A rationale for determining, testing, and controlling specific impurities in pharmaceuticals that possess potential for genotoxicity

Pharmacological reduction of lipid hydroperoxides as a potential modulator of sarcopenia

We previously reported that elevated expression of phospholipid hydroperoxide glutathione peroxidase 4, an enzyme that regulates membrane lipid hydroperoxides, can mitigate sarcopenia in mice. However, it is still unknown whether a pharmacological intervention designed to modulate lipid hydroperoxides might be an effective strategy to reduce sarcopenia in aged mice. Here we asked whether a newly developed compound, CMD-35647 (CMD), can reduce muscle atrophy induced by sciatic nerve transection. We treated mice daily with vehicle or CMD (15 mg/kg, i.p. injection) starting 1 day prior to denervation. CMD treatment reduced hydroperoxide generation and blunted muscle atrophy by over 17% in denervated muscle. To test whether CMD can reduce ageing-induced muscle atrophy and weakness, we treated mice with either vehicle or CMD (15 mg/kg, i.p. injection) 3 days per week for 8 months, starting at 18 months of age until 26 months of age. We measured muscle mass, functional status of neuromuscular junctions, muscle contractile function and mitochondrial function in control and CMD-treated 26-month-old female mice. Treatment with CMD conferred protection against muscle atrophy in both tibialis anterior and extensor digitorum longus that was associated with maintenance of fibre size of MHC 2b and 2x fibres. Mitochondrial respiration was also protected in CMD-treated mice. We also found that muscle force generation was protected with CMD treatment despite denervation in ∼25% of the muscle fibres. Overall, this study shows that pharmacological interventions designed to reduce lipid hydroperoxides might be effective for preventing sarcopenia. KEY POINTS: Sarcopenia in aged mice is associated with muscle loss, contractile dysfunction, denervation, and reduced mitochondrial respiration. CMD-35647 is a pharmocological compound that can neutralize lipid hydroperoxides. 8 month treatment of CMD-35647 mitigated muscle atrophy in tibialis anterior and extensor digitorum longus. 8 month treatment of CMD-35647 improved muscle function in aged mice independent of the neuromuscular junction. Aged mice treated with CMD-35647 had greater respiration in red gastrocnemius muscle when compared to vehicle treated mice.

Critical comparison of BMD and TD50 methods for the calculation of acceptable intakes for N-nitroso compounds

The tumorigenic dose 50 (TD50) is a widely used measure of carcinogenic potency which has historically been used to determine acceptable intake limits for carcinogenic compounds. Although broadly used, the TD50 model was not designed to account for important biological factors such as DNA repair and cell compensatory mechanisms, changes in absorption, etc., leading to the development of benchmark dose (BMD) approaches, which use more flexible dose-response models that are better able to account for these processes. Using a nitrosamine dataset as a case study, we compare the impact of moving to a BMD-based limit as opposed to a TD50-based limit. Although there are differences in individual potency estimates between the two approaches for some compounds, we show that the key metrics such as the 5th percentile of the respective potency distributions, used when calculating class-specific default acceptable intakes, are not greatly affected. Furthermore, potency estimates for nitrosamine compounds relevant to read-across do not vary by more than a factor of 3, which is little in the context of the inherent variability in a biological response, in an overall landscape wherein potencies can vary by four orders of magnitude. This suggests a move to BMD-based limits is achievable without significant disruption to existing limits while utilising a more robust methodology.

Oxidative stress-induced degradation of Brinzolamide: Isolation and in-depth characterization of unique hydroxylamine and oxime degradation products

Since the safety and efficacy of therapeutic products are strongly related to their stability and purity, impurities including the unavoidable degradation products may affect the pharmacological effect. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines Q3A requires the identification of process impurities and as well as degradation products in any drug substance to assess the inherent stability of the drug. The present work involves an ICH-guided degradation study for the Brinzolamide (BRZ), a topical ophthalmic drug which is generally used to lower the intraocular pressure (IOP) during glaucoma. Under oxidative stress at room temperature for 20 h, four degradation products (namely BRZ-Pk1, BRZ-PK2, BRZ-Pk3, and BRZ-Pk4) are isolated using advanced chromatographic techniques. Upon confirming the masses of the compounds using High-resolution mass spectrometry (HRMS), functional groups are identified with the help of Fourier-transform infrared spectroscopy (FT-IR). Extensive 1-dimensional (1D) and 2-dimensional (2D) Nuclear Magnetic Resonance spectroscopic (NMR) experiments especially 1D nOe, 1H-13C-HSQC and 1H-13C-HMBC unequivocally confirm the structures. Among the four compounds analyzed, three (BRZ-Pk1, BRZ-Pk2, and BRZ-Pk4) are novel, while BRZ-Pk3 was previously reported solely with mass spectrometric data. Nitrogen-based 2D NMR experiments are crucial for determining the oxidation state of hydroxylamine and oxime products within the molecules, and 1D nOe measurements help confirming E/Z isomerism (geometrical isomerism) for BRZ-Pk2 and BRZ-Pk4. All the proposed structures are justified with appropriate analytical data. The proposed mechanisms are expected to help in identifying the possible degradation pathways for similar pharmaceutical candidates.

Determination of residual alkyl iodides and alkyl bromides as their corresponding alkyl chlorides in drug substances by headspace GC-FID

Primary and secondary alkyl iodides and primary alkyl bromides were quickly and conveniently converted into their corresponding alkyl chlorides via SN2 halide-halide substitution. The resultant alkyl chlorides simultaneously demonstrated increased volatility and stability paired with standard headspace GC-FID methodology. The derivatization was performed on both standard and sample alike and occurred during the headspace oven equilibration phase, eliminating the extra reaction step traditionally performed during many derivatization analyses. Reaction times, temperatures, and completeness of conversion were studied as well as response from common headspace solvents and application of various chloride sources. Recovery of iodomethane from four challenging substrates was studied from the trace level to approximately 1000 ppm. Recovery ranged 94-110 % from verapamil hydrochloride (2.5-1007 ppm), 95-102 % from methylnaltrexone bromide (26-1054 ppm), and 92-106 % from (S)-laudanosine (49-942 ppm). Using hydrogen chloride as the chloride source, a method for determination of residual iodomethane in (S)-N-methyl-laudanosine iodide was validated over a 0.5-24.9 μg/mL range with a 0.1 μg/mL detection limit, 91-103 % accuracy, and 3.2 % relative standard deviation.

A novel liquid chromatography with quadrupole time-of-flight-tandem mass spectroscopy method for ultra-trace level identification and quantification of the genotoxic impurity 2,6-diamino-5-nitropyrimidin-4(3H)-one in valganciclovir hydrochloride

In the present study, the main objective is to develop an analytical method for ultra-trace level measurement of 2,6-diamino-5-nitropyrimidin-4(3H)-one (DMNP) in valganciclovir hydrochloride (VAL) using liquid chromatography-quadrupole time-of-flight-tandem mass spectroscopy (LC-QTOF-MS/MS). In the early stages of guanine synthesis, DMNP is formed, and guanine is known to be the key starting material for the synthesis of VAL. Taking into consideration DMNP potential genotoxicity, this analytical method has been developed. This method is time saving and suitable for confirming the masses of parent and fragment ions by MS and MS/MS further fragmentation. An isocratic program and Acquity UPLC HSS cyano column (100 × 2.1 mm × 1.8 μm) were used to achieve optimal separation between VAL and the DMNP impurity. A 0.1% ammonia solution in Milli-Q water was used as mobile phase A, and methanol was used as mobile phase B in the ratio 90:10 v/v in isocratic mode. In accordance with the International Conference on Harmonization's requirements, the developed method was validated. The detection and quantification levels were found to be 0.028 and 0.083 ppm respectively. The DMNP impurity is linear from 0.083 to 1.245 ppm levels with correlation coefficient (R2 ) of 0.9960. The recoveries were found to be 97.0-107.9%.

Genotoxic Impurities in Critical Analysis of Product Development: Recent Advancements, Patents, and Current Challenges

The current review intends to regulate and accurately evaluate genotoxic contaminants in drug substance and drug product method and formulation process development, validation, and degradation pathways. The Quality by Design (QbD) principles can be applied to the systematic evaluation and control of impurities enabled by the development of modern analytical techniques, including the performance of risk assessment, the screening of Critical Process Parameters (CPPs), and the identification of the most influential variables in the optimization of the evaluation and control methods. Current difficulties in removing genotoxic contaminants and the procedures for doing so have been outlined in this review, along with the steps necessary to acquire optimum techniques and the most acceptable formulations. In addition to this, division, characterization, assessment, quantification, and formation of genotoxic impurities sources and control strategy for genotoxic impurities, handling of nitrosamine assay content of drug products in different industrial methodologies and their chemometric prospects and associated recent patents are also explored.

A sensitive ultra-performance liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of assay and trace-level genotoxic tosylate analogs (methyl and ethyl) in empagliflozin and its tablet dosage forms

This study performed the simultaneous quantification of assay and two alkyl sulfonate (tosylate) analogs of empagliflozin (EGZ), specifically methyl 4-methyl benzene sulfonate (MMBS) and ethyl 4-methyl benzene sulfonate (EMBS) in EGZ, and its finished dosage form using an accurate and sensitive ultra-performance liquid chromatography-mass spectrometry method. The separation was achieved on a Waters Acquity BEH Shield RP18 (100 × 2.1 mm, 1.7 μm) column in gradient elution mode with 0.1% formic acid and acetonitrile as the mobile phases and a flow rate of 0.5 mL/min. For simultaneous quantification, the multiple reaction monitoring technique was utilized. The procedure was successfully validated in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. The peak areas of both impurities, along with their concentrations, exhibited a good relationship with Pearson's correlation coefficient (R), which was >0.999 in the range of 0.3-6 ppm with an EGZ concentration of 2 mg/mL. The percentage recoveries from the limit of quantitation (LOQ) to 200% to the specification level were in the range of 94.82%-102.92%, whereas the percentage relative standard deviation (%RSD) was <2. Therefore, this method is rapid and accurate to quantify MMBS, EMBS, and EGZ assay simultaneously from the marketed tablet dosage forms of EGZ for commercial release and stability sample testing.

Datasets Construction and Development of QSAR Models for Predicting Micronucleus In Vitro and In Vivo Assay Outcomes

In silico (quantitative) structure-activity relationship modeling is an approach that provides a fast and cost-effective alternative to assess the genotoxic potential of chemicals. However, one of the limiting factors for model development is the availability of consolidated experimental datasets. In the present study, we collected experimental data on micronuclei in vitro and in vivo, utilizing databases and conducting a PubMed search, aided by text mining using the BioBERT large language model. Chemotype enrichment analysis on the updated datasets was performed to identify enriched substructures. Additionally, chemotypes common for both endpoints were found. Five machine learning models in combination with molecular descriptors, twelve fingerprints and two data balancing techniques were applied to construct individual models. The best-performing individual models were selected for the ensemble construction. The curated final dataset consists of 981 chemicals for micronuclei in vitro and 1309 for mouse micronuclei in vivo, respectively. Out of 18 chemotypes enriched in micronuclei in vitro, only 7 were found to be relevant for in vivo prediction. The ensemble model exhibited high accuracy and sensitivity when applied to an external test set of in vitro data. A good balanced predictive performance was also achieved for the micronucleus in vivo endpoint.

Mutagenic impurities in pharmaceuticals: A critical assessment of the cohort of concern with a focus on N-nitrosamines

The TTC (Threshold of Toxicological Concern; set at 1.5 μg/day for pharmaceuticals) defines an acceptable patient intake for any unstudied chemical posing a negligible risk of carcinogenicity or other toxic effects. A group of high potency mutagenic carcinogens, defined solely by the presence of particular structural alerts, are referred to as the "cohort of concern" (CoC); aflatoxin-like-, N-nitroso-, and alkyl-azoxy compounds are considered to pose a significant carcinogenic risk at intakes below the TTC. Kroes et al.2004, derived values for the TTC and CoC in the context of food components, employing a non-transparent dataset never placed in the public domain. Using a reconstructed all-carcinogen dataset from relevant publications, it is now clear that there are exceptions for all three CoC structural classes. N-Nitrosamines represent 62% of the N-nitroso class in the reconstructed dataset. Employing a contemporary dataset, 20% are negative in rodent carcinogenicity bioassays with less than 50% of N-nitrosamines estimated to fall into the highest risk category. It is recommended that CoC nitrosamines are identified by compound-specific data rather than structural alerts. Thus, it should be possible to distinguish CoC from non-CoC N-nitrosamines in the context of mutagenic impurities described in ICH M7 (R1).

In silico toxicity assessment and trace level quantification of two genotoxic impurities in silodosin using capillary gas chromatography

A capillary gas chromatographic method using flame ionization detection was developed and validated for the trace quantification of 2-bromoethanol (2-BE) and 2-bromoethylmethanesulfonate (2-BEM) in silodosin, used in the treatment of benign prostatic hyperplasia. Chromatographic separation was performed in spilt mode using nitrogen as carrier gas on a column containing crosslinked polyethylene glycol (30 m × 0.32 mm, 0.25 µm) stationary phase modified with nitroterephthalic acid. A simple matrix precipitation strategy was implemented to eliminate the sample overload and the matrix interference problems. The developed method was linear and accurate in the concentration range of 24–3000 ppm for 2-BE and 24–300 ppm for 2-BEM with r2 ˃ 0.999 and percent recoveries greater than 90% for both the analytes. The developed method was precise for both the analytes with RSD(%) of not more than 4.5%. In silico genotoxicity and carcinogenicity potential of 2-BEM were assessed using ICH M7 principles. The developed method can be applied in the quality control laboratories of pharmaceutical industries for trace level quantification of 2-BE and 2-BEM in silodosin.

Continuous Extraction of 2-Chloroethyl isocyanate for 1-(2-chloroethyl)-3-cyclohexylurea Purification

This study details the development of simulation-aided design, development, and successful operation of a continuous liquid-liquid extraction platform made with 1.5 mm tubing for the extraction of 2-chloroethyl isocyanate, an important reagent in the synthesis of cancer drugs. Preliminary solvent screening was carried out with partition coefficient calculations to determine solvents of interest. Next, batch and flow extraction experiments of 2-chloroethyl isocyanate in 2-methyl tetrahydrofuran and water were conducted to estimate extraction parameters. Following parameter estimation, experimental and model values for KLa were determined in the range of 1.13×10-3 to 36.0×10-3 s-1. Simulations of the extraction of 2-chloroethyl isocyanate were found to agree with experimental data resulting in a maximum efficiency of 77% and percent extraction of 69% for the continuous platform. Finally, model selection and discrimination was implemented for design space generation with experimental and model determined KLa values to guide lab-scale operation.

A sensitive LC-MS/MS method for the determination of potential genotoxic impurities in Cinnarizine

A highly sensitive LC-MS/MS method for the trace level determination of genotoxic impurities, Cinnamyl chloride and Benzhydryl chloride, in Cinnarizine drug substance was developed and validated. Chromatographic separation was successfully achieved on Atlantis d C18 column with dimensions 150× 4.6mm and particle size: 5μm. 0.1% Trifluoroacetic acid in water and 100% acetonitrile was used as mobile phases with gradient mode of elution at 1.0mL/min flow rate. Mass spectroscopic detection was carried out with selective ion monitoring (SIM) technique in positive mode at m/z 117 and 167 for Cinnamyl chloride and Benzhydryl chloride respectively. Developed method was proven to be selective, sensitive, and precise for the quantification of potential genotoxic impurities in Cinnarizine by validating as per the regulatory guidelines. The LOD and LOQ values observed for Cinnamyl chloride were 0.49 and 1.47ppm and for Benzhydryl chloride 0.55 and 1.67ppm respectively. Precision of the method at LOQ level was shown with good % RSD of 4.21. Method was proven linear from LOQ to 150% level with a correlation of 0.996 and accurate with a range of recovery from 86.4 to 100.8%. This highly sensitive method can be used to control both the genotoxic impurities in Cinnarizine drug substance by LC-MS/MS.

Evaluating the utility of the Threshold of Toxicological Concern (TTC) and its exclusions in the biocompatibility assessment of extractable chemical substances from medical devices

The Threshold of Toxicological Concern (TTC) is a pragmatic approach used to establish safe thresholds below which there can be no appreciable risk to human health. Here, a large inventory of ~45,000 substances (referred to as the LRI dataset) was profiled through the Kroes TTC decision module within Toxtree v3.1 to assign substances into their respective TTC categories. Four thousand and two substances were found to be not applicable for the TTC approach. However, closer examination of these substances uncovered several implementation issues: substances represented in their salt forms were automatically assigned as not appropriate for TTC when many of these contained essential metals as counter ions which would render them TTC applicable. High Potency Carcinogens and dioxin-like substances were not fully captured based on the rules currently implemented in the software. Phosphorus containing substances were considered exclusions when many of them would be appropriate for TTC. Refinements were proposed to address the limitations in the current software implementation. A second component of the study explored a set of substances representative of those released from medical devices and compared them to the LRI dataset as well as other toxicity datasets to investigate their structural similarity. A third component of the study sought to extend the exclusion rules to address application to substances released from medical devices that lack toxicity data. The refined rules were then applied to this dataset and the TTC assignments were compared. This case study demonstrated the importance of evaluating the software implementation of an established TTC workflow, identified certain limitations and explored potential refinements when applying these concepts to medical devices.

Analytical Method Development for 19 Alkyl Halides as Potential Genotoxic Impurities by Analytical Quality by Design

Major issues in the pharmaceutical industry involve efficient risk management and control strategies of potential genotoxic impurities (PGIs). As a result, the development of an appropriate method to control these impurities is required. An optimally sensitive and simultaneous analytical method using gas chromatography with a mass spectrometry detector (GC–MS) was developed for 19 alkyl halides determined to be PGIs. These 19 alkyl halides were selected from 144 alkyl halides through an in silico study utilizing quantitative structure–activity relationship (Q-SAR) approaches via expert knowledge rule-based software and statistical-based software. The analytical quality by design (QbD) approach was adopted for the development of a sensitive and robust analytical method for PGIs. A limited number of literature studies have reviewed the analytical QbD approach in the PGI method development using GC–MS as the analytical instrument. A GC equipped with a single quadrupole mass spectrometry detector (MSD) and VF-624 ms capillary column was used. The developed method was validated in terms of specificity, the limit of detection, quantitation, linearity, accuracy, and precision, according to the ICH Q2 guideline.

Comparative study of performances of UHPLC-MS/MS and HPLC/UV methods for analysis of ziprasidone and its main impurities

Ziprasidone is the second generation antipsychotic drug with unique multipotent G-protein-coupled (GPCR) receptor binding profile. Since ziprasidone is a highly lipophilic and unstable compound, development of efficient method for a concurrent assay of ziprasidone and its main impurities was a very challenging task.

The UHPLC-MS/MS method that we developed for simultaneous determination of ziprasidone and its main impurities (BITP, Chloroethyl-chloroindolinone, Zip-oxide, Zip-dimer, and Zip-BIT) was compared with some other related HPLC-UV methods of our own and other authorship. An increase of the mobile phase pH value from 2.5 to 4.7 units in the examined analytical methods influenced elution order of the investigated compounds. It was found out that the UHPLC-MS/MS method is more selective and sensitive than the earlier developed HPLC-UV method. Similar to our earlier HPLC-UV method, the UHPLC-MS/MS method is linear with a correlation coefficient (r) above 0.99 for all the analysed compounds, but with a negligibly lower precision and accuracy. Finally, with shorter analysis time, smaller column size and reduction of solvent consumption, UHPLC-MS/MS is assumed as a greener method than HPLC-UV for the ziprasidone purity assay.

After transfer of the UHPLC-MS/MS method to the UHPLC-DAD system, suitability of the UHPLC-DAD method for routine control of ziprasidone and its main impurities is examined and confirmed based on the retained good selectivity, resolution and short analysis time.

Differentiation of Protonated Sulfonate Esters from Isomeric Sulfite Esters and Sulfones by Gas-Phase Ion-Molecule Reactions Followed by Diagnostic Collision-Activated Dissociation in Tandem Mass Spectrometry Experiments

Sulfonate esters, a class of potentially mutagenic drug impurities, are strictly regulated in pharmaceuticals. On the other hand, sulfite esters and sulfones, analogs of sulfonate esters, have limited safety concerns. However, previously developed analytical methods for sulfonate ester identification cannot be used to differentiate sulfonate esters from the isomeric sulfite esters and sulfones. A tandem mass spectrometric method is introduced here for the differentiation of these compounds. Diisopropoxymethylborane (DIMB) reacts with protonated sulfonate esters, sulfite esters, and sulfones (and many other compounds) in the gas phase to form the product ion [M + H + DIMB - CH₃CH(OH)CH₃]⁺. Upon collision-activated dissociation (CAD), these product ions generate diagnostic fragment ions that enable the differentiation of sulfonate esters, sulfite esters, and sulfones from each other. For example, SO₂ elimination enabled the unambiguous identification of sulfite esters. On the other hand, elimination of CH₃B═O followed by elimination of (CH₃)₂C═O was only observed for sulfonate esters. Neither type of diagnostic fragment ions was detected for the products of sulfones. However, the product ions formed for sulfones with an additional hydroxyl substituent underwent the elimination of another CH₃CH(OH)CH₃ molecule, which enabled their identification. Finally, ion-molecule reactions of DIMB with various other functionalities were also examined. Some of them yielded the product ions [M + H + DIMB - CH₃CH(OH)CH₃]⁺ but none of these product ions underwent the diagnostic CAD reactions discussed above. Quantum chemical calculations were employed to explore the mechanisms of the reactions. The limits of detection for the diagnostic ion-molecule reaction product ions in high-performance liquid chromatography (HPLC)/mass spectrometry (MS²) experiments were found to range from 0.075 to 1.25 nmol.

Trace Level Quantification of 4-Methyl-1-nitrosopiperazin in Rifampicin Capsules by LC-MS/MS

Rifampicin is a first-line anti-tuberculosis drug. However, in August 2020, the presence of 1-methyl-4-nitrosopiperazine (MNP), a nitrosamine impurity, was detected by the United Stated Food and Drug Administration (US FDA) in rifampicin capsules. Consequently, the development of efficient methods for the detection of MNP is an important objective. In this study, the MNP present in rifampicin capsules was detected using LC-MS/MS. A total of 27 batches from nine manufacturers in the Chinese market were tested, with MNP (0.33–2.36 ppm) being detected in all samples at levels exceeding the maximum acceptable intake limit of 0.16 ppm initially set by the FDA. However, after considering the associated benefits and risks, the FDA-approved limit was revised to 5 ppm; hence, all the samples examined herein exhibited MNP levels well below the required limit. Furthermore, the results of forced degradation experiments suggest that MNP is formed by the thermal degradation of rifampicin.

Recent Progresses in Analytical Perspectives of Degradation Studies and Impurity Profiling in Pharmaceutical Developments: An Updated Review

Forced degradation studies have been used to simplify analytical methodology development and achieve a deeper knowledge about the inherent stability of active pharmaceutical ingredients (API) and drug products. This provides insight into degradation species and pathways. Identification of impurities in pharmaceutical products is closely related to the selection of the most appropriate analytical methods like HPLC-UV, LC-MS/MS, LC-NMR, GC-MS, and capillary electrophoresis. Herein, recent trends in analytical perspectives during 2018-April 14, 2021, are discussed based on forced and impurity degradation profiling of pharmaceuticals. Literature review showed that several methods have been used for experimental design and analysis conditions such as matrix type, column type, mobile phase, elution modes, detection wavelengths, and therapeutic category. Thus, since these factors influence the separation and identification of the impurities and degradation products, we attempted to perform a statistical analysis for the developed methods according to the abovementioned factors.

Development and Validation of Liquid Chromatography - Tandem Mass Spectrometry Method for the estimation of Potential Genotoxic Impurity 2-(2-Chloroethoxy)ethanol in Hydroxyzine

2-(2-Chloroethoxy)ethanol (CEE) belongs to the so-called cohort of concerns which were classified as a highly potent mutagenic carcinogen by the World Health Organization. CEE is widely used in the synthesis of essential anti-histamine drug hydroxyzine. Besides, it is used as primary solvent in the dyes, nitrocellulose, paints, inks and resins. Owing to its potential genotoxicity, an efficient liquid chromatography-tandem mass spectrometry method was developed for the quantitative estimation of CEE traces in an active pharmaceutical ingredient and in tablet dosage forms of hydroxyzine-free base. The chromatographic separation was achieved on C₁₈ column using a gradient elution mode with a binary solvent system (ammonium formate and methanol). Mass detection was performed for the CEE using a positive mode with selected ion monitoring technique at m/z value of [M+NH₄ ]⁺ . The developed method was validated as per the ICH guideline, the quantitation limit, linearity and recoveries were found to be 0.56 ppm, 0.56 ~ 7.49 ppm (r² > 0.9985) and 93.6 ~ 99.3%, respectively. The proposed method was highly compatible and was worked effectively to estimate the CEE traces in different stages of drug synthesis and in tablet dosage forms of hydroxyzine for the routine and stability testing.

Increasing the Value of Data Within a Large Pharmaceutical Company Through In Silico Models

The present contribution describes how in silico models and methods are applied at different stages of the drug discovery process in the pharmaceutical industry. A description of the most relevant computational methods and tools is given along with an evaluation of their performance in the assessment of potential genotoxic impurities and the prediction of off-target in vitro pharmacology. The challenges of predicting the outcome of highly complex in vivo studies are discussed followed by considerations on how novel ways to manage, store, exchange, and analyze data may advance knowledge and facilitate modeling efforts. In this context, the current status of broad data sharing initiatives, namely, eTOX and eTransafe, will be described along with related projects that could significantly reduce the use of animals in drug discovery in the future.

Liquid Chromatography-Mass Spectrometric Methods for Trace Quantification of Potential Genotoxic Impurities in Ivacaftor and Lumacaftor

OBJECTIVE

The objective of the current study was to develop and validate the sensitive LC-MS methods for trace analysis of genotoxic impurities in Ivacaftor and Lumacaftor. The first method is for the trace analysis of 2,4-di-tert-butyl-5-nitrophenol in ivacaftor and the second method is for the trace analysis of 1-(2,2-difluoro-1,3-benzodioxol-5yl)-cyclopropane carboxylic acid and 3-carboxyphenyl boronic acid in lumacaftor.

MATERIALS AND METHODS

High pure analytical grade solvents and reagents were used for this study. The chromatographic separation was performed on Luna C18 (250 × 4.6 mm, 5.0 µm) at a column temperature of 25 °C using eluent consisting of acetonitrile and 0.1% v/v formic acid in water in a gradient elution mode. The eluent was run at a flow of 1.0 mL/min and injection volume of 20 µL.

RESULTS

The linearity, precision and accuracy of the developed methods was validated over the concentration range of 0.35 - 15.0 ppm for 2,4-di-tert-butyl-5-nitrophenol, 0.30 - 15.0 ppm for 1-(2,2-difluoro-1,3-benzodioxol-5yl)-cyclopropane carboxylic acid and 0.23 - 15.0 ppm for 3-carboxyphenyl boronic acid. In both methods, interference was not observed at the retention time of analyte peaks. All the analytes were found to be stable in solution for a period of 48 h.

CONCLUSION

The proposed methods are reliable, sensitive, precise, accurate, and robust for the trace level quantification of genotoxic impurities in Ivacaftor and Lumacaftor. These methods can be successfully implemented in the quality control lab for routine analysis.

Liquid chromatography-tandem mass spectrometric method for trace quantification of ethyl methanesulfonate: a genotoxic impurity in dapoxetine hydrochloride

Background

Dapoxetine hydrochloride is a selective serotonin reuptake inhibitor drug for treating premature ejaculation. This study was designed to develop and validate a sensitive and selective LC–MS/MS method for trace analysis of genotoxic impurity ethyl methanesulfonate in Dapoxetine hydrochloride.

Results

Chromatographic separation was achieved on the Shodex RSpak DS-413 column, 150 × 4.6 mm, 3.0 µm using eluent containing a equal volumes of acetonitrile and 0.1% v/v formic acid in water was used in the isocratic elution mode at a pump flow of 1.0 mL/min. No interference was observed at the retention time of ethyl methanesulfonate, indicating that the developed method is specific and selective for trace level quantification.The developed method was found to be linear in the concentration range of 1–50 ppm with coefficient of regression of 0.9997. Detection limit and quantification limit were determined to be 0.6 ppm and 1.0 ppm respectively. Acceptable RSD values (< 10.0%) and recovery results (> 90%) obtained from the accuracy and precison experiments indicate that the developed method is precise and accurate in the concentration range of 1–50 ppm. Ethyl methanesulfonate solutions were stable for two days when stored at room and refrigerated temperatures.

Conclusion

The developed method has the ability to quantify ethyl methanesulfonate in dapoxetine hydrochloride. Thus, the anticipated method has high probability to adopt in the quality testing laboratories of pharmaceutical industry.

HPLC-MS Analysis of Four Potential Genotoxic Impurities in Alogliptin Pharmaceutical Materials

BACKGROUND

Pyridine, 3-aminopyridine, 4-dimethylaminopyridine, and N, N-dimethylaniline are reactive bases that may be used in preparing of alogliptin (ALO) pharmaceutical ingredient. They are considered as potentially genotoxic impurities since they contain electrophilic functional groups. Therefore, they should be monitored at the allowed limits in ALO.

OBJECTIVE

The aim of this study was to develop a novel liquid chromatography mass spectrometry (LC-MS) method to estimate quantities of pyridine, 3-aminopyridine, 4-dimethylaminopyridine, and N, N-dimethylaniline impurities in ALO drug material.

METHODS

The separation was performed on KROMASIL CN (250 mm × 3.9 mm, 3.5 µm) column in reversed phase mode. The mobile phase was a mixture of water-methanol (55:45, v/v) containing 2.5 mM ammonium acetate and 0.1% formic acid.The mass spectrometer was used to detect the amount of impurities with selected ionization monitoring mode at m/z = 80, 95, 122, and 123 for pyridine, 3-aminopyridine, N, N-dimethylaniline and 4-dimethylaminopyridine, respectively. Flow rate of the method was 0.5 mL/min.

RESULTS

Sensitivity of the method was excellent at levels very less than allowed limits. The method had excellent linearity in the concentration ranges of QL-150% of allowed limits and coefficients of determination were above 0.9990. The recovery ratios were in the range of 93.56-110.28%.

CONCLUSIONS

Results showed good linearity, precision, accuracy, sensitivity, selectivity, robustness, and solution stability. The studied method was applied to test two samples of raw materials and one sample of tablets.

HIGHLIGHTS

The method discussed here could be very useful for controlling of potentially genotoxic impurities levels in ALO during its synthesis and for testing ALO raw materials as quality control tests before using them in preparing of pharmaceutical products.

Challenges in setting Permitted Daily Exposure (PDE) Limits for pharmaceuticals: A review

BACKGROUND

When more than one drug is manufactured at a shared facility or equipment in pharmaceutical manufacturing, the potential carry-over of the retained residue of existing drug product on product contact parts of the equipment to the next product can be a source of cross contamination. Permitted daily exposure (PDE) is derived based on the complete nonclinical and clinical data available and is a dose that is unlikely to cause adverse effects if an individual is exposed, by any route, at or below this dose every day over a lifetime.

OBJECTIVE

The objective was to present a comprehensive review of available scientific knowledge for derivation of PDE.

METHODS

PubMed and ScienceDirect databases were searched using keywords "PDE" and "pharmaceuticals" and all the relevant literature up to March 2021 was reviewed. We have also calculated PDEs for Tobramycin (CAS No. 32986-56-4) and Acetyl Salicylic Acid (ASA, CAS No. 50-78-2).

RESULTS

This research will be useful for scientists working in the PDE domain. The given examples emphasize the importance of use of human data in calculating PDE.

CONCLUSION

The duty of the risk assessor entrusted with setting PDEs is to derive a data driven, scientifically justified value that is safe for patients, while avoiding unjustified conservativeness that puts unnecessary burden on manufacturing.

Assessing the impact of expert knowledge on ICH M7 (Q)SAR predictions. Is expert review still needed?

The ICH M7 (R1) guideline recommends the use of complementary (Q)SAR models to assess the mutagenic potential of drug impurities as a state-of-the-art, high-throughput alternative to empirical testing. Additionally, it includes a provision for the application of expert knowledge to increase prediction confidence and resolve conflicting calls. Expert knowledge, which considers structural analogs and mechanisms of activity, has been valuable when models return an indeterminate (equivocal) result or no prediction (out-of-domain). A retrospective analysis of 1002 impurities evaluated in drug regulatory applications between April 2017 and March 2019 assessed the impact of expert review on (Q)SAR predictions. Expert knowledge overturned the default predictions for 26% of the impurities and resolved 91% of equivocal predictions and 75% of out-of-domain calls. Of the 261 overturned default predictions, 15% were upgraded to equivocal or positive and 79% were downgraded to equivocal or negative. Chemical classes with the most overturns were primary aromatic amines (46%), aldehydes (45%), Michael-reactive acceptors (37%), and non-primary alkyl halides (33%). Additionally, low confidence predictions were the most often overturned. Collectively, the results suggest that expert knowledge continues to play an important role in an ICH M7 (Q)SAR prediction workflow and triaging predictions based on chemical class and probability can improve (Q)SAR review efficiency.

Automatic Identification of Lansoprazole Degradants under Stress Conditions by LC-HRMS with MassChemSite and WebChembase

Stress testing is one of the most important parts of the drug development process, helping to foresee stability problems and to identify degradation products. One of the processes involving stress testing is represented by forced degradation studies, which can predict the impact of certain conditions of pH, moisture, heat, or other negative effects due to transportation or packaging issues on drug potency and purity, ensuring patient safety. Regulatory agencies have been working on a standardization of laboratory procedures since the past two decades. One of the results of those years of intensive research is the International Conference on Harmonization (ICH) guidelines, which clearly define which forced degradation studies should be performed on new drugs, which become a routine work in pharmaceutical laboratories. Since used techniques based on high-performance liquid chromatography coupled with high-resolution mass spectrometry have been developed years ago and are now mastered by pharmaceutical scientists, automation of data analysis, and thus data processing, is becoming a hot topic nowadays. In this work, we present MassChemSite and WebChembase as a tandem to automatize the routine analysis studies without missing information quality, using as a case study the degradation of lansoprazole under acidic, oxidative, basic, and neutral stress conditions.

Determination of Potential Genotoxic Impurity, 5-Amino-2-Chloropyridine, in Active Pharmaceutical Ingredient Using the HPLC-UV System

A novel analytical method, based on high-performance liquid chromatography with a UV (HPLC-UV) detection system for the sensitive detection of a genotoxic impurity (GTI) 5-amino-2-chloropyridine (5A2Cl) in a model active pharmaceutical ingredient (API) tenoxicam (TNX), has been developed and validated. The HPLC-UV method was used for the determination of GTI 5A2Cl in API TNX. The compounds were separated using a mobile phase composed of water (pH 3 adjusted with orthophosphoric acid): MeOH, (50:50: v/v) on a C18 column (150 × 4.6 mm i.d., 2.7 μm) at a flow rate of 0.7 mL min-1. Detection was carried out in the 254 nm wavelength. Column temperature was maintained at 40°C during the analyses and 10 μL volume was injected into the HPLC-UV system. The method was validated in the range of 1-40 μg mL-1. The obtained calibration curves for the GTI compound was found linear with equation, y = 40766x - 1125,6 (R2 = 0.999). The developed analytical method toward the target compounds was accurate, and the achieved limit of detection and limit of quantification values for the target compound 5A2Cl were 0.015 and 0.048 μg mL-1, respectively. The recovery values were calculated and found to be between 98.80 and 100.03%. The developed RP-HPLC-UV analytical method in this research is accurate, precise, rapid, simple and appropriate for the sensitive analysis of target GTI 5A2Cl in model API TNX.

Development and validation of an analytical method for quantitative determination of three potentially genotoxic impurities in vildagliptin drug material using HPLC-MS

A novel high-performance liquid chromatography-mass spectrometry method was developed to determine the quantities of pyridine, 4-dimethylaminopyridine, and N, N-dimethylaniline impurities in vildagliptin drug material. These impurities are reactive bases that may be used in synthesis of vildagliptin pharmaceutical ingredients. They are considered as potentially genotoxic impurities since they contain electrophilic functional groups. Therefore, these impurities should be monitored at the allowed limits in vildagliptin. Hence a high-performance liquid chromatography-mass spectrometry method was developed to quantify the amounts of these impurities in vildagliptin. The column was KROMASIL CN (250 mm × 3.9 mm, 3.5 μm) in reversed-phase mode. The mobile phase was a mixture of water-methanol (55:45) containing 2.5 mM ammonium acetate and 0.1% formic acid. The mass spectrometer was used to detect the amounts of impurities using selected ionization monitoring mode at m/z = 80, 122, and 123 for pyridine, N, N-dimethylaniline, and 4-dimethylaminopyridine, respectively. The flow rate was 0.5 mL/min. The sensitivity of the method was excellent at levels very less than the allowed limits. The method had excellent linearity in the concentration ranges of limit of quantification-150% of the permitted level with coefficients of determination above 0.9990. The recovery ratios were in the range of 93.70-108.63%. Results showed good linearity, precision, accuracy, sensitivity, selectivity, robustness, and solution stability.

An efficient HILIC-MS/MS method for the trace level determination of three potential genotoxic impurities in aripiprazole active drug substance

A sensitive and selective hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method was developed and validated for trace analysis of potential genotoxic impurities (PGIs): 2,3-dichloroaniline (PGI-1), bis(2-chloroethyl) amine (PGI-2), and 2-chloroethylamine (PGI-3), in aripiprazole (APZ) active drug substance. Separation of analytes was achieved on ACE HILIC–N Column (HILN-5-1046U, 100 × 4.6 mm, 5 μm) in gradient elution mode with mobile phase A [acetonitrile:ammonium formate buffer (95:5 v/v)] and mobile phase B [acetonitrile:ammonium formate buffer (50:50 v/v)] at a flow rate of 0.8 mL/min. Developed method was linear in the concentration range of 8–100 ppm for PGI-1, 11–100 ppm for PGI-2, and 12.5–100ppm for PGI-3 with R2 > 0.996. The developed method was accurate for quantification of each PGI with percent recoveries greater than 96% and RSD (%) not more than 5%. The developed method was precise for quantification of PGIs in aripiprazole with RSD (%) of not more than 4% for any of the PGIs. There was no interference of diluent peaks at the retention time of the PGIs and APZ in the method. All the PGIs and sample solutions were found to be stable at ambient laboratory temperature (25 ± 5 °C) and refrigerated condition (2–8 °C) for a period of 48 h. The developed HILIC-MS/MS method can be used for trace quantification of PGIs in aripiprazole drug in quality control laboratories of the pharmaceutical industry.

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.

Identification and genotoxicity evaluation of potential impurities in rabeprazole sodium using in silico and in vitro analyses

Rabeprazole sodium is a widely used drug for gastrointestinal disorders. Several analytical methods for identifying rabeprazole sodium and its impurities have been reported. However, the genotoxicity of rabeprazole sodium and its impurities is still unclear. Thus, it is necessary to develop analytical methods that can identify the structures of its impurities and evaluate their genotoxicity. Here, we used high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry for identifying the impurities in rabeprazole sodium enteric-coated tablets. Impurities in the samples were matched with synthesized impurities based on the exact mass and secondary mass spectrometry characteristics and then subjected to in silico analysis using the Derek and Sarah software, as well as in vitro genotoxicity evaluations. Our method successfully identified the impurities as 2-[[4-(3-methoxy propane)-3-methyl-N-oxido-2-pyridyl] methyl sulfonyl]-1H-benzimidazole (impurity I), 2-[[4-(3-methoxy propane)-3-methyl-2-pyridyl]methyl sulfonyl]-benzimidazole (impurity II), 2-[[4-(3-methoxy propane)-3-methyl-2-pyridyl] methionyl]-1H-benzimidazole (impurity III), and 2-mercapto benzimidazole (impurity IV). In silico analysis predicted that impurity III demonstrated a structural alert; thus, this impurity was evaluated for in vitro genotoxicity using the Ames test and chromosomal aberration assay. Impurity III at concentrations of 7.5-30 μg/mL had an aberration rate of over 5% with or without S-9 mix. Furthermore, impurity III at concentrations of 40-1000 μg/plate significantly increased the number of mutagenic colonies with or without S-9 mix. These results indicated that impurity III should be regulated to the limit of 0.01%.

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.

Recent Advances in Stimuli-Responsive Platforms for Cancer Immunotherapy

Immunotherapy has attracted significant interest because of its tremendous potential in cancer therapy. The recent advances in the identification of cancer-associated neoantigens, chimeric antigen receptor (CAR) T-cell and immune checkpoint blockade (ICB), have revolutionized the field of cancer immunotherapy. Cancer immunotherapeutic agents typically exhibit strong immune activation or inhibition activity, thereby inducing robust biological effect even when administered at a small dosage. However, in most cases, cancer immunotherapeutic targets are not cancer specific. Some of them are also expressed in nonmalignant normal tissues and the undesired release of the cancer immunotherapeutic agents into these normal tissues may lead to severe side effects. Thus, the on-demand release of the cancer immunotherapeutic agents into the target site is critical to achieving efficient antitumor immune responses while minimizing the side effects.In this Account, we introduce the recent progress of our group and others on the development of stimuli-responsive platforms for cancer immunotherapy. Stimuli-responsive platforms have been constructed for on-demand release of payloads in a temporally and spatially controllable manner. First, we give a brief introduction to the endogenous and exogenous stimuli that are employed to trigger the release of cancer immunotherapeutic agents. The chemical design strategies to construct the specific stimuli-responsive delivery systems are highlighted. Moreover, the recently developed representative stimuli-responsive platforms for the delivery of immune checkpoint inhibitors, indoleamine 2,3-dioxygenase (IDO) inhibitors, stimulator of interferon genes (STING) agonists, and near-infrared photoimmunotherapy (NIR-PIT) agents are discussed in detail. Meanwhile, we summarize the general chemical design for constructing stimuli-responsive delivery platforms targeting immune targets at distinct locations. Lastly, the probable issues on the clinical translation of these stimuli-responsive platforms for cancer immunotherapy are outlined. Since we are still on the way of exploring the immune system and optimizing the chemical design of biomaterials, we hope the information in this account can provide some valuable references for the development of optimal cancer immunotherapeutics.

Management of pharmaceutical ICH M7 (Q)SAR predictions - The impact of model updates

Pharmaceutical applicants conduct (Q)SAR assessments on identified and theoretical impurities to predict their mutagenic potential. Two complementary models—one rule-based and one statistical-based—are used, followed by expert review. (Q)SAR models are continuously updated to improve predictions, with new versions typically released on a yearly basis. Numerous releases of (Q)SAR models will occur during the typical 6–7 years of drug development until new drug registration. Therefore, it is important to understand the impact of model updates on impurity mutagenicity predictions over time. Compounds representative of pharmaceutical impurities were analyzed with three rule- and three statistical-based models covering a 4–8 year period, with the individual time frame being dependent on when the individual models were initially made available. The largest changes in the combined outcome of two complementary models were from positive or equivocal to negative and from negative to equivocal. Importantly, the cumulative change of negative to positive predictions was small in all models (<5%) and was further reduced when complementary models were combined in a consensus fashion. We conclude that model updates of the type evaluated in this manuscript would not necessarily require re-running a (Q)SAR prediction unless there is a specific need. However, original (Q)SAR predictions should be evaluated when finalizing the commercial route of synthesis for marketing authorization.