assessment data required by regulatory agencies for acceptance of new drug compounds, with the OECD-471 bacterial reverse mutation (Ames) assay most widely used as a primary screen to assess drug impurities for potential mutagenic risk. N-Nitrosamines are highly potent mutagenic carcinogens in rodent bioassays and their recent detection as impurities in pharmaceutical products has sparked increased interest in their safety assessment. Previous literature reports indicated that the Ames test might not be sensitive enough to detect the mutagenic potential of N-nitrosamines in order to accurately predict a risk of carcinogenicity. To explore this hypothesis, public Ames and rodent carcinogenicity data pertaining to the N-nitrosamine class of compounds was collated for analysis. Here we present how variations to the OECD 471-compliant Ames test, including strain, metabolic activation, solvent type and pre-incubation/plate incorporation methods, may impact the predictive performance for carcinogenicity. An understanding of optimal conditions for testing of N-nitrosamines may improve both the accuracy and confidence in the ability of the Ames test to identify potential carcinogens.

Does the Red Shift in UV-Vis Spectra Really Provide a Sensing Option for Detection of N-Nitrosamines Using Metalloporphyrins?

N-nitrosamines are widespread cancerogenic compounds in human environment, including water, tobacco products, food, and medicinal products. Their presence in pharmaceuticals has recently led to several recalls of important medicines from the market, and strict controls and tight limits of N-nitrosamines are now required. Analytical determination of N-nitrosamines is expensive, laborious, and time-inefficient making development of simpler and faster techniques for their detection crucial. Several reports published in the previous decade have demonstrated that cobalt porphyrin-based chemosensors selectively bind N-nitrosamines, which produces a red shift of characteristic Soret band in UV-Vis spectra. In this study, a thorough re-evaluation of metalloporphyrin/N-nitrosamine adducts was performed using various characterization methods. Herein, we demonstrate that while N-nitrosamines can interact directly with cobalt-based porphyrin complexes, the red shift in UV-Vis spectra is not selectively assured and might also result from the interaction between impurities in N-nitrosamines and porphyrin skeleton or interaction of other functional groups within the N-nitrosamine structure and the metal ion within the porphyrin. We show that pyridine nitrogen is the interacting atom in tobacco-specific N-nitrosamines (TSNAs), as pyridine itself is an active ligand and not the N-nitrosamine moiety. When using Co(II) porphyrins as chemosensors, acidic and basic impurities in dialkyl N-nitrosamines (e.g., formic acid, dimethylamine) are also UV-Vis spectra red shift-producing species. Treatment of these N-nitrosamines with K2CO3 prevents the observed UV-Vis phenomena. These results imply that cobalt-based metalloporphyrins cannot be considered as selective chemosensors for UV-Vis detection of N-nitrosamine moiety-containing species. Therefore, special caution in interpretation of UV-Vis red shift for chemical sensors is suggested.

Characterizing complex and competing drug-drug interactions between the antiviral regimen of glecaprevir and pibrentasvir with rifampin or carbamazepine

The fixed-dose combination of the direct acting antivirals glecaprevir (GLE) and pibrentasvir (PIB) is an oral, once-daily treatment for all six major genotypes of chronic hepatitis C virus infection. A single and multiple-dose rifampin study (N = 12) and a carbamazepine study (N = 12) were conducted in healthy subjects to evaluate the effects of CYP3A/P-gp induction and OATP inhibition on the pharmacokinetics of GLE and PIB. In study 1, GLE 300 mg + PIB 120 mg was administered as a single dose either alone, after single and multiple daily doses of rifampin 600 mg, or 24 h after the last rifampin dose. In study 2, GLE 300 mg + PIB 120 mg was administered as a single dose either alone or after multiple doses of carbamazepine 200 mg. Relative to GLE + PIB alone, exposure of GLE was significantly increased by the first co-administered rifampin dose due to OATP inhibition, significantly decreased 24 h after the last rifampin dose due to CYP3A/P-gp induction, and slightly increased when co-administered with steady-state rifampin due to a combination of inhibition and induction forces. Exposure of PIB was not affected when co-administered with the first rifampin dose but was significantly decreased with steady-state rifampin co-administration, or 24 h after the last rifampin dose due to P-gp induction. Carbamazepine significantly decreased GLE and PIB exposure, mainly attributed to P-gp induction. The regimens tested were generally well-tolerated by the subjects and no new safety issues were identified.

