Identification of Two Novel Hydroperoxide Impurities in Fluocinolone Acetonide Topical Solution by Liquid Chromatography Mass Spectrometry

Fluocinolone acetonide topical is used to treat skin discomforts such as swelling, itching and redness by activating the natural substances in the skin. Several process-related impurities and degradation products are identified and reported. But hydroperoxide impurities in Fluocinolone acetonide topical solution are not reported anywhere. In this study, we identify two potential genotoxic isomeric hydroperoxide impurities in Fluocinolone acetonide topical solution by Liquid Chromatography Mass Spectrometry analysis. A possible mechanism for the formation of these two novel hydroperoxide impurities is based on the neighboring group participation effect of adjacent hydroxyl group (Internal SN2) which results in the loss of fluorine atom and formation of epoxide intermediate followed by the addition of the HOOH group. Since most of the hydroperoxide impurities are genotoxic in nature, one should eliminate these impurities from Active Pharmaceutical Ingredient (API) or protect the formulation product from these oxidative impurities.

Determination of genotoxic impurities of aromatic aldehydes in pharmaceutical preparations by high performance liquid chromatography after derivatization with N-Cyclohexyl-4-hydrazino-1,8-naphthalenediimide

The detection of aromatic aldehydes, considered potential genotoxic impurities, holds significant importance during drug development and production. Current analytical methods necessitate complex pre-treatment processes and exhibit insufficient specificity and sensitivity. This study presents the utilization of naphthalenediimide as a pre-column derivatisation reagent to detect aromatic aldehyde impurities in pharmaceuticals via high-performance liquid chromatography (HPLC). We screened a series of derivatisation reagents through density functional theory (DFT) and investigated the phenomenon of photoinduced electron transfer (PET) for both the derivatisation reagents and the resulting products. Optimal experimental conditions for derivatisation were achieved at 40 °C for 60 min. This approach has been successfully applied to detect residual aromatic aldehyde genotoxic impurities in various pharmaceutical preparations, including 4-Nitrobenzaldehyde, 2-Nitrobenzaldehyde, 1,4-Benzodioxane-6-aldehyde, and 5-Hydroxymethylfurfural. The pre-column derivatisation method significantly enhanced detection sensitivity and reduced the limit of detection (LOD), which ranged from 0.002 to 0.008 μg/ml for the analytes, with relative standard deviations < 3 %. The correlation coefficient (R2) >0.998 demonstrated high quality. In chloramphenicol eye drops, the concentration of 4-Nitrobenzaldehyde was measured to be 8.6 µg/mL below the specified concentration, with recoveries ranging from 90.0 % to 119.2 %. In comparison to existing methods, our work simplifies the pretreatment process, enhances the sensitivity and specificity of the analysis, and offers comprehensive insights into impurity detection in pharmaceutical preparations.

Development of a Triphenylmethyl Alkylation Pre-Column Derivatization Method for HPLC Quantitative Analysis of Chemically Unstable Halogenated Compounds

The primary limitations of the quantitative analysis of thermally labile halogenated compounds by traditional gas chromatography (GC) are the inadequacy of identifying the insufficiently volatile impurity (often with a high boiling point) and the difficulty in obtaining a standard substance with a reliable standardized assay. Taking the 4-(Chloromethyl)-5-methyl-1,3-dioxol-2-one (DMDO-Cl, 1) as an example, we reported a triphenylmethanamino-derivatization method to overcome the challenges of the assay determination of such species. During the quantification of 1, the presence of GC-undetectable polymeric impurity 10 poses a critical challenge in assessing the material quality. Moreover, the standard substance of 1 is not available on the market due to its inherent instability during storage and handling, further complicating the quantitative analysis. In this work, a precolumn HPLC-UV derivatization method based on triphenylmethanamino-alkylation was developed to quantitatively analyze 1. The resulting derivative 2 exhibits excellent crystallinity and superior physical and chemical stability and possesses effective chromophores for UV detection. The conversion from analyte 1 to derivative 2 demonstrates desirable reactivity and purity, facilitating quantitative analysis using the external standard method. The chemical derivatization-chromatographic detection method was optimized and validated, demonstrating its high specificity, good linearity, precision, accuracy, and stability. This method offers a valuable alternative to the general quantitative NMR (qNMR) detection technique, which exhibits reduced specificity in the presence of increased levels of impurities in compound 1.

