Oxidative Degradation Products Research Articles

Separation of Empagliflozin and its Impurities by Validated Stability Indicating HPLC Method and LC-MS Characterization of Oxidative Degradation Product

The HPLC assay strategy for two impurities (EPN-R-ISO impurity and the EPN-Diol impurity) which are related to empagliflozin synthesis was designed and verified for the reliable measurement of EPN-R-ISO and EPN-Diol impurities in empagliflozin bulk APIs. The chromatographical EPN-R-ISO and the EPN-Diol impurities analysis was done on Discovery C18 stationery column with isocratic type mobile phase exploited was potassium dihydrogenphosphate (0.01 M, pH calibrated to 2.0 by phosphoric acid) and acetonitrile in 70%:30% v/v ratio and injected at a flow measure of 1.0 mL/min. The degradation of empagliflozin under stressful conditions such as acid generated hydrolysis, base generated hydrolysis, peroxide generated oxidation, thermal generated degradation and UV generated hydrolysis was also included. The method established was verified for precision (0.0837% RSD for EPN-R-ISO; 0.1831% RSD for EPN-Diol), sensitivity (LOD: 0.030262 ppm EPN-R-ISO concentration, 0.031873 ppm EPN-Diol concentration; LOQ: 0.092621 ppm EPN-R-ISO concentration, 0.09755 ppm EPN-Diol concentration), linearity (0.1 ppm to 90.0 ppm concentration of both EPN-R-ISO and EPN-Diol) and accuracy (95.07% to 96.27% EPN-R-ISO recovery; 97.72% to 100.03% EPN-Diol recovery).

Isolation and structural characterization of two novel oxidative degradation products of losartan potassium active pharmaceutical ingredient using advanced analytical techniques.

Losartan potassium (losartan) is the most frequently utilized antihypertensive medication in the world. However, partial oxidation of losartan produces toxic by-products that could be harmful to living organisms. Therefore, it is necessary to degrade the losartan and identify the potential toxic oxidative degradation products to minimize their formation during manufacturing, formulation, storage, and packing conditions. Oxidative degradation experiments of losartan were performed according to ICH guidelines. The degradation products were detected using ultra-high-performance liquid chromatography-mass spectrometry analysis, isolated by using preparative HPLC, and identified by using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopic techniques. The degradation products (DP-1, DP-2, and DP-3) were identified as (((2'-(2H-tetrazol-5-yl)-[1,1'-biphenyl]-4-yl)methyl)amino)-2-oxoethylpentanoate, 5-(4'-((2 butyl-4-chloro-5-(hydroxymethyl)-1H-imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-yl)-1H tetrazol-1-ol, and 5-(4'-((2-butyl-4-chloro-5-(hydroxymethyl)-1H-imidazol-1 yl)methyl)-[1,1'-biphenyl]-2-yl)-2H-tetrazol-2-ol, respectively. Forced degradation of losartan potassium API under oxidative condition indicates the formation of two major novel oxidative degradation products (DP-2 and DP-3) and one minor known degradation product (DP-1).Preparative HPLC used for the isolation of the resultant DPs and their structures were successfully established using UHPLC-MS, 1H NMR, 13C NMR, HSQC, HMBC, and HRMS spectroscopic techniques.

COMPUTATIONAL DRUG REPROPOSING TO IDENTIFY SARS-COV-2 MPRO INHIBITORS: MOLECULAR DOCKING, ADMET ANALYSIS, AND IN-SILICO/IN-VITRO TOXICITY STUDY