Strategies for Assessing Acceptable Intakes for Novel N-Nitrosamines Derived from Active Pharmaceutical Ingredients

The detection of N-nitrosamines, derived from solvents and reagents and, on occasion, the active pharmaceutical ingredient (API) at higher than acceptable levels in drug products, has led regulators to request a detailed review for their presence in all medicinal products. In the absence of rodent carcinogenicity data for novel N-nitrosamines derived from amine-containing APIs, a conservative class limit of 18 ng/day (based on the most carcinogenic N-nitrosamines) or the derivation of acceptable intakes (AIs) using structurally related surrogates with robust rodent carcinogenicity data is recommended. The guidance has implications for the pharmaceutical industry given the vast number of marketed amine-containing drugs. In this perspective, the rate-limiting step in N-nitrosamine carcinogenicity, involving cytochrome P450-mediated α-carbon hydroxylation to yield DNA-reactive diazonium or carbonium ion intermediates, is discussed with reference to the selection of read-across analogs to derive AIs. Risk-mitigation strategies for managing putative N-nitrosamines in the preclinical discovery setting are also presented.

The Landscape of Potential Small and Drug Substance Related Nitrosamines in Pharmaceuticals

This article reports the outcome of an in silico analysis of more than 12,000 small molecule drugs and drug impurities, identifying the nitrosatable structures, assessing their potential to form nitrosamines under relevant conditions and the challenges to determine compound-specific AIs based on data available or read-across approaches for these nitrosamines and their acceptance by health authorities. Our data indicate that the presence of nitrosamines in pharmaceuticals is likely more prevalent than originally expected. In total, 40.4 % of the analyzed APIs and 29.6 % of the API impurities are potential nitrosamine precursors. Most structures identified through our workflow could form complex API-related nitrosamines, so-called nitrosamine drug substance related impurities (NDSRIs), although we also found structures that could release the well-known small and potent nitrosamines NDMA, NDEA, and others. Due to common structural motifs including secondary or tertiary amine moieties, whole essential drug classes such as beta blockers and ACE inhibitors are at risk. To avoid the risk of drug shortages or even the complete loss of therapeutic options, it will be essential that the well-established ICH M7 principles remain applicable for nitrosamines and that that the industry and regulatory authorities keep an open communication not only about the science but also to make sure there is a good balance between risk and benefit to patients.

A Genetic Toxicology Study of the Rapid Detection of Nitrosamine Compounds by the rpsL Gene Mutation Assay

In a rpsL gene mutation experiment, the mutagenicity of the nitrosamine compounds N-diethylnitrosamine (NDEA) and N-dipropylnitrosamine (NDPA) was investigated at the cellular level, as well as with PCR (polymerase chain reaction) and RCA (rolling-circle amplification) amplification systems. The experiments were set up with 10 ppm, 100 ppm, and 1000 ppm concentration gradients of NDEA and NDPA, and ethidium bromide (EB) was used as a positive control group. The results demonstrated that the mutagenic frequency of NDEA and NDPA was significantly higher than the spontaneous mutation frequency of the rpsL gene under the same conditions, but lower than the mutagenic rate of EB in the positive control, and there was a dose-effect relationship, indicating that NDEA and NDPA could induce rpsL gene mutation. The rpsL mutation system has a low spontaneous mutation background and high sensitivity, thus the system is expected to become an effective tool for the rapid detection of carcinogens in the field of food.

Practical and Science-Based Strategy for Establishing Acceptable Intakes for Drug Product N-Nitrosamine Impurities

The potential for N-nitrosamine impurities in pharmaceutical products presents a challenge for the quality management of medicinal products. N-Nitrosamines are considered cohort-of-concern compounds due to the potent carcinogenicity of many of the structurally simple chemicals within this structural class. In the past 2 years, a number of drug products containing certain active pharmaceutical ingredients have been withdrawn or recalled from the market due to the presence of carcinogenic low-molecular-weight N,N-dialkylnitrosamine impurities. Regulatory authorities have issued guidance to market authorization holders to review all commercial drug substances/products for the potential risk of N-nitrosamine impurities, and in cases where a significant risk of N-nitrosamine impurity is identified, analytical confirmatory testing is required. A key factor to consider prior to analytical testing is the estimation of the daily acceptable intake (AI) of the N-nitrosamine impurity. A significant proportion of N-nitrosamine drug product impurities are unique/complex structures for which the development of low-level analytical methods is challenging. Moreover, these unique/complex impurities may be less potent carcinogens compared to simple nitrosamines. In the present work, our objective was to derive AIs for a large number of complex N-nitrosamines without carcinogenicity data that were identified as potential low-level impurities. The impurities were first cataloged and grouped according to common structural features, with a total of 13 groups defined with distinct structural features. Subsequently, carcinogenicity data were reviewed for structurally related N-nitrosamines relevant to each of the 13 structural groups and group AIs were derived conservatively based on the most potent N-nitrosamine within each group. The 13 structural group AIs were used as the basis for assigning AIs to each of the structurally related complex N-nitrosamine impurities. The AIs of several N-nitrosamine groups were found to be considerably higher than those for the simple N,N-dialkylnitrosamines, which translates to commensurately higher analytical method detection limits.

