Short commentary on NDMA (N-nitrosodimethylamine) contamination of valsartan products

Development of a Simultaneous Analytical Method for Amines Corresponding to 10 Typical Nitrosamines

Regulatory authorities in various countries have successively issued notices and guidance to pharmaceutical manufacturers and distributors to evaluate the risk of contamination of nitrosamines in pharmaceutical products and to take appropriate measures. Analysis of nitrosamines in pharmaceutical products is not easy due to the large number of foreign substances, and the risk of contamination is determined by first conducting a desk investigation of the manufacturing process of the APIs or pharmaceutical products. However, a desk investigation may miss the risk since this method is not based on actual measurements. Therefore, in addition to conventional desk-based investigation, a new method is required to pick up risks that cannot be covered by a desk investigation. Nitrosamines are known to be formed by the reaction of amines with nitrosating agents such as nitrite. In the case of small alkyl nitrosamines such as NDMA and NDEA, the origin of the amines is mostly residual amines in the APIs. Residual amines in the APIs are a potential nitrosamine contamination risk, although the extent of that risk has rarely been reported. In this study, we developed and validated a simultaneous analytical method for amines corresponding to 10 typical small alkyl nitrosamines. Good linearity was obtained in the range of 0.003 to 10 μg/mL for MPA, 0.003 to 2 μg/mL for DIPA and DBA, 0.003 to 1 μg/mL for MeP, DEA, EIPA, and DPA, and 0.003 to 0.2 μg/mL for DMA, MOR, and MBA. The limits of quantitation and detection were 0.003 and 0.001-0.003 μg/mL, respectively. The recovery rates ranged from 70 to 130% for 121 APIs and were more than 40% for 83 APIs. Repeatability was also good, with %RSD < 15%. Although the correlation between the amount of amines detected in the APIs and the nitrosamines in the pharmaceutical products is under investigation, we expect that this analytical method will be used to determine the residual amine contents in APIs and contribute to the risk assessment of the nitrosamine contamination.

Genotoxic effects of NDMA-contaminated ranitidine on Allium cepa cells and unveiling carcinogenic mechanisms via DFT and molecular dynamics simulation study

This study investigated the potential genotoxic and carcinogenic effects of N-nitrosodimethylamine (NDMA), a hazardous compound found in ranitidine formulations that are used to treat excessive stomach acid. The study first examined the effects of NDMA-contaminated ranitidine formulation on Allium cepa root growth and mitotic activity. The results demonstrated dose-dependent decreases in both root growth and mitotic index indicating genotoxicity and cell division disruption. Elevated concentrations of ranitidine correlated with increased chromosomal aberrations indicating genotoxic capabilities. These outcomes underscored that NDMA contaminated ranitidine exposure triggers genotoxicity hampering cell division and inducing chromosomal aberrations. Electronic characteristics of NDMA revealed its electrophilic nature suggesting its capability to create covalent adducts with DNA bases fostering genotoxic and carcinogenic characteristics. Molecular docking analysis showed the interactions of NDMA with DNA including hydrogen bonds and carbon-hydrogen interactions with nucleotide bases forming DNA adducts. Molecular dynamics simulations showcased the dynamic behavior of the DNA-NDMA complex over time with structural fluctuations. Dynamic hydrogen bond fluctuations implied interactive intricacies between solute and solvent molecules. Overall, this study illuminates how NDMA-contaminated ranitidine could trigger DNA damage and potentially contribute to carcinogenesis. It emphasizes the urgency of minimizing exposure to this perilous and hazardous compound.

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.

Quantum chemical calculations of nitrosamine activation and deactivation pathways for carcinogenicity risk assessment

N-nitrosamines and nitrosamine drug substance related impurities (NDSRIs) became a critical topic for the development and safety of small molecule medicines following the withdrawal of various pharmaceutical products from the market. To assess the mutagenic and carcinogenic potential of different N-nitrosamines lacking robust carcinogenicity data, several approaches are in use including the published carcinogenic potency categorization approach (CPCA), the Enhanced Ames Test (EAT), in vivo mutagenicity studies as well as read-across to analogue molecules with robust carcinogenicity data. We employ quantum chemical calculations as a pivotal tool providing insights into the likelihood of reactive ion formation and subsequent DNA alkylation for a selection of molecules including e.g., carcinogenic N-nitrosopiperazine (NPZ), N-nitrosopiperidine (NPIP), together with N-nitrosodimethylamine (NDMA) as well as non-carcinogenic N-nitrosomethyl-tert-butylamine (NTBA) and bis (butan-2-yl) (nitros)amine (BBNA). In addition, a series of nitroso-methylaminopyridines is compared side-by-side. We draw comparisons between calculated reaction profiles for structures representing motifs common to NDSRIs and those of confirmed carcinogenic and non-carcinogenic molecules with in vivo data from cancer bioassays. Furthermore, our approach enables insights into reactivity and relative stability of intermediate species that can be formed upon activation of several nitrosamines. Most notably, we reveal consistent differences between the free energy profiles of carcinogenic and non-carcinogenic molecules. For the former, the intermediate diazonium ions mostly react, kinetically controlled, to the more stable DNA adducts and less to the water adducts via transition-states of similar heights. Non-carcinogenic molecules yield stable carbocations as intermediates that, thermodynamically controlled, more likely form the statistically preferred water adducts. In conclusion, our data confirm that quantum chemical calculations can contribute to a weight of evidence approach for the risk assessment of nitrosamines.

Evaluation of the nitrosamine impurities of ACE inhibitors using computational, in vitro, and in vivo methods demonstrate no genotoxic potential

Evaluation and mitigation of the potential carcinogenic risks associated with nitrosamines in marketed pharmaceutical products are areas of interest for pharmaceutical companies and health authorities alike. Significant progress has been made to establish acceptable intake (AI) levels for N-nitrosamine drug substance-related impurities (NDSRIs) using SAR, however some compounds require experimental data to support derivation of a recommended AI. Many angiotensin-converting enzyme inhibitors, identified by the suffix "pril," have secondary amines that can potentially react to form nitrosamines. Here we consider a structural assessment and metabolism data, coupled with comprehensive in vitro and in vivo (mouse) genotoxicity testing to evaluate this particular class of nitrosamines. N-nitroso ramipril and N-nitroso quinapril, both of which are predicted to have inhibited nitrosamine bioactivation due to steric hinderance and branching at the α-position were non-genotoxic in the in vivo liver comet assay and non-mutagenic in the in vivo Big Blue® mutation and duplex sequencing assays. Predicted metabolism along with in vitro metabolism data and quantum chemical calculations related to DNA interactions offer a molecular basis for the negative results observed in both in vitro and in vivo testing. These nitrosamines are concluded to be non-mutagenic and non-carcinogenic; therefore, they should be controlled according to ICH Q3B guidance. Furthermore, these results for N-nitroso ramipril and N-nitroso quinapril should be considered when evaluating the appropriate AI and control strategy for other structurally similar "pril" NDSRIs.