Aim and Objective: After the COVID-19 outbreak, drug repurposing has emerged as an effective and fast approach for combating the SARS-CoV-2 crisis. in this work, computational drug repurposing has been utilized to identify new SARS-CoV-2Mpro inhibitors. Methods: Comparative molecular docking studies were used to evaluate the activity of the commercially available oral antiviral drug simeprevir and its degradation products (compounds 1–5) against the main protease (Mpro)of SARS-CoV-2 (PDB ID: 6lu7; resolution: 2.16 Å). Moreover, the ADMET and in-silico toxicity properties of the acidic (compounds 1–3) and oxidative (compounds 4 and 5) degradation products of simeprevir were predicted. Results: Docking studies revealed good binding affinities for compounds (1–5) against Mpro of SARS-CoV-2, with binding free energies ranging from −6.23 to −7.65 kcal/mol. The acidic degradant 2 exhibited the best affinity and was superior to simeprevir and a natural ligand. All compounds were expected to be safe to the CNS. Conclusion: Compounds 1, 4, and 5 were expected to possess good human intestinal absorption, whereas compounds 2 and 3 appeared to have moderate intestinal absorption. Peer Review History: Received: 1 September 2022; Revised: 11 October; Accepted: 6 November, Available online: 15 November 2022 Academic Editor: Dr. DANIYAN Oluwatoyin Michael, Obafemi Awolowo University, ILE-IFE, Nigeria, toyinpharm@gmail.com Received file: Reviewer's Comments: Average Peer review marks at initial stage: 5.5/10 Average Peer review marks at publication stage: 7.0/10 Reviewers: Dr. Gehan Fawzy Abdel Raoof Kandeel, Pharmacognosy Department, National Research Centre, Dokki, 12622, Giza, Egypt, gehankandeel9@yahoo.com Dr. Nicola Micale, University of Messina, Italy, nmicale@unime.it Prof. Cyprian Ogbonna ONYEJI, Obafemi Awolowo University, Ile-Ife, Nigeria, conyeji@oauife.edu.ng Similar Articles: USE OF COLCHICINE TO COUNTERACT THE STRONG HYPERINFLAMMATORY STATE INDUCED BY SARS-COV-2 THE ROLE OF ANTICOAGULANTS AND ANTIPLATELETS IN PROPHYLAXIS AND/OR TREATMENT OF SEVERE SARS-COV-2 INFECTION

Organofluorophosphates as Oxidative Degradation Products in High-Voltage Lithium Ion Batteries with NMC or LNMO Cathodes

Organofluorophosphates (OFPs) have been reported to pose substantial health hazards due to their structural similarities to pesticides and nerve agents. Formation of OFPs in lithium ion batteries (LIBs) due to hydrolysis of the conducting salt lithium hexafluorophosphate (LiPF6) and the reaction with the organic carbonate solvents that make up the electrolyte has been discussed in literature. The oxidative formation of OFPs in electrolytes containing fluoroethylene carbonate (FEC) and vinylene carbonate (VC) as film-forming additives is presented in this study. Further the impact of potentially reactive positive electrode surfaces is investigated with the layered metal oxide NCM622 which is ascribed to release reactive oxygen species at high voltages and the spinel type LNMO as a typical high-voltage material. Cycling of the self-assembled LIB coin cells (CR2032) at cut-off voltages of 4.8 V gave rise to a number of degradation products including potentially highly toxic OFPs. Here, the presence of the film-forming additive had a massive impact on the amount of OFPs formed during electrochemical cycling experiments, which raises further concerns for the utilization of film-forming additives for high voltage applications. The formation pathway of OFPs through EC-polymerization proposed in literature is evaluated and an alternative mechanism with FEC/VC as the carbonyl carbon-donor is presented. Structure elucidation and separation of the formed OFPs is achieved by utilization of reversed-phase (RP) chromatography hyphenated to a high-resolution ion trap time-of-flight mass spectrometer (IT-TOF-MS). The findings presented in this study support further investigation of the formation of OFPs in film-forming additive-containing electrolytes, quantitative approaches and toxicological assessments due to the highly toxic nature of OFPs.

Development of stability-indicating method for separation and characterization of benidipine forced degradation products using LC-MS/MS.

The present study describes forced degradation of benidipine (BEN) as per Q1A (R2) and Q1B guidelines of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. BEN degraded under hydrolysis (neutral, acidic, and alkaline), hydrogen peroxide induced oxidation, and UV light mediated photolytic degradation. A total of 14 degradation products (DPs) were found in all degradation studies, comprising 4 hydrolytic DPs, 8 oxidative DPs, and 4 photolytic DPs. A selective stability-indicating method was developed using an XBridge BEH C18 column with gradient elution program consisting of ammonium acetate (10mM, 4.8 pH, acetic acid) and acetonitrile. The flow rate was maintained at 1ml min-1 . All DPs were separated well using the developed HPLC method and were characterized using LC-MS/MS data. As this method is effective in identifying and separating BEN and its DPs with sufficient resolution, it can be used in laboratories for quality control of drugs in daily routine analysis and stability studies.