Risk assessment for nitrosated pharmaceuticals: A future perspective in drug development

Since June 2018, thousands of drug products from around the world had to be recalled due to the unexpected presence of nitrosamines (NAs). Starting with the pharmaceutical group of sartans, antidiabetic drugs, antihistamines, and antibiotics also became the subject of investigation. The occurrence of NAs has shown that pharmaceutical companies and regulatory agencies did not focus on these substances in the past during drug development. In this study, we incorporated a nitrosation assay procedure into high-resolution supercritical fluid chromatography (SFC)-mass spectrometry screening to test the potential of direct nitrosation of active pharmaceutical ingredients (APIs). The forced degradation study was performed with a four-fold molar excess of sodium nitrite, relative to the drug substance, at pH 3-4 for 4 h at 37°C. Chromatographic separation was performed on a porous graphitic carbon column by SFC. The mass analysis then focused on direct N-nitrosation or N-nitroso compounds (NOCs) formed after dealkylation. Substances (n = 67) from various pharmaceutical classes were evaluated and 49.3% of them formed NOCs, of which 21.2% have not yet been reported in the literature. In addition, for two APIs, which are known to form an unidentified NOC, the structure could be identified. A few substances also showed multiple NOCs and even N,N'-dinitroso-species. As NAs are carcinogens, they have to be eliminated or at least limited to prevent cancer in patients, who rely on these drugs. This study contributes a procedure that can be implemented in preapproval drug development and postapproval risk assessment to prevent unexpected findings in the future.

Estimated Cancer Risks Associated with Nitrosamine Contamination in Commonly Used Medications

Many nitrosamines are potent carcinogens, with more than 30 listed under California's Proposition 65. Recently, nitrosamine contamination of commonly used drugs for treatment of hypertension, heartburn, and type 2 diabetes has prompted numerous Food and Drug Administration (FDA) recalls in the US. These contaminants include the carcinogens NDMA (N-nitrosodimethylamine) and NDEA (N-nitrosodiethylamine) and the animal tumorigen NMBA (N-nitroso-N-methyl-4-aminobutyric acid). NMBA and NDEA are metabolically and/or structurally related to NDMA, an N-nitrosomethyl-n-alkylamine (NMA), and 12 other carcinogenic NMAs. These nitrosamines exhibit common genotoxic and tumorigenic activities, with shared target tumor sites amongst chemicals and within a given laboratory animal species. We use the drug valsartan as a case study to estimate the additional cancer risks associated with NDMA and NDEA contamination, based on nitrosamine levels reported by the US FDA, cancer potencies developed by California's Proposition 65 program and the US Environmental Protection Agency (EPA), and specific exposure scenarios. These estimates suggest that nitrosamine contamination in drugs that are used long-term can increase cancer risks and pose a serious concern to public health.

Simultaneous Estimation of Six Nitrosamine Impurities in Valsartan Using Liquid Chromatographic Method

BACKGROUND

Nitrosamine impurities are potent carcinogens in animals and probable carcinogens in humans. In current scenario, there is a need for effective analytical methods to detect and identify various nitrosamine impurities, and to develop rapid solutions to ensure the safety and quality of the drugs.

OBJECTIVE

In present work, liquid chromatographic method was developed for estimation of six nitrosamine impurities in Valsartan.

METHODS

The developed method employed C18 (250 × 4.6 mm, 5 μ) column as a stationary phase, combination of acetonitrile, water (pH 3.2 adjusted with formic acid) and methanol with gradient elution as mobile phase and 228 nm as detection wavelength. Developed method was validated as per ICH Q2(R1) guideline. Method was successfully applied to estimate six nitrosamine impurities in Valsartan API and formulation (tablets).

RESULTS

Method was able to separate each impurity and Valsartan with resolved and sharp peaks. Results indicated that developed method is linear in selected ranges (coefficient of regressions > 0.9996), precise (RSD < 2%), accurate (recovery in a range of 99.02-100.16%), sensitive (low detection and quantitation limits) and specific for estimation of each impurity in Valsartan. Assay results were found in agreement with the amount of each impurity spiked.

CONCLUSION

Developed method can be applied for simultaneous estimation of six nitrosamine impurities in Valsartan raw material, tablets and fixed dose combination at very low level.

HIGHLIGHTS

Development, validation and application of HPLC method for estimation of six nitrosamine impurities in Valsartan API and formulation samples.