Simultaneous and trace-level quantification of four benzene sulfonate potential genotoxic impurities in doxofylline active pharmaceutical ingredients and tablets using high-performance liquid chromatography with ultraviolet detection

In the production of doxofylline, the common occurrence of toxic p-toluene sulfonate generation prompted the development and validation of a method using HPLC with ultraviolet detection (HPLC-UV). This method is designed for detecting four potential genotoxic impurities (PGIs) present in both doxofylline drug substance and tablets, with a focus on the UV-absorbing group p-toluene sulfonate. The four impurities were methyl 4-methylbenzenesulfonate (PGI-1), ethyl 4-methylbenzenesulfonate (PGI-2), 2-hydroxyethyl 4-methylbenzenesulfonate (PGI-3), and 2-(4-methylphenyl)sulfonyloxyethyl 4-methylbenzenesulfonate (PGI-4). In this method, chromatographic separation was achieved using a Waters Symmetry C18 column (250 mm × 4.6 mm, 5 μm). The mobile phases consisted of 20% acetonitrile as mobile phase A and pure acetonitrile as mobile phase B, operating in gradient elution mode at a flow rate of 1.0 mL/min. According to the guidelines of the International Conference on Harmonization, it was determined that this method could quantify four PGIs at 0.0225 μg/mL in samples containing 60 mg/mL. The validated approach demonstrated excellent linearity (R2 > 0.999) across the concentration range of 30%-200% (relative to 0.075 μg/mL doxofylline) for the four PGIs. The accuracy of this method for the four PGIs ranged from 94.8% to 100.4%. The reverse-phase-HPLC-UV analytical method developed in this study is characterized by its speed and precision, making it suitable for the sensitive analysis of benzene sulfonate PGIs in doxofylline drug substances and tablets.

An Analytical Method for Determining N-Nitrosodimethylamine and N-Nitrosodiethylamine Contamination in Irbesartan, Olmesartan and Metformin by UPLC-APCI-MS/MS in Tablet Dosage Form

N-nitrosamine pollutants are probable carcinogens. Regulatory agencies declared their presence in the drugs unsafe for human consumption and demanded their recall. Using ultra-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (UPLC-APCI-MS/MS) in tablet dosage form based on International Conference on Harmonization (ICH) tripartite guideline criteria, we aim to develop and test a new approach for identifying and validating nitrosamine-contaminants, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) in irbesartan, olmesartan and metformin. The column was Phenomenex Luna-C18, 100 × 3.0 mm and 3.0 μm. A mobile gradient phase of formic acid in either water or methanol separated the impurities. NDMA and NDEA had retention times of 0.85 and 2.55 min, respectively. The detector's linearity was established at concentrations ranging from 0.6 to 100 ng/mL. R2 for NDMA and NDEA were 0.9996 and 0.9998, respectively, with a linear response function established at 0.6-100 ng/mL. Limit of detection and limit of quantification for NDMA and NDEA were 0.35, 0.29 and 0.55, 0.37 ng/mL, respectively. On average, recovery rates for NDMA and NDEA ranged from 96.0 to 98.4 and 96.2 to 98.0%, respectively. The relative standard deviation for NDMA and NDEA was 3.46 and 2.69, respectively. According to the ICH guidelines, the developed method was quick, sensitive and valid. The pharmaceutical formulations of irbesartan, olmesartan and metformin may be regularly examined using the approach provided here.