Lipid Peroxidation Linking Diabetes and Cancer: The Importance of 4-Hydroxynonenal.

Significance: It is commonly believed that diabetes mellitus may be associated with cancer. Hence, diabetic patients are at higher risk for hepatocellular carcinoma, pancreatic cancer, colorectal cancer, and breast cancer, but the mechanisms that may link these two severe diseases are not well understood. Recent Advances: A number of factors have been suggested to promote tumorigenesis in diabetic patients, including insulin resistance, hyperglycemia, dyslipidemia, inflammation, and elevated insulin-like growth factor-1 (IGF-1), which may also promote pro-oxidants, and thereby alter redox homeostasis. The consequent oxidative stress associated with lipid peroxidation appears to be a possible pathogenic link between cancer and diabetes. Critical Issues: Having summarized the above aspects of diabetes and cancer pathology, we propose that the major bioactive product of oxidative degradation of polyunsaturated fatty acids (PUFAs), the reactive aldehyde 4-hydroxynonenal (4-HNE), which is also considered a second messenger of free radicals, may be the key pathogenic factor linking diabetes and cancer. Future Directions: Because the bioactivities of 4-HNE are cell-type and concentration-dependent, are often associated with inflammation, and are involved in signaling processes that regulate antioxidant activities, proliferation, differentiation, and apoptosis, we believe that further research in this direction could reveal options for better control of diabetes and cancer. Controlling the production of 4-HNE to avoid its cytotoxicity to normal but not cancer cells while preventing its diabetogenic activities could be an important aspect of modern integrative biomedicine. Antioxid. Redox Signal. 37, 1222-1233.

Structural characterization of novel hydrolytic and oxidative degradation products of acalabrutinib by LC-Q-TOF-MS, H/D exchange and NMR

The drug substance, acalabrutinib was subjected to hydrolytic (acid, base and neutral) and oxidative stress degradation as per ICH recommendations. Degradation products (DPs) generated from the drug substance were separated on a Shimadzu Shim-pak C-8 column utilizing a mobile phase composed of methanol: acetonitrile (90:10 v/v) and ammonium acetate buffer (10 mM, pH 3.80) in a gradient elution mode. Acalabrutinib was found to be labile under acid, basic, neutral and oxidative conditions. A total of eighteen DPs of drug substance were formed in hydrolytic (fourteen DPs) and oxidative degradation conditions (four DPs). All the DPs were characterized by comparing the LC-Q-TOF mass spectrometric fragmentation pathway of the drug substance with DPs. Further, hydrogen/deuterium (H/D) exchange studies were also carried out on the DPs to confirm the presence of labile hydrogens in their structures. Four DPs (H-12, O-2, O-3 and O-4) were isolated for chemical structural elucidation by NMR. Probable mechanisms involved in degradation of acalabrutinib were also postulated.

Degradation of carbendazim in aqueous solution by dielectric barrier discharge cold plasma: Identification and toxicity of degradation products

Dielectric barrier discharge (DBD) cold plasma, as a new nonthermal technology, has attracted increasing attention in pesticide degradation. In this study, DBD plasma was used to degrade carbendazim (MBC) in aqueous solution. Under the optimal conditions (160 kv, 50 Hz), MBC solution (0.5 μg/mL) was degraded by 89.04% after plasma treatment for 10 min. Four MBC degradation products were identified, one of which was a common oxidative degradation product (5-hydroxycarbendazim, m/z 208.07); the others were identified (m/z 118.06, m/z 132.08 and m/z 104.05) to have formed by the cleavage of the benzimidazole heterocyclic ring. The degradation pathways were obtained by analysis of degradation products at different treatment times. The toxicity of the degradation products was estimated based on the survival rate of yeast, indicating much lower toxicity levels compared to that of MBC. This study provides a theoretical basis for the application of DBD plasma in the degradation of benzimidazole pesticides in foods.

A Validated Stability-Indicating HPLC-PDA Method for Tolnaftate: Identification, Characterization and In Silico Toxicity Predictions of Major Degradation Products.