Investigation of the Formaldehyde-Catalyzed NNitrosation of Dialkyl Amines: An Automated Experimental and Kinetic Modelling Study Using Dibutylamine

The potential for drug substances and drug products to contain low levels of N-nitrosamines is of continued interest to the pharmaceutical industry and regulatory authorities. Acid-promoted nitrosation mechanisms in solution have been investigated widely in the literature and are supported by kinetic modelling studies. Carbonyl compounds, particularly formaldehyde, which may be present as impurities in excipients and drug product packaging components or introduced during drug substance manufacturing processes are also known to catalyze nitrosation, but their impact on the risk of N-nitrosamine formation has not been systematically investigated to date. In this study, we experimentally investigated the multivariate impact of formaldehyde, nitrite and pH on N-nitrosation in aqueous solution using dibutylamine as a model amine. We augmented a published kinetic model by adding formaldehyde-catalyzed nitrosation reactions. We validated the new kinetic model vs. the experimental data and then used the model to systematically investigate the impact of formaldehyde levels on N-nitrosamine formation. Simulations of aqueous solution systems show that at low formaldehyde levels the formaldehyde-catalyzed mechanisms are insignificant in comparison to other routes. However, formaldehyde-catalyzed mechanisms can become more significant at neutral and high pH under higher formaldehyde levels. Model-based sensitivity analysis demonstrated that under high nitrite levels and low formaldehyde levels (where the rate of formaldehyde-catalyzed nitrosation is low compared to the acid-promoted pathways) the model can be used with kinetic parameters for model amines in the literature without performing additional experiments to fit amine-specific parameters. For other combinations of reaction parameters containing formaldehyde, the formaldehyde-catalyzed kinetics are non-negligible, and thus it is advised that, under such conditions, additional experiments should be conducted to reliably use the model.

Simple and Practical Method for the Quantitative High-Sensitivity Analysis of N-Nitroso Duloxetine in Duloxetine Drug Products Utilizing LC-MS/MS

The high-sensitivity analytical method for the determination of N-nitroso duloxetine (NDXT), which can be carcinogenic and harmful in duloxetine drug products, was successfully developed utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS). Tandem mass spectrometric detection at positive electrospray ionization in multiple reaction monitoring (MRM) mode was then employed for the determination of NDXT. The quantitative range for NDXT was found in 0.075-3.75 ng/mL in terms of concentration in the dilution solvent for duloxetine active pharmaceutical ingredient (API) and capsules and 0.075-1.875 ng/mL for duloxetine tablets, and the recovery rates were in the range of 82.5-91.6% for the API, 91.0-113.4% for capsules, and 70.6-109.1% for tablets, respectively. The repeatability was 6.9% with a %RSD of n = 9 for the API, 10.9% with a %RSD of n = 9 for capsules, and 21.6% with a %RSD of n = 9 for tablets, respectively. For reproducibility, the %RSD of the n = 6 measurements between the two sites was 3.5%. The calibration curve of NDXT in the concentration range of 0.075-3.75 ng/mL was carried out, and the correlation coefficient (R) was found to be 1.000. The sample solution was stable for 7 days. The applicability of the determination of the content of NDXT in a variety of duloxetine drug products was demonstrated. This manuscript seeks to aid the risk assessment process of NDXT in duloxetine drug products through providing a fast and reliable quantitative LC-MS/MS analytical method.

Ames test study designs for nitrosamine mutagenicity testing: qualitative and quantitative analysis of key assay parameters

The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug product withdrawals. NAs belong to the 'cohort of concern' list of genotoxic impurities (ICH M7) because of the mutagenic and carcinogenic potency of this chemical class. In addition, regulatory concerns exist regarding the capacity of the Ames test to predict the carcinogenic potential of NAs because of historically discordant results. The reasons postulated to explain these discordant data generally point to aspects of Ames test study design. These include vehicle solvent choice, liver S9 species, bacterial strain, compound concentration, and use of pre-incubation versus plate incorporation methods. Many of these concerns have their roots in historical data generated prior to the harmonization of Ames test guidelines. Therefore, we investigated various Ames test assay parameters and used qualitative analysis and quantitative benchmark dose modelling to identify which combinations provided the most sensitive conditions in terms of mutagenic potency. Two alkyl-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were studied. NDMA and NDEA mutagenicity was readily detected in the Ames test and key assay parameters were identified that contributed to assay sensitivity rankings. The pre-incubation method (30-min incubation), appropriate vehicle (water or methanol), and hamster-induced liver S9, alongside Salmonella typhimurium strains TA100 and TA1535 and Escherichia coli strain WP2uvrA(pKM101) provide the most sensitive combination of assay parameters in terms of NDMA and NDEA mutagenic potency in the Ames test. Using these parameters and further quantitative benchmark dose modelling, we show that N-nitrosomethylethylamine (NMEA) is positive in Ames test and therefore should no longer be considered a historically discordant NA. The results presented herein define a sensitive Ames test design that can be deployed for the assessment of NAs to support robust impurity qualifications.

On-column trace-level formation of N-nitrosamine in a liquid chromatography-mass spectrometry analytical system

A model reaction between di-n-butylamine and sodium nitrite was studied to investigate trace-level N-nitrosamine formation. Liquid chromatography-mass spectrometry (LC-MS) analysis of kinetic time points from an in-progress reaction showed a systematic offset in nitrosamine concentration between quenched and unquenched samples. By combining samples of amine and nitrite in the needle of the autosampler it was demonstrated that N-nitrosamine was formed in the LC-MS system. Further experimentation indicated that nitrosation was occurring on-column.