Determination and quantification of related substances and degradation products in bictegravir by full factorial design evaluated HPLC and mass spectrometry

Determining and quantifying novel impurities and degraded impurities of a drug product is always a continuous challenge to enhancing the drug quality for patients' safety. Herein, our work deals with (i) developing a rapid, accurate, and reliable high-performance liquid chromatographic validation method to quantify the bictegravir drug (integrase inhibitors of antiretroviral drugs) and its novel related impurities at low levels, and (ii) the liquid chromatography-mass spectrometry (LC-MS) method to identify degraded impurities. Separation of bictegravir acid (impurity-I) and methyl bictegravir (impurity-II) impurities which are identified by LC-MS in the bictegravir drug was executed by developing a method and the same method performance evaluated by using full factorial design. This developed analytical technique gave a well-separated peak of bictegravir and related analytes such as bictegravir acid (impurity-I) and methyl bictegravir (impurity-II), adequate with the peak properties as per USP guidelines. The method's sensitivity and linearity are demonstrated by its detection and quantification limits at low levels with a correlation coefficient of 0.998. The method's repeatability, specificity, and accuracy suggest that this developed technique is a reliable determination strategy for the bictegravir drug substance and its related impurities (impurity-I and impurity-II) in a simple, feasible, and affordable way.

A fluorescent probe for alkylating agents and its quantification of triflate as a genotoxic impurity

The responses of a reaction-based fluorescent probe BI-Py towards alkyl halide, epoxide, carbonate, sulfate, sulphonate and triflate were evaluated and the probe achieved selective detection of ethyl triflate in acetonitrile with a LOD of 1.08 μM. BI-Py exhibited great potential for detecting triflate as a genotoxic impurity in drug substances.

Identification and validation of potential genotoxic impurities, 1,3-dichloro-2-propanol, and 2,3-dichloro-1-propanol, at subtle levels in a bile acid sequestrant, colesevelam hydrochloride, using hyphenated GC-MS technique

Potential genotoxic impurities (PGI) and N-nitrosamine impurities in active pharmaceutical ingredients (APIs) and their determination at low levels are substantial challenges for cholesterol-lowering agents in recent years. Herein we developed a robust, reliable, rapid, accurate and validated technique of gas chromatography equipped with a mass spectrometer (GC-MS) for quantifying subtle levels of 1,3-dichloro-2-propanol (PGI-I) and 2,3-dichloro-1-propanol (PGI-II) in colesevelam hydrochloride drug substance (bile acid sequestrant). The separation of colesevelam hydrochloride, PGI-I and PGI-II was executed with chromatographic technique using a capillary column, DB-624 measuring with 30 m × 0.32 mm × 1.8 μm specification of 6% cyanopropylphenyl-94% dimethylpolysiloxane copolymer and helium carrier gas. This developed technique gave a good intensity peak without any interference and extra masses at the retention times of 11.17 min for PGI-I and 11.59 min for PGI-II, which was adequate, with mass spectra (m/z) of 79 and 62, respectively. The method's sensitivity and linearity are demonstrated by its detection and quantification limits at subtle levels with correlation coefficients of 0.9965 for PGI-I and 0.9910 for PGI-II. The determination is mainly focused on improving sensitivity with the limits of detection and quantitation far below the specifications, which can support tighter limits. This results in a cost-effective and easily adoptable methodology having precise and accurate results in colesevelam hydrochloride API at subtle levels.

Development and Validation for Quantification of 7-Nitroso Impurity in Sitagliptin by Ultraperformance Liquid Chromatography with Triple Quadrupole Mass Spectrometry

The purpose of this research study was to develop an analytical method for the quantification of 7-nitroso-3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4] triazolo [4,3-a] pyrazine (7-nitroso impurity), which is a potential genotoxic impurity. Since sitagliptin is an anti-diabetic medication used to treat type 2 diabetes and the duration of the treatment is long-term, the content of nitroso impurity must be controlled by using suitable techniques. To quantify this impurity, a highly sensitive and reproducible ultraperformance liquid chromatography with triple quadrupole mass spectrometry (UHPLC-MS/MS) method was developed. The analysis was performed on a Kromasil-100, with a C18 column (100 mm × 4.6 mm with a particle size of 3.5 µm) at an oven temperature of approximately 40 °C. The mobile phase was composed of 0.12% formic acid in water, with methanol as mobile phases A and B, and the flow rate was set to 0.6 mL/min. The method was validated according to the current International Council for Harmonisation (ICH) guidelines with respect to acceptable limits, specificity, reproducibility, accuracy, linearity, precision, ruggedness and robustness. This method is useful for the detection of the impurity at the lowest limit of detection (LOD), which was 0.002 ppm, and the lowest limit of quantification (LOQ), which was 0.005 ppm. This method was linear in the range of 0.005 to 0.06 ppm and the square of the correlation coefficient (R2) was determined to be > 0.99. This method could help to determine the impurity in the regular analysis of sitagliptin drug substances and drug products.

Spectrofluorimetric determination of selected genotoxic impurities in pharmaceutical raw materials and final products

A green spectrofluorimetric method was introduced for the determination of selected genotoxic impurities; 2-aminopyridine and 3-aminopyridine in different pharmaceutical raw materials and dosage forms. The method relied on the native fluorescence of these impurities in acidic medium. The experimental conditions were carefully studied and optimized, and the method was validated according to International Council on Harmonisation (ICH) guidelines. The linear range for both analytes was 2.50–100 ng/mL with good determination coefficients of 0.9995 and 0.9992 and detection limits of 0.62 ng/mL and 0.74 ng/mL for 2-aminopyridine and 3-aminopyridine, respectively. The method was successfully applied for determination of 2-aminopyridine and 3-aminopyridine in four active pharmaceutical ingredients and nine dosage forms with satisfactory percentage recoveries and without interference from co-formulated excipients. Analytical performance of the proposed method was comparable to that of the reported methods; hence, the proposed method can be used as a simple and low-cost alternative in quality control laboratories.

Determination of Three Alkyl Camphorsulfonates as Potential Genotoxic Impurities Using GC-FID and GC-MS by Analytical QbD

Camphorsulfonic acid salts are commonly used in the manufacturing production of active pharmaceutical ingredients (APIs) and have the potential to form alkyl camphorsulfonates, which can be considered as potential genotoxic impurities (PGIs). Alkyl camphorsulfonates should be controlled using the Threshold of Toxicological Concern (TTC) when detected in APIs due to their genotoxicity. An in silico study utilizing the ICH M7 guideline was performed in order to classify the alkyl camphorsulfonates that can be produced from the reaction of camphorsulfonic acid salts with methanol, ethanol, and isopropyl alcohol, which are commonly used solvents in API manufacturing processes. Two sensitive, reproducible, and accurate analytical methods using GC-FID and GC-MS were developed using the analytical Quality By Design (QbD) approaches for the quantitation of three alkyl camphorsulfonates in APIs satisfying the control limit of PGIs according to the TTC. The detection limits of the GC-FID method were found to be between 1.5 to 1.9 ppm, and the detection limits of the GC-MS method were found to be between 0.055 to 0.102 ppm. The method was validated in terms of accuracy, linearity, precision, detection limit, quantitation limit, specificity and robustness.

A colorimetric and fluorometric probe for phenylhydrazine and its application in real samples

A fluorescent probe for phenylhydrazine detection was developed with aldehyde as the recognition group and good selectivity towards phenylhydrazine over hydrazine, hydroxylamine and other amines was observed. Its application in real water samples and fast visualization of phenylhydrazine using a probe-loaded paper strip were demonstrated.

Quantitative Determination of Four Potential Genotoxic Impurities in the Active Pharmaceutical Ingredients in TSD-1 Using UPLC-MS/MS

A novel method of ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed for the identification and quantification of four potential genotoxic impurities (PGIs) in the active pharmaceutical ingredients of TSD-1, a novel P2Y12 receptor antagonist. Four PGIs were named, 4-nitrobenzenesulfonic acid, methyl 4-nitrobenzenesulfonate, ethyl 4-nitrobenzenesulfonate, and isopropyl 4-nitrobenzenesulfonate. Following the International Conference of Harmonization (ICH) guidelines, this methodology is capable of quantifying four PGIs at 15.0 ppm in samples of 0.5 mg/mL concentration. This validated approach presented very low limits (0.1512−0.3897 ng/mL), excellent linearity (coefficients > 0.9900), and a satisfactory recovery range (94.9−115.5%). The method was sufficient in terms of sensitivity, linearity, precision, accuracy, selectivity, and robustness and, thus, has high practicality in the pharmaceutical quality control of TSD-1.

Determination of Methyl Methanesulfonate and Ethyl Methylsulfonate in New Drug for the Treatment of Fatty Liver Using Derivatization Followed by High-Performance Liquid Chromatography with Ultraviolet Detection

A new derivatization high-performance liquid chromatography method with ultraviolet detection was developed and validated for the quantitative analysis of methanesulfonate genotoxic impurities in an innovative drug for the treatment of non-alcoholic fatty liver disease. In this study, sodium dibenzyldithiocarbamate was used as a derivatization reagent for the first time to enhance the sensitivity of the analysis, and NaOH aqueous solution was chosen as a pH regulator to avoid the interference of the drug matrix. Several key experimental parameters of the derivatization reaction were investigated and optimized. In addition, specificity, linearity, precision, stability, and accuracy were validated. The determined results of the samples were consistent with those obtained from the derivatization gas chromatography–mass spectrometry analysis. Thus, the proposed method is a reliable and practical protocol for the determination of trace methanesulfonate genotoxic impurities in drugs containing mesylate groups.

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.

Taking the Green Road Towards Pharmaceutical Manufacturing

The introduction of the Green Chemistry Principles in the late 1990s formed the basis for a transition to a greener environment. These Principles have become an integral part in the work on designing chemical processes, especially for large-scale manufacture. The ultimate target is the achievement of a sustainable production method allowing hundreds of tons of valuable materials to be prepared. For this purpose, a holistic view must be applied to the elements constituting a fully-fledged process encompassing layout of the synthetic route, defining starting materials and their origin, output of product and quality features, quantity of effluent streams and waste, recovery and recycling of chemicals involved, and energy consumption. These parameters form a complex matrix where the individual components are in a complicated relationship with each other. This short review addresses these issues and the benefits of life-cycle assessment and metrics commonly used to measure the performance of chemical manufacturing – all from a pharmaceutical industry perspective as experienced by the author.

1 Introduction: Facing Severe Challenges

2 The Historical Context: Addressing an Image Problem

3 Prospects, Drivers and Roadmap for the Green Future

4 Living by the Principles: Industrial Perspectives

5 Taking the Green Route – Catalysis Leading the Way: Case Stories

6 State of the Art: How Green Are We?

7 Sending Signals, Creating Impressions: Focus on Communication

8 Conclusions

A rapid and sensitive UPLC-MS/MS method for simultaneous determination of four potential mutagenic impurities at trace levels in ripretinib drug substance

In the synthesis of ripretinib, a new oral tyrosine kinase inhibitor, impurities could arise directly from starting materials, reagents and intermediates. Among these process impurities, four specific intermediate impurities were found to contain the structural alerts of primary aromatic amine and aldehyde groups, triggering the concern of potential mutagenic impurities (PMIs). Two complementary (quantitative) structure–activity relationship [(Q)SAR] evaluation systems (expert rule-based and statistics-based) were subsequently employed to assess and classify the mutagenic risk of the four known impurities. The Sarah prediction results of these four impurities were all positive and they were categorized as class 3, where the threshold of toxicological concern (TTC) of 1.5 μg d⁻¹ would apply. Hereby, a rapid and sensitive UPLC-MS/MS method was developed for the simultaneous and trace level quantification of the four PMIs in ripretinib drug substance. The separation was achieved on a C18 column under the optimized gradient elution program consuming only nine minutes and the four PMIs were all well separated from ripretinib so that they could be easily diverted to waste via a switch valve. The time-segmented multiple reaction monitoring (MRM) mode further improved the sensitivity and allowed for the quantification of the four PMIs as low as 10% of the acceptable limit. The method was fully validated, and proved sufficient in terms of selectivity, sensitivity, linearity, precision and accuracy. The factors involved in the method development and pathways for fragment ions of the four PMIs were also discussed and the study will contribute to risk management of PMIs present in ripretinib.

Evaluation and classification of the mutagenicity of impurities using two (Q)SAR tools and UPLC-MS/MS method for the simultaneous and trace level quantification of four PMIs in ripretinib.

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.

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.

Development and Validation of a UPLC-MS/MS Method for Ultra-Trace Level Determination of Acyl Chloride Potential Genotoxic Impurity in Mezlocillin

3-Chlorocarbonyl-1-methanesulfonyl-2-imidazolidinone (CMI) is a critical intermediate used in the synthesis of mezlocillin drug substance and also a potential genotoxic impurity with acyl chloride moiety. The content of CMI in mezlocillin should be <0.16 ppm to avoid the carcinogenicity and mutagenicity threats to patients. Therefore, a workable determination of CMI was critically crucial for ensuring the safety of mezlocillin drug products. However, the conventional HPLC method is insufficient for detection limits at ppm or lower levels. Besides, the high activity of acyl chloride also raises a challenge to the direct measurement of CMI. Thus, we explored a simple esterification approach, which converts CMI into methyl 3-(methylonyl)-2-oxoimidazolidine-1-carboxylate completely by optimizing the reaction temperature and time. Furthermore, the selected reaction monitoring model of triple quadrupole mass spectrometer optimized by the Box-Behnken design significantly enhanced the sensitivity of ultra-trace level determination. The limit of detection and limit of quantification of the method were reached 0.014 and 0.02 ppm, respectively, in the following validation study. A sensitive and specific ultra-performance liquid chromatography tandem mass spectrometry method for ultra-trace level determination of acyl chloride potential genotoxic impurity in mezlocillin drug substance has been successfully established in this study, which will provide a practical quality control tool of mezlocillin.

NDMA analytics in metformin products: Comparison of methods and pitfalls

BACKGROUND

For nearly three years, the concerns regarding trace levels of N-nitrosamines in pharmaceuticals and the associated cancer risk have significantly expanded and are a major issue facing the global pharmaceutical industry. N-nitrosodimethylamine (NDMA) found in formulations of the popular anti-diabetic drug metformin is a prominent example. This has resulted in product recalls raising the profile within the media. Issues of method robustness, sample preparation and several unexpected sources of nitrosamine contamination have been highlighted as false positive risks. It has become apparent that the identification of the root causes of artefactual formation of nitrosamines must be identified to mitigate risk associated with the analysis.

METHODS

A comparison study between four laboratories, across three companies was designed, employing orthogonal mass spectrometric methods for the quantification of NDMA in two metformin immediate release (IR) formulations and one extended release (XR) formulation. These were 2x LC-MS/MS, GC-MS/MS and GC-HRMS.

RESULTS

Good agreement of results was obtained for the IR formulations. However, we measured higher concentrations of NDMA in the XR formulation using GC-MS/MS compared to LC-MS/MS. We could show that this was due to artefactual (in situ) formation of NDMA when samples were extracted with dichloromethane. Removal of dimethylamine (DMA) and nitrite from the extracted sample or the addition of a nitrosation scavenger are shown to be effective remedies. NDMA in situ formation was not observed in 10% MeOH or acetonitrile.

CONCLUSION

Metformin pharmaceuticals contain traces of the API impurity DMA as well as inorganic nitrite from excipients. This can lead to artefactual formation of NDMA and hence false positive results if DCM is used for sample extraction. Similar artefacts are likely also in other pharmaceuticals if these contain the secondary amine precursor of the respective nitrosamine analyte.

Lopinavir/Ritonavir: A Review of Analytical Methodologies for the Drug Substances, Pharmaceutical Formulations and Biological Matrices

Lopinavir/ritonavir is a potent coformulation of protease inhibitors used against HIV infection. Lopinavir is the main responsible for viral load suppression, whereas ritonavir is a pharmacokinetic enhancer. Both of them have recently gained relevance as candidate drugs against severe coronavirus disease (COVID-19). However, significant beneficial effects were not observed in randomized clinical trials. This review summarizes the main physical-chemical, pharmacodynamic, and pharmacokinetic properties of ritonavir and lopinavir, along with the analytical methodologies applied for biological matrices, pharmaceutical formulations, and stability studies. The work also aimed to provide a comprehensive impurity profile for the combined formulation. Several analytical methods in four different pharmacopeias and 37 articles in literature were evaluated and summarized. Chromatographic methods for these drugs frequently use C8 or C18 stationary phases with acetonitrile and phosphate buffer (with ultraviolet detection) or acetate buffer (with tandem mass spectrometry detection) as the mobile phase. Official compendia methods show disadvantages as extended total run time and complex mobile phases. HPLC tandem-mass spectrometry provided high sensitivity in methodologies applied for human plasma and serum samples, supporting the therapeutic drug monitoring in HIV patients. Ritonavir and lopinavir major degradation products arise in alkaline and acidic environments, respectively. Other non-chromatographic methods were also summarized. Establishing the impurity profile for the combined formulation is challenging due to a large number of impurities reported. Easier and faster analytical methods for impurity assessment are still needed.

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.

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.

A simple and sensitive LC-MS/MS method for determination and quantification of potential genotoxic impurities in the ceritinib active pharmaceutical ingredient

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used for quantification of four potential genotoxic impurities (PGIs) in the ceritinib active pharmaceutical ingredient. Chromatographic separation was achieved using a YMC-Triart C18 column, with 0.1% formic acid in water as mobile phase A and acetonitrile as mobile phase B in gradient elution mode at a 0.5 mL min-1 flow rate. Quantification of impurities was carried out using triple quadrupole mass detection with electrospray ionization in multiple reaction monitoring mode. The method was fully validated with good linearity over the concentration range of 0.5-5.0 ppm of the ceritinib test concentration for all four PGIs. The correlation coefficient obtained in each case was >0.998. The recoveries were found satisfactory over the range between 83.7 and 107.3% for all selected impurities. The developed method was able to quantitate all four PGIs at a concentration level of 1 ng mL-1 (0.5 ppm with respect to 2 mg mL-1 ceritinib).

UHPLC-fluorescence method for the determination of trace levels of hydrazine in allopurinol and its formulations: Validation using total-error concept

The present approach poses an interesting way to quantify residues of the genotoxic impurity hydrazine in allopurinol and its pharmaceutical formulations using ultra high performance liquid chromatography coupled to fluorescence detection. Hydrazine was pre-column derivatized through a unique chemistry with o-phthalaldehyde under acidic conditions. Using highly acidic mobile phase the derivative exhibits a strong fluorescence intensity. Derivatization and chromatographic parameters were thoroughly investigated. The validation of the developed method has been carried out in the range of 10 to 200% of the target concentration limit of the analyte using the accuracy profiles as a graphical decision-making tool. The β-expectation tolerance intervals did not exceed the acceptance criteria of ±20% which means that 95% of future results will be included in the defined bias limits. The variation of the relative bias ranged between -6.0 and 0.5% and the RSD values for repeatability and intermediate precision were lower than 6.9% in all cases. The limit of detection (LOD) and the lower limit of quantification (LLOQ) were satisfactory and found to be 0.3 ng mL^-1 (corresponding to 0.03 μg g^-1 in solid sample). Experimental designs were constructed to study the robustness of the instrumental method and the derivatization procedure. The developed method has been successfully applied for the analysis of hydrazine in allopurinol API batches and tablets indicating that this methodology could be adopted from QC laboratories.

Development and Validation of LC-MS/MS for Analyzing Potential Genotoxic Impurities in Pantoprazole Starting Materials

Pantoprazole sodium (PPZS) is a selective proton pump inhibitor used in the prevention and treatment of gastric acid-related diseases. Six potentially genotoxic impurities (PGIs) are involved in 5-difluoromethoxy-2-mercapto-1H-benzimidazole (DMBZ), which is the starting material of PPZS. To date, no suitable method has yet been developed for PGI separation and quantification at the threshold of toxicological concern levels. In this study, a sensitive and reliable liquid chromatography-tandem mass spectrometry method was developed and validated for the quantitative analysis of six PGIs in DMBZ according to the guidelines of the International Council for Harmonization (ICH). The calibration curves showed good linearity within the studied range, and the correlation coefficient of fitting exceeded 0.998 for each impurity. The sensitivity of the proposed method was in the range of 0.6-10.0 ng/mL. Good recoveries were observed in the range of 94.32%-107.43% with RSD values below 6.5%. Quantitative analysis of impurities in substance batches of DMBZ showed the high efficiency of the developed method at a low level. Hence, the proposed method is practical and useful in the detection and qualification of PGIs in DMBZ and may be applied to ensure the safe use of PPZS in clinical treatment.

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.

Prediction of toxicity of secondary metabolites

The prediction of toxicological endpoints has gained broad acceptance; it is widely applied in early stages of drug discovery as well as for impurities obtained in the production of generic or equivalent products. In this work, we describe methodologies for the prediction of toxicological endpoints compounds, with a particular focus on secondary metabolites. Case studies include toxicity prediction of natural compound databases with anti-diabetic, anti-malaria and anti-HIV properties.

Simultaneous Determination of 15 Sulfonate Ester Impurities in Phentolamine Mesylate, Amlodipine Besylate, and Tosufloxacin Tosylate by LC-APCI-MS/MS

Sulfonate esters have been recognized as potential genotoxic impurities (PGIs) in pharmaceuticals. An LC-MS/MS method was developed and validated for the simultaneous determination of 15 sulfonate esters, including methyl, ethyl, propyl, isopropyl, and n-butyl esters of methanesulfonate, benzenesulfonate, and p-toluenesulfonate in drug products. The method utilized atmospheric pressure chemical ionization (APCI) in multiple reaction monitoring (MRM) mode for the quantitation of impurities. The method employed an ODS column as the stationary phase and water-acetonitrile as the solvents for gradient elution without derivatization steps. The method was specific, linear, accurate, precise, and robust. Recoveries of the sulfonic esters from three drug matrices were observed in the range of 91.6∼109.0% with an RSD of not greater than 17.9% at the concentration of the LOQ and in the range of 90.4%∼105.2% with an RSD of not greater than 7.1% at the concentration of 50 ng/mL for the methanesulfonates and 10 ng/mL for the benzenesulfonates and p-toluenesulfonates. The LOD was not greater than 15 ng/mL, 2 ng/mL, and 1 ng/mL for the methanesulfonate, benzenesulfonate, and p-toluenesulfonate esters, respectively. This method was sufficiently sensitive to detect the 15 PGIs in the phentolamine mesylate tablet, amlodipine besylate tablet, and tosufloxacin tosylate tablet. This analytical method is a direct, specific, rapid, and accurate quality control tool for the determination of the 15 sulfonate esters that are most likely to exist in drug products.

A simple, sensitive, and straightforward LC-MS approach for rapid analysis of three potential genotoxic impurities in rabeprazole formulations

In the present study, a sensitive and fully validated liquid chromatography with mass spectrometry method was developed for the quantification of three potential genotoxic impurities in rabeprazole drug substance. The separation was achieved on Symmetry C18 column (100 × 4.6 mm, 3.5 μm) using 0.1% formic acid in water as mobile phase A and acetonitrile as mobile phase B in gradient elution mode at 0.5 mL/min flow rate. Triple quadrupole mass detection with electrospray ionization was operated in selected ion recording mode for the quantification of impurities. The calibration curves were demonstrated good linearity over the concentration range of 1.0-4.5 ppm for O-phenylenediamine, 1.8-4.5 ppm for 4-nitrolutidine-N-oxide and 1.0-4.5 ppm for benzyltriethylammonium chloride with respect to 10 mg/mL of rabeprazole. The correlation coefficient obtained in each case was >0.998. The recoveries were found satisfactory over the range between 94.22 and 106.84% for all selected impurities. The method validation was carried out following International Conference on Harmonization guidelines, from which the developed method was able to quantitate the impurities at 1.0 ppm for O-phenylenediamine, 1.8 ppm for 4-nitrolutidine-N-oxide and 1.0 ppm for benzyltriethylammonium chloride. Furthermore, the proposed method was successfully evaluated for the determination of selected impurities from bulk drug and formulation samples of rabeprazole within the acceptable limits.