Simple and rapid stability indicating High Performance Liquid Chromatography-Photo Diode Array (HPLC-PDA) method was developed and validated for the estimation of tolnaftate in the presence of its forced degradation products. The method employed SunQSil C18 column (250mm × 4.6mm, 5μm) as stationary phase and acetonitrile:water (85:15, v/v) as mobile phase. Retention time of tolnaftate was 6.9min. Acid and alkali hydrolysis, oxidation, photo degradation and thermal degradation studies were carried out to evaluate the degradation behavior of tolnaftate. The developed and optimized method was validated as per International Conferences on Harmonization (ICH) guidelines. Limit of detection and limit of quantitation were found to be 0.092 and 0.276μg/mL, respectively. Linearity was observed in a concentration range of 0.276-6μg/mL with R2= 0.9936. %Recovery was found to be between 98.28% and 100.71%. The developed and validated Reversed Phase-High Performance Liquid Chromatography (RP-HPLC) method was successfully applied for quantification of tolnaftate in in-house topical solution. Major base and oxidative degradation products were identified and characterized by liquid chromatography-electrospray ionization mass spectrometry. The probable mechanisms for the formation of degradation products were predicted based on the fragmentation pattern of degradation products. The in silico dermal penetration predictions and carcinogenicity of degradation products were evaluated by using QikProp and CarcinoPred-EL functionality.

Novel Eco-Friendly Stability Indicating Capillary Zone Electrophoresis Method for Determination of Aripiprazole in Tablet Dosage form: DoE Directed Optimization, Development and Method Validation

In this work, a novel environment-friendly stability indicating capillary zone electrophoresis (CZE) method has been developed and validated for assaying the aripiprazole (ARP) in tablet dosage form. The separation of ARP from its degradation products and internal standard was achieved using a fused silica capillary column (30.2 cm x 75 μm ID), a background electrolyte containing 6 mmol L−1 ammonium formate buffer (pH 3) with 5% methanol under a potential of 15 kV and detection at 214 nm. The stability indicating ability of the method was investigated by analyzing ARP after being subjected to acidic, alkaline, thermal, photolytic, and oxidative stress conditions, according to ICH guidelines. Design of experiments was used during forced degradation and method optimization. Oxidation was the main degradation pathway among those evaluated. The drug was separated from its oxidative degradation products in less than 4 min. CZE method was linear between 60 – 140 μg mL−1, R2 = 0.9980, precise (intra-day 0.88% and inter-day 1.30%). The average recovery was 100.93 ± 0.77%. This is the first method in the literature for quantification of ARP in the presence of its related degradation products with high separation efficiency, low operation cost and minimum solvent consumption. This method could be helpful in the routine quality control analysis in the pharmaceutical industries with least harmful effect on the environment. CZE is considered an eco-friendly alternative of conventionally HPLC methods.

Chemometric Quality Assessment of Doxylamine Succinate With Its Degradation Product: Implementation of Two Predictive Models on UV-Spectrophotometric Data of Anti-Emetic Binary Mixture.

The combination of pyridoxine hydrochloride (PYR) and doxylamine succinate (DOX) as an antiemetic binary mixture is used to treat nausea and vomiting during pregnancy. Two validated, accurate, and selective chemometric models were developed to assay binary mixture in the presence of DOX oxidative degradation product (DOX DEG) that could be characterized using LC-MS. Partial least squares (PLS) regression and principal component regression (PCR) were selected for the determination of our binary mixture in presence of degradation. To exhibit a training set of 25 mixtures that had various percentages of tested substances in five level 3 variables, an experimental design was chosen. A set of 18 synthetic mixtures in the concentration range 10.0-50.0 μg/mL, 12.00-20.0 μg/mL, and 6.0-30.0 μg/mL for PYR, DOX, and DOX DEG, respectively, were used in the construction of the calibration models.Then set of seven synthetic mixtures with different concentrations were used in the construction of the validation models. In validation samples with low root mean square error of prediction (RMSEP), the suggested models successfully predicted the concentrations of our drugs. The models developed were evaluated by RMSEP calculation, and the values obtained were 0.341, 0.196, and 0.388 for PYR, DOX, and DOX DEG, respectively, using PLS. While using PCR, RMSEP calculation and the values obtained were 0.400, 0.256, and 0.375 for PYR, DOX, and DOX DEG, respectively. The developed models were validated according to ICH strategies. The corresponding methods are suitable to determine PYR and DOX in pure form, pharmaceutical dosage form, and in the presence of DOX DEG product. The study of drug breakdown pathways is very important nowadays, so even in the presence of degradation and extreme spectral overlapping, the suggested PLS and PCR spectrophotometric approaches were able to identify PYR and DOX.