Risk characterization of N-nitrosodimethylamine in pharmaceuticals

Since 2018, N-nitrosodimethylamine (NDMA) has been a reported contaminant in numerous pharmaceutical products. To guide the pharmaceutical industry, FDA identified an acceptable intake (AI) of 96 ng/day NDMA. The approach assumed a linear extrapolation from the Carcinogenic Potency Database (CPDB) harmonic-mean TD50 identified in chronic studies in rats. Although NDMA has been thought to act as a mutagenic carcinogen in experimental animals, it has not been classified as a known human carcinogen by any regulatory agency. Humans are exposed to high daily exogenous and endogenous doses of NDMA. Due to the likelihood of a threshold dose for NDMA-related tumors in animals, we believe that there is ample scientific basis to utilize the threshold-based benchmark dose or point-of-departure (POD) approach when estimating a Permissible Daily Exposure limit (PDE) for NDMA. We estimated that 29,000 ng/kg/day was an appropriate POD for calculating a PDE. Assuming an average bodyweight of 50 kg, we expect that human exposures to NDMA at doses below 5800 ng/day in pharmaceuticals would not result in an increased risk of liver cancer, and that there is little, if any, risk for any other type of cancer, when accounting for the mode-of-action in humans.

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.

Bumetanide as a Model NDSRI Substrate: N-nitrosobumetanide Impurity Formation and its Inhibition in Bumetanide Tablets

Nitrosamine compounds are classified as potential human carcinogens, the origin of these impurities can be broadly classified in two categories, nitrosamine impurity found in drug products that are not associated with the Active Pharmaceutical Ingredient (API), such as N-nitrosodimethylamine (NDMA) or nitrosamine impurities associated with the API, such as nitrosamine drug substance-related impurities (NDSRIs). The mechanistic pathway for the formation of these two classes of impurities can be different and the approach to mitigate the risk should be tailored to address the specific concern. In the last couple of years number of NDSRIs have been reported for different drug products. Though, not the only contributing factor for the formation of NDSIRs, it is widely accepted that the presence of residual a nitrites/nitrates in the components used in the manufacturing of the drug products can be the primary contributor to the formation of NDSRIs. Approaches to mitigate the formation of NDSRIs in drug products include the use of antioxidants or pH modifiers in the formulation. The primary objective of this work was to evaluate the role of different inhibitors (antioxidants) and pH modifiers in tablet formulations prepared in-house using bumetanide (BMT) as a model drug to mitigate the formation of N-nitrosobumetanide (NBMT). A multi-factor study design was created, and several bumetanide formulations were prepared by wet granulation with and without sodium nitrite spike (100 ppm) and different antioxidants (ascorbic acid, ferulic acid or caffeic acid) at three concentrations (0.1%, 0.5% or 1% of the total tablet weight). Formulations with acidic and basic pH were also prepared using 0.1 N hydrochloric acid and 0.1 N sodium bicarbonate, respectively. The formulations were subjected to different storage (temperature and humidity) conditions over 6 months and stability data was collected. The rank order of N-nitrosobumetanide inhibition was highest with alkaline pH formulations, followed by formulations with ascorbic acid, caffeic acid or ferulic acid present. In summary, we hypothesize that maintaining a basic pH or the addition of an antioxidant in the drug product can mitigate the conversion of nitrite to nitrosating agent and thus reduce the formation of bumetanide nitrosamines.

Molecular origins of mutational spectra produced by the environmental carcinogen N-nitrosodimethylamine and SN1 chemotherapeutic agents

DNA-methylating environmental carcinogens such as N-nitrosodimethylamine (NDMA) and certain alkylators used in chemotherapy form O 6-methylguanine (m6G) as a functionally critical intermediate. NDMA is a multi-organ carcinogen found in contaminated water, polluted air, preserved foods, tobacco products, and many pharmaceuticals. Only ten weeks after exposure to NDMA, neonatally-treated mice experienced elevated mutation frequencies in liver, lung and kidney of ∼35-fold, 4-fold and 2-fold, respectively. High-resolution mutational spectra (HRMS) of liver and lung revealed distinctive patterns dominated by GC→AT mutations in 5'-Pu-G-3' contexts, very similar to human COSMIC mutational signature SBS11. Commonly associated with alkylation damage, SBS11 appears in cancers treated with the DNA alkylator temozolomide (TMZ). When cells derived from the mice were treated with TMZ, N-methyl-N-nitrosourea, and streptozotocin (two other therapeutic methylating agents), all displayed NDMA-like HRMS, indicating mechanistically convergent mutational processes. The role of m6G in shaping the mutational spectrum of NDMA was probed by removing MGMT, the main cellular defense against m6G. MGMT-deficient mice displayed a strikingly enhanced mutant frequency, but identical HRMS, indicating that the mutational properties of these alkylators is likely owed to sequence-specific DNA binding. In sum, the HRMS of m6G-forming agents constitute an early-onset biomarker of exposure to DNA methylating carcinogens and drugs.

Acceptable Intakes (AIs) for 11 Small molecule N-nitrosamines (NAs)

Low levels of N-nitrosamines (NAs) were detected in pharmaceuticals and, as a result, health authorities (HAs) have published acceptable intakes (AIs) in pharmaceuticals to limit potential carcinogenic risk. The rationales behind the AIs have not been provided to understand the process for selecting a TD₅₀ or read-across analog. In this manuscript we evaluated the toxicity data for eleven common NAs in a comprehensive and transparent process consistent with ICH M7. This evaluation included substances which had datasets that were robust, limited but sufficient, and substances with insufficient experimental animal carcinogenicity data. In the case of robust or limited but sufficient carcinogenicity information, AIs were calculated based on published or derived TD₅₀s from the most sensitive organ site. In the case of insufficient carcinogenicity information, available carcinogenicity data and structure activity relationships (SARs) were applied to categorical-based AIs of 1500 ng/day, 150 ng/day or 18 ng/day; however additional data (such as biological or additional computational modelling) could inform an alternative AI. This approach advances the methodology used to derive AIs for NAs.

A collaborative study of the impact of N-nitrosamines presence and ARB recall on ARB utilization - results from IQVIA™ Disease Analyzer Germany

PURPOSE

Regulators are increasingly concerned with  the impact of recalls on drug adherence. In 2018, N-nitrosamines impurities were detected in valsartan containing medical products. Concerned products were immediately recalled in July 2018 by regulatory agencies internationally. In Germany, recalls were issued for valsartan, losartan and irbesartan from July 2018 to March 2019. This study examined angiotensin II receptor blocker (ARB) utilization trends and switching patterns in Germany before and after July 2018.

METHODS

Patients prescribed ARBs from January 2014 to June 2020 in general practices in Germany were included in a collaborative framework common protocol drug utilization study led by the US Food and Drug Administration. Trends in monthly and quarterly proportions of total ARB prescribing were analysed for individual ARBs using descriptive statistics and interrupted time series analysis. The rate of switching to an alternative ARB was analysed before and after the recalls.

RESULTS

The proportion of valsartan prescriptions immediately decreased from 35.9 to 17.8% following the first recalls in July 2018, mirrored by an increased proportion for candesartan. Increased switching from valsartan to candesartan was observed. No increased switching was observed after losartan recalls, whereas for irbesartan, increased switching was observed 6-12 months after the last recall. Increased switching from ARBs to angiotensin-converting enzyme (ACE) inhibitors or ARB treatment discontinuations were not observed.

CONCLUSION

This study showed that patients were able to continue ARB treatment despite the July 2018-March 2019 recalls, although many patients needed to switch to an alternative ARB. The duration of the impact of ARB recalls appeared to be limited.

Comprehensive computational study on reaction mechanism of N-Nitroso dimethyl amine formation from substituted hydrazine derivatives during ozonation

N- Nitrosodimethyl amine, the simplest member of the N-Nitrosamine family, is a carcinogenic and mutagenic agent that has gained considerable research interest owing to its toxic nature. Ozonation of industrially important hydrazines, such as unsymmetrical dimethylhydrazine (UDMH) or monomethylhydrazine (MMH), has been associated with NDMA formation and accumulation in the environment. UDMH/MMH - ozonation also leads to several other transformation products such as acetaldehyde dimethyl hydrazine (ADMH), tetramethyl tetra azene (TMT), diazomethane, methyl diazene, etc, which can be either precursors or competitors for NDMA formation. However, the relevant chemistry detailing the formation of these transformation products from UDMH/MMH -ozone reaction and their subsequent conversion to NDMA is not well understood. In this work, we explored the formation mechanism of ADMH and TMT from UDMH-ozonation and their further oxidation to NDMA using the second-order Moller Plesset perturbation theory employing the 6-311G(d) basis set. We have also investigated how MMH selectively forms methyl diazene and diazomethane under normal conditions and NDMA in the presence of excess ozone. Our calculations indicate that the reactions proceed via an initial H abstraction from the hydrazine -NH2 group, followed by the oxidation of the generated N-radical species. The formation of ADMH from the UDMH-ozone reaction involves an acetaldehyde intermediate, which then reacts with a second UDMH molecule to generate ADMH. The preferable attack of ozone molecule on N=C bond of ADMH generates DMAN intermediate, which subsequently undergoes oxidation to form NDMA. Unlike other transformation products, TMT formation occurs via the dimerization of DMAN. 1Though there exists an N=N bond in the TMT, which are preferable attacking sites for ozone, experimental studies show the lower yields of NDMA formation, which corroborates with the high activation barrier required for the process (42 kcal/mol). Overall, our calculated results agree well with the experimental observations and rate constants. Computational calculations bring new insights into the electronic nature and kinetics of the elementary reactions of this pathway, enabled by computed energies of structures that are not possible to access experimentally.

N-Nitrosamine Formation in Pharmaceutical Solid Drug Products: Experimental Observations

The potential presence of N-nitrosamines in medicinal products has become a matter of concern for health authorities and pharmaceutical companies. However, very little information is available in published literature on N-nitrosamine formation within pharmaceutical drug products. In response, experiments were undertaken to test if secondary and tertiary amines present in solid drug products could undergo nitrosation due to the presence of nitrite in the excipients used in the manufacture of the drug product. This work focused on solid dosage forms exploring several model amines of varying chemical structure, solubility and pKa which were formulated using common excipients with and without added nitrite. Monitoring the formation of the N-nitrosamines after processing and upon stressed stability conditions showed that N-nitrosamine formation can occur in solid drug product formulations. The results show that the rate and extent of N-nitrosamine formation depend upon the solubility of the amine, level of nitrite, expected local acidity in water layers within the drug product and mode of processing. Our findings agree with the rank order of dosage form risk from the published EFPIA workflows for quality risk management of N-nitrosamine risks in medicines (EFPIA, 2022): amorphous > wet granulation > direct compression > dry blends. In all cases the level of N-nitrosamine formation in solid dosage forms plateaued at a level that was significantly lower than the maximum theoretical yield based on the level of nitrite present. Trace secondary amine impurities were shown to be a significantly lower risk relative to cases containing a secondary amine present at drug substance levels. A comparison of secondary and simple tertiary alkylamine reactivity showed the tertiary amine to be significantly less reactive with nitrite.

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.

Prevalence of nitrosamine contaminants in drug samples: Has the crisis been overcome?

Various drug samples (N = 249; drug substances, tablets, capsules, solutions, crèmes, and more) from the European pharmaceutical market were collected since 2019 and analyzed for 16 nitrosamines (NAs). In 2.0% of the cases, NAs were detected. These findings included four active pharmaceutical ingredients already known for potential NA contamination: losartan (N-nitrosodimethylamine [NDMA] and N-nitrosodiethylamine, simultaneously), valsartan (NDMA), metformin (NDMA) and ranitidine (NDMA). The fifth new finding, which has not been reported yet, discovered contamination of a molsidomine tablet sample with N-nitrosomorpholine (NMor). The tablet contained 144% of the toxicological allowable intake for NMor. NMor was included in our screening from the beginning and is currently the focus of regulatory authorities, but was added to the guidelines only last year. Thus, it may not have been the focus of regulatory investigations for too long. Our results indicate that the majority of drug products in the market are nonhazardous in terms of patient safety and drug purity. Unfortunately, the list of individual affected products keeps growing constantly and new NA cases, such as molsidomine or nitrosated drug substances (nitrosamine drug substance-related impurities [NDSRI]), continue to emerge. We therefore expect nitrosamine screenings to remain a high priority.

N-nitrosodimethylamine-Contaminated Valsartan and Risk of Cancer: A Nationwide Study of 1.4 Million Valsartan Users

Background Since July 2018, numerous lots of valsartan have been found to be contaminated with N-nitrosodimethylamine (NDMA). We aimed to assess the association between exposure to valsartan products contaminated with NDMA and the risk of cancer. Methods and Results This study was based on data from the Système National des Données de Santé, which is a national database that includes all French residents' health-related expenses. The target population was consumers of valsartan between January 1, 2013 and December 31, 2017, aged between 40 and 80 years old. The association of exposure to contaminated valsartan with the occurrence of any malignancy and cancer by location was evaluated by fitting Cox proportional hazards models weighted by the inverse probability of treatment. A total of 1.4 million subjects without any history of cancer were included. A total of 986 126 and 670 388 patients were exposed to NDMA-contaminated and uncontaminated valsartan, respectively. The use of the NDMA-contaminated valsartan did not increase the overall risk of cancer (adjusted hazard ratio [aHR], 0.99 [95% CI, 0.98-1.0]). However, exposed patients had a higher risk of liver cancer (aHR, 1.12 [95% CI, 1.04-1.22]) and melanoma (aHR, 1.10 [95% CI, 1.03-1.18]). We estimated a mean of 3.7 and 5.8 extra cases per year per 100 000 person-years of liver cancer and melanoma, respectively. Conclusions Our study was the largest to date to examine cancer risks associated with exposure to NDMA-contaminated valsartan. Our findings suggest a slight increased risk of liver cancer and melanoma in patients exposed to NDMA in regularly taken medications.

Rapid Quantitation of Four Nitrosamine Impurities in Angiotensin Receptor Blocker Drug Substances

Starting in July 2018, the FDA alerted patients and health care professionals to the recall of ARBs such as valsartan by several pharmaceutical companies because of their potential contamination with carcinogenic nitrosamine impurities, including: (1) N-nitrosodimethylamine (NDMA), (2) N-nitrosodiethylamine (NDEA), (3) N-nitrosoethylisopropylamine (NEIPA), (4) N-nitrosodiisopropylamine (NDIPA), (5) N-nitrosodibutylamine (NDBA) and (6) N-nitroso-N-methyl-4-aminobutyric acid (NMBA). The FDA initiated a laboratory investigation to develop analytical procedures to test multiple lots of marketed ARB drugs to determine the possible presence of carcinogenic impurities and, if present, quantitate the levels of these impurities. Here the FDA laboratory developed and validated an automated micro-solid phase extraction MS/MS method, where all the analytes are not separated prior to elution to the MS, to simultaneously quantify NEIPA, NDIPA, NDBA and NMBA in ARB drug substances with an instrument sample analysis time of 12 seconds. The method was validated according to the ICH Q2(R1) guideline, and was determined to be specific, accurate, precise and linear over the corresponding nitrosamine analytical ranges. The method has been successfully implemented to quantitate the four nitrosamine impurities in 129 generic losartan, valsartan, olmesartan, irbesartan and telmisartan drug substance samples from 32 lots; and 32 losartan and valsartan drug product samples from 6 lots.

Predicting DNA-Reactivity of N-Nitrosamines: A Quantum Chemical Approach

N-Nitrosamines (NAs) are a class of reactive organic chemicals that humans may be exposed to from environmental sources, food but also impurities in pharmaceutical preparations. Some NAs were identified as DNA-reactive mutagens and many of those have been classified as probable human carcinogens. Beyond high-potency mutagenic carcinogens that need to be strictly controlled, NAs of low potency need to be considered for risk assessment as well. NA impurities and nitrosylated products of active pharmaceutical ingredients (APIs) often arise from production processes or degradation. Most NAs require metabolic activation to ultimately become carcinogens, and their activation can be appropriately described by first-principles computational chemistry approaches. To this end, we treat NA-induced DNA alkylation as a series of subsequent association and dissociation reaction steps that can be calculated stringently by density functional theory (DFT), including α-hydroxylation, proton transfer, hydroxyl elimination, direct S_N2/S_NAr DNA alkylation, competing hydrolysis and S_N1 reactions. Both toxification and detoxification reactions are considered. The activation reactions are modeled by DFT at a high level of theory with an appropriate solvent model to compute Gibbs free energies of the reactions (thermodynamical effects) and activation barriers (kinetic effects). We study congeneric series of aliphatic and cyclic NAs to identify trends. Overall, this work reveals detailed insight into mechanisms of activation for NAs, suggesting that individual steric and electronic factors have directing and rate-determining influence on the formation of carbenium ions as the ultimate pro-mutagens and thus carcinogens. Therefore, an individual risk assessment of NAs is suggested, as exemplified for the complex API-like 4-(N-nitroso-N-methyl)aminoantipyrine which is considered as low-potency NA by in silico prediction.

Use of the bacterial reverse mutation assay to predict carcinogenicity of N-nitrosamines

Under ICH M7, impurities are assessed using the bacterial reverse mutation assay (i.e., Ames test) when predicted positive using in silico methodologies followed by expert review. N-Nitrosamines (NAs) have been of recent concern as impurities in pharmaceuticals, mainly because of their potential to be highly potent mutagenic carcinogens in rodent bioassays. The purpose of this analysis was to determine the sensitivity of the Ames assay to predict the carcinogenic outcome with curated proprietary Vitic (n = 131) and Leadscope (n = 70) databases. NAs were selected if they had corresponding rodent carcinogenicity assays. Overall, the sensitivity/specificity of the Ames assay was 93-97% and 55-86%, respectively. The sensitivity of the Ames assay was not significantly impacted by plate incorporation (84-89%) versus preincubation (82-89%). Sensitivity was not significantly different between use of rat and hamster liver induced S9 (80-93% versus 77-96%). The sensitivity of the Ames is high when using DMSO as a solvent (87-88%). Based on the analysis of these databases, the Ames assay conducted under OECD 471 guidelines is highly sensitive for detecting the carcinogenic hazards of NAs.

A Nitrite Excipient Database: A Useful Tool to Support N-Nitrosamine Risk Assessments for Drug Products

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.

Cancer Risk of Angiotensin II Receptor Blocker Valsartan: A Population-based Study

ABSTRACT

Nitrosamine contamination of generic valsartan was found in 2018. This study aimed to investigate whether long-term use of valsartan increases cancer risk. Patients prescribed valsartan or amlodipine (control group) from 1 January 1, 2003, to June 30, 2010, were identified using the Clinical Data Analysis and Reporting System of the Hong Kong Hospital Authority, a territory-wide database in Hong Kong. Patients previously diagnosed with cancer, prescribed both medications, taking the medication, or followed up for <1 year were excluded. Cancer incidence, adjusted for age, sex, and Charlson Comorbidity Index, was the primary outcome and was estimated using Poisson regression in R version 3.6.1. Among 5023 valsartan users and 3692 amlodipine users, 887 and 740 were diagnosed with cancers during median follow-up periods of 10.97 and 12.12 years, respectively. The adjusted incidence of cancer in valsartan and amlodipine users was 165.29 (95% confidence interval 154.76-175.53) and 180.12 (167.35-193.67) per 10,000 person-years, respectively. The cancer incidence rate ratio of valsartan relative to amlodipine was 0.94 (0.88-1.01). Adjusted incidence rate ratios of valsartan relative to amlodipine were significant for breast cancer (0.63, 0.46-0.86) only. Our findings do not suggest an increase in incidence of cancer with long-term valsartan use. The duration of follow-up of more than 10 years of the study provides the reassurance that an increase in cancer risk is unlikely. Further studies are needed to elucidate the long-term effect of valsartan use on the risk of specific types of cancer.

A substructure-based screening approach to uncover N-nitrosamines in drug substances

Drug substances are at risk of contamination with N-nitrosamines (NAs), well-known carcinogenic agents, during synthesis processes and/or long-term storage. Therefore, in this study, we developed an efficient data-based screening approach to systemically assess marketed products and investigated its scalability for benefiting both regulatory agencies and pharmaceutical industries. A substructure-based screening method employing DataWarrior, an open-source software, was established to evaluate the risks of NA impurities in drug substances. Eight NA substructures containing susceptible amino sources for N-nitrosation have been identified as screening targets: dimethylamine (DMA), diethylamine, isopropylethylamine, diisopropylamine, N-methyl-2-pyrrolidone, dibutylamine, methylphenylamine, and tetrazoles. Our method detected 192 drug substances with a theoretical possibility of NA impurity, 141 of which had not been reported previously. In addition, the DMA moiety was significantly dominant among the eight NA substructures. The results were validated using data from the literature, and a high detection sensitivity of 0.944 was demonstrated. Furthermore, our approach has the advantage of scalability, owing to which 31 additional drugs with suspected NA-contaminated substructures were identified using the substructures of 1-methyl-4-piperazine in rifampin and 1-cyclopentyl-4-piperazine in rifapentine. In conclusion, the reported substructure-based approach provides an effective and scalable method for the screening and investigation of NA impurities in various pharmaceuticals and might be used as an ancillary technique in the field of pharmaceutical quality control for risk assessments of potential NA impurities.

Salmonella typhimurium TA100 and TA1535 and E. coli WP2 uvrA are highly sensitive to detect the mutagenicity of short Alkyl-N-Nitrosamines in the Bacterial Reverse Mutation Test

Humans are exposed to low levels of N-nitrosamines via different sources. N-Nitrosamines have recently been detected as impurities in various marketed drugs and they are known mutagenic carcinogens belonging to the cohort of concern as referred to in the ICH M7 guideline. Despite their well-known mutagenic properties, there is ongoing discussion on the suitability of the bacterial reverse mutation assay and using induced rat liver S9 as the external source of metabolism to detect their mutagenic potential. Therefore, we have investigated the mutagenic potential of N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodipropylamine, and N-nitrosodibutylamine in vitro under various conditions. Our work showed that the bacterial reverse mutation assay applying plate incorporation or preincubation protocols and using Salmonella typhimurium strains TA100 and TA1535 and E. coli WP2 uvrA is suitable to predict the mutagenicity of n-nitrosamines in the presence of phenobarbital/β-naphthoflavone induced rat liver S9.

Inhibition of N-Nitrosamine Formation in Drug Products: A Model Study

Nitrosamines, in the absence of toxicological data, are regarded as potential mutagens and need to be controlled at nanogram levels in drug products. Recent high profile product withdrawals have increased regulatory scrutiny of nitrosamine formation assessments for marketed products and for new drug applications. Formation of nitrosamine in drug product is possible when nitrite and vulnerable amines are present. Nitrite is often present as an impurity in excipients at ppm levels, whereas vulnerable amines, if present, stem mainly from the drug substance or its major impurities. In the event a drug product were to contain a major source of vulnerable amines (such as a moiety in the drug substance), it would be desirable to have an inhibitor which could be added to the formulation to minimize nitrosamine formation.  This work demonstrates, for the first time, that the inhibition of nitrosamine formation in oral solid dosage forms is indeed feasible with suitable inhibitors. Five inhibitors investigated (ascorbic acid, sodium ascorbate, α-tocopherol, caffeic acid, and ferulic acid) showed >80% inhibition when spiked at ∼1 wt% level. This work has also shown the potential use of amino acids (glycine, lysine, histidine) as inhibitors of nitrosamine formation in solution.

Permitted daily exposure limits for noteworthy N-nitrosamines

A genotoxic carcinogen, N-nitrosodimethylamine (NDMA), was detected as a synthesis impurity in some valsartan drugs in 2018, and other N-nitrosamines, such as N-nitrosodiethylamine (NDEA), were later detected in other sartan products. N-nitrosamines are pro-mutagens that can react with DNA following metabolism to produce DNA adducts, such as O⁶ -alkyl-guanine. The adducts can result in DNA replication miscoding errors leading to GC>AT mutations and increased risk of genomic instability and carcinogenesis. Both NDMA and NDEA are known rodent carcinogens in male and female rats. The DNA repair enzyme, methylguanine DNA-methyltransferase can restore DNA integrity via the removal of alkyl groups from guanine in an error-free fashion and this can result in nonlinear dose responses and a point of departure or "practical threshold" for mutation at low doses of exposure. Following International recommendations (ICHM7; ICHQ3C and ICHQ3D), we calculated permissible daily exposures (PDE) for NDMA and NDEA using published rodent cancer bioassay and in vivo mutagenicity data to determine benchmark dose values and define points of departure and adjusted with appropriate uncertainty factors (UFs). PDEs for NDMA were 6.2 and 0.6 μg/person/day for cancer and mutation, respectively, and for NDEA, 2.2 and 0.04 μg/person/day. Both PDEs are higher than the acceptable daily intake values (96 ng for NDMA and 26.5 ng for NDEA) calculated by regulatory authorities using simple linear extrapolation from carcinogenicity data. These PDE calculations using a bench-mark approach provide a more robust assessment of exposure limits compared with simple linear extrapolations and can better inform risk to patients exposed to the contaminated sartans.

Use of less-than-lifetime (LTL) durational limits for nitrosamines: Case study of N-Nitrosodiethylamine (NDEA)

The ICH M7(R1) guideline describes a framework to assess the carcinogenic risk of mutagenic and carcinogenic pharmaceutical impurities following less-than-lifetime (LTL) exposures. This LTL framework is important as many pharmaceuticals are not administered for a patient's lifetime and as clinical trials typically involve LTL exposures. While there has been regulatory caution about applying LTL concepts to cohort of concern (COC) impurities such as N-nitrosamines, ICH M7 does not preclude this and indeed literature data suggests that the LTL framework will be protective of patient safety for N-nitrosamines. The goal was to investigate if applying the LTL framework in ICH M7 would control exposure to an acceptable excess cancer risk in humans. Using N-nitrosodiethylamine as a case study, empirical data correlating exposure duration (as a percentage of lifespan) and cancer incidence in rodent bioassays indicate that the LTL acceptable intake (AI) as derived using the ICH M7 framework would not exceed a negligible additional risk of cancer. Therefore, controlling N-nitrosamines to an LTL AI based on the ICH M7 framework is thus demonstrated to be protective for potential carcinogenic risk to patients over the exposure durations typical of clinical trials and many prescribed medicines.

A review on the protective effects of naringenin against natural and chemical toxic agents

Naringenin (NRG), as a flavanone from flavonoids family, is widely found in grapefruit, lemon tomato, and Citrus fruits. NRG has shown strong anti-inflammatory and antioxidant activities in body organs via mechanisms such as enhancement of glutathione S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activity, but reduction of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and malondialdehyde (MDA). Furthermore, NRG anti-apoptotic potential was indicated to be mediated by regulating B-cell lymphoma (Bcl-2), Bcl-2-associated X protein (Bax) and caspase3/9. Overall, these properties make NRG a highly fascinating compound with beneficial pharmacological effects. Based on the literature, NRG-induced protective effects against toxicities produced by natural toxins, pharmaceuticals, heavy metals, and environmental chemicals, were mainly mediated via suppression of lipid peroxidation, oxidative stress (through boosting the antioxidant arsenal), and inflammatory factors (e.g., TNF-α, interleukin [IL]-6, IL-10, and IL-12), and activation of PI3K/Akt and MAPK survival signaling pathways. Despite considerable body of evidence on protective properties of NRG against a variety of toxic compounds, more well-designed experimental studies and particularly, clinical trials are required before reaching a concrete conclusion. The present review discusses how NRG protects against the above-noted toxic compounds.

Critical Analysis of Drug Product Recalls due to Nitrosamine Impurities

A product recall is the outcome of a careful pharmacovigilance; and it is an integral part of drug regulation. Among various reasons for product recall, the detection of unacceptable levels of carcinogenic impurities is one of the most serious concerns. The genotoxic and carcinogenic potential of N-nitrosamines raises a serious safety concern, and in September 2020, the FDA issued guidance for the pharmaceutical industry regarding the control of nitrosamines in drug products. The FDA database shows that >1400 product lots have been recalled from the market due to the presence of carcinogenic N-nitrosamine impurities at levels beyond the acceptable intake limit of 26.5 ng/day. The drugs that were present in recalled products include valsartan, irbesartan, losartan, metformin, ranitidine, and nizatidine. This perspective provides a critical account of these product recalls with an emphasis on the source and mechanism for the formation of N-nitrosamines in these products.

Tolerability of risk: A commentary on the nitrosamine contamination issue

For decades, regulators have grappled with different approaches to address the issue of control of impurities. Safety-based limits, such as permissible daily exposure (PDE), acceptable intake (AI), threshold of toxicological concern (TTC) and less than lifetime limits (LTL) have all been used. For many years these safety-based limits have been recognized as virtually safe doses (VSDs). Recently, however, many regulatory agencies are seeking to impose limits for N-nitrosamine impurities, which are significantly below the VSD. This commentary will discuss the evolution of safety-based limits for impurities, provide an overview of the valsartan N-nitrosamine contamination issue and review the toxicology of N-nitrosamines. The outcome of a lessons-learned exercise on sartan medications undertaken by the European Medicines Agency (EMA) will also be discussed. The review will also highlight the many analytical challenges inherent with controlling impurities to ppb-based limits. The use of highly sensitive, low ppb limits, methods may lead to future issues of batch rejection, based on false positives. Regulators initially viewed the N-nitrosamine risk as being insufficient to prompt immediate product discontinuation and patients were specifically advised to continue using their affected medication. Patients were also informed that exposure to N-nitrosamines is extremely common via food and drinking water.

Processing-Structure-Performance Relationships of Microporous Metal-Organic Polymers for Size-Selective Separations

Small-molecule impurities, such as N-nitrosodimethylamine (NDMA), have infiltrated the generic drug industry, leading to recalls in commonly prescribed blood pressure and stomach drugs in over 43 countries since 2018 and directly affecting tens of millions of patients. One promising strategy to remove small-molecule impurities like NDMA from drug molecules is by size exclusion, in which the contaminant is removed by selective adsorption onto a (micro)porous material due to its smaller size. However, current solution-phase size-exclusion separations are primarily limited by the throughput-selectivity trade-off. Here, we report a bioinspired solution to conquer these critical challenges by leveraging the assembly of atomically precise building blocks into hierarchically porous structures. We introduce a bottom-up approach to form micropores, mesopores, and macroscopic superstructures simultaneously using functionalized oxozirconium clusters as building blocks. Further, we leverage recent advances in photopolymerization to design macroscopic flow structures to mitigate backpressure. Based on these multiscale design principles, we engineer simple, inexpensive devices that are able to separate NDMA from contaminated drugs. Beyond this urgent model system, we expect this design strategy to open up hitherto unexplored avenues of nanomaterial superstructure fabrication for a range of size-exclusion purification strategies.

Application of capillary electrophoresis-nano-electrospray ionization-mass spectrometry for the determination of N-nitrosodimethylamine in pharmaceuticals

After a presence of highly hepatotoxic and potentially carcinogenic N-nitrosodimethylamine was detected in certain lots of sartan, ranitidine, metformin, and other pharmaceuticals, local regulatory authorities issued recalls of suspected products, and concerns of the pharmacotherapy safety were widely discussed. Since then, testing of a representative sample of each produced lot of these pharmaceuticals is required as a part of quality control processes. Hence, an interface-free CE-nanoESI system coupled with MS detection was employed for the development of a simple and economical method for quantitative detection of this contaminant in the valsartan drug substances and finished formulations used as model matrices. In this arrangement, a fused-silica capillary was used as both a separation column and a nanoESI emitter providing high ionization efficiency and sensitivity. The optimized procedure was found to have sufficient selectivity, linearity, accuracy, and precision. The established LOD and LOQ values were 0.3 and 1.0 ng/mL, respectively. The practical applicability of the method was tested by analyses of commercially available Valsacor^® tablets. The results obtained prove that the developed procedure represents a promising alternative to currently available GC- and LC-based methods. Furthermore, after an adjustment of the separation conditions, the CE-nanoESI/MS system can be conceptually used for the determination of NDMA in other suspected pharmaceuticals.

N-Nitrosodimethylamine Contamination in the Metformin Finished Products

A GC–MS/MS method with EI ionization was developed and validated to detect and quantify N-nitrosodimethylamine (NDMA) and seven other nitrosamines in 105 samples of metformin tablets from 13 different manufactures. Good linearity for each compound was demonstrated over the calibration range of 0.5–9.5 ng/mL. The assay for all substances was accurate and precise. NDMA was not detected in the acquired active pharmaceutical ingredient (API); however, NDMA was detected in 64 (85.3%) and 22 (91.7%) of the finished product and prolonged finished product samples, respectively. European Medicines Agency recommends the maximum allowed limit of 0.032 ppm in the metformin products. Hence, 28 finished products and 7 pronged dosage products were found to exceed the acceptable limit of daily intake of NDMA contamination. The implications of our findings for the testing of pharmaceutical products are discussed.

An Analytic Investigation of the Drug Formulation-Based Recalls in the USA: See More Beyond the Literal

High numbers of drug recalls persist despite the tremendous time and effort invested by pharmaceutical organizations and regulatory bodies such as the Food and Drug Administration (FDA) to ensure the quality of safe and effective medicines for the patient. It is imperative to better understand the underlying risk factors of drug formulation-based recalls to best protect the patient from poor quality drugs. Increased knowledge of underlying factors of formulation risk can also help inform the future design and development of drugs. In this study, we used a text mining technique with Python to parse the data and examine drug recalls from the aspect of administration route, dosage form, release mechanism, market type, pharmacologic class, and excipients. Observational analysis of the recalls revealed both high- and low-risk factors for the formulation-based recalls. Higher risk, or an increased probability of a formulation-based recall, was associated with factors such as extended release mechanism, capsule dosage form, oral route of administration, and an increased number of excipients, while lower risk of formulation-based recalls was associated with other factors including the new drug application market type, immediate release mechanism, and solution dosage form. In addition, the factors did not work independently, and we observed interactions among variables. For example, the release mechanism modified the effect of market type, administration route, and dosage form. This study will help inform the future design of quality drug products by pharmaceutical organizations and assist risk-based oversight by regulatory organizations, such as FDA, to ensure patient safety.

Barriers and facilitators of exploiting the potential of value-added medicines

INTRODUCTION

Pharmaceutical research and development (R&D) is costly and only a minority of patients can access innovative medicines due to affordability constraints. Value-added medicines (VAMs) can offer potential benefits at significantly lower R&D costs.

AREAS COVERED

VAMs may address different health care needs and problems, including off-label use of medicines, poor patient adherence, problems related to polypharmacy, need for home and/or personalized health care services. However, several barriers prevent societies from maximizing the benefits of incremental innovation related to VAMs. Generic manufacturers have limited budget and experience to demonstrate the value of new VAMs. Current market exclusivity options do not efficiently exclude freeridership and do not guarantee a return on investment for VAM innovators. Value propositions of VAMs are limitedly consistent with current HTA frameworks, consequently, incremental innovation is not acknowledged, nor rewarded with differential pricing by payers. Moreover, VAMs are often perceived solely as generic medicines by prescribers.

EXPERT OPINION

Current practices may need to be reconsidered to exploit the full societal benefit of VAMs, including more efficient policies to guarantee market exclusivity for incremental innovation, acknowledgment of a fair price premium based on a specific value framework and the acceptance of low-cost evidence generation methods.

Chemical profiling of liposoluble liquid smokes obtained from Eucalyptus wood tar: confirmation of absence of polycyclic aromatic hydrocarbons

Liposoluble liquid smoke (LS) preparations are versatile food additives used worldwide. The objective of the present work was to characterise the chemical composition of four types of industrial liposoluble LS currently used as the basis for the production of commercial smoke flavourings. The LS was obtained by vacuum fractional distillation from a raw pyrolysis oil (raw LS) obtained primarily from eucalyptus wood tar. The raw LS and the four LS flavourings obtained therefrom were analysed by gas chromatography/mass spectrometry (GC/MS) to characterise the main groups of components. Additional analyses were carried out to evaluate the occurrence of PAHs (polycyclic aromatic hydrocarbons) in the samples, as the producer claimed that these samples are free of PAHs. The main chemical components characterised in the LS were organic acids, aldehydes, esters, furans, pyrans and phenols, with phenolic compounds being the major chemical group. For the four LS tested samples, no PAHs could be detected with the method employed, which could indicate that the industrial processing was able to effectively remove this harmful class of compounds, or at least decrease its concentrations to levels below the limits of detection of the method of analysis.

Industrial approaches and consideration of clinical relevance in setting impurity level specification for drug substances and drug products

The safety and efficacy of drug substances or products do not solely depend on its active(s). The quantity of impurities present in the product has a significant role in its safety profile. Pharmaceutical impurities are one of the primary reasons for the withdrawal of many approved products from the market. Therefore, the level of impurities in the pharmaceuticals needs to be controlled within a specified safe limit. Nowadays, setting impurity level specification remains a great challenge for pharmaceutical manufacturers. Regulatory guidelines recommend to control the impurity based on the concentration level criteria and provides limits of allowable impurities in pharmaceuticals. However, a single set of impurity limits cannot work for all the drug substances. There are numerous reasons which demand to set the impurity level specification based on safety dominated critical quality attribute principle. In this review, we have discussed the need for the consideration of both concentration based and patient safety-related approaches for setting the impurity level specification. To achieve this goal, it is required to identify the safety limits of the impurities during clinical development and provide a specification for the finished pharmaceutical products before entering the market. However, tremendous challenges faced by pharmaceutical companies to have an appropriate balance amongst the critical factors like safety, efficacy, analytical variability, process knowledge and regulatory requirement. Finally, the specification for API and finished drug product should be established considering both quality and patient safety. Considering all such factors, we have included a systematic and scientific approach that can guide to establish the safe and flexible impurity limit specification for pharmaceuticals.