Stability indicating potentiometric method for the determination of palonosetron HCl using two different sensors

This paper presents a novel potentiometric approach for the determination of palonosetron HCl using two sensors; ionophore-free and ionophore-doped ones. The two sensors successfully determined the cited drug in the range of 1 × 10–5–1 × 10–2 M with respective Nernstian slopes of 54.9 ± 0.25 and 59.3 ± 0.16 mV/decade. Incorporating calix[8]arene as an ionophore resulted in a lower detection limit (LOD = 3.1 × 10–6 M) and enhanced selectivity when compared to the ionophore-free sensor (LOD = 7.9 × 10–6 M). This modification was also associated with faster response for the ionophore-doped sensor (response time = 20 s) compared to the ionophore-free one (response time = 30 s). The two sensors showed a stable response over a pH range of 3.0–8.0. They successfully determined palonosetron HCl in presence of its oxidative degradation products. They were also used for direct determination of the drug in commercially available parenteral solution without any interference from other dosage forms’ additives.

Oxidative degradation in pharmaceuticals: Mechanism and stabilization of a spray-dried amorphous drug – A case study

Drug formulations such as spray drying are often required to improve the physicochemical properties and bioavailability of hydrophobic drugs. However, excipients often carry contaminants/ impurities and may also increase moisture levels in solid formulations, which can have detrimental effects on the drugs, including drug degradation and stability. Hence, achieving adequate shelf life of drug products has been among the most challenging issues for pharmaceuticals. Here we report a case study where we systematically studied the oxidative degradation of a pharmaceutical compound GENE-A, spray-dried and dispersed in hydroxypropyl methylcellulose-acetate succinate polymer matrix. Three different oxidative degradation products were observed, and their mechanisms of formation were investigated via forced degradation studies. Finally, we used several antioxidants based on their mechanisms of action to reduce/ prevent the drug degradation process. Propyl gallate alone and in combination with Ethylenediaminetetraacetic acid completely prevented the formation of two degradation products, whereas there was no significant impact observed on the third one. The results showed that both metal chelators and free radical terminators most effectively prevented drug degradation. This study may address some of the key issues that pharmaceutical companies encounter and offer appropriate solutions to counter the oxidative degradation process of pharmaceuticals.

Furthering the understanding of product formation in monoethanolamine degradation: A mechanistic DFT study

A thorough understanding of the product formation originating during degradation of monoethanolamine is crucial to future commercialization of carbon capture plants. Here we report on a series of density functional theory (DFT) calculations outlining chemical pathways for the formation of oxidative degradation products. Fragmentation of monoethanolamine (MEA) radicals is surmountable given standard experimental conditions and can lead to the formation of ethanal, ethanoic acid, ammonia, methylamine, water, formaldehyde, formic acid and imines. Alternatively, the MEA radicals can form hydroperoxides after reaction with oxygen which can subsequently go on to form glycine, glycolic acid and N-(2-hydroxyethyl)glycine (HEGly). Experimentally surmountable routes to the formation of oxazoline, N-(2-hydroxethyl)ethylenediamine (HEEDA), N,N’-bis(2-hydroxyethyl)ethylenediamine (BHEEDA), epoxides, (2-Methylamino)ethanol (MAE), N-(2-hydroxyethyl)imidazole (HEI) and diethanolamine (DEA) are also presented.

Free Radical Chain Reactions and Polyunsaturated Fatty Acids in Brain Lipids.

Polyunsaturated fatty acyl chains (PUFAs) concentrate in the brain and give rise to numerous oxidative chemical degradation products. It is widely assumed that these products are the result of free radical chain reactions, and reactions of this type have been demonstrated in preparations where a single PUFA substrate species predominates. However, it is unclear whether such reactions can occur in the biologically complex milieu of lipid membranes where PUFA substrates are a minority species, and where diverse free radical scavengers or other quenching mechanisms are present. It is of particular interest to know whether they occur in brain, where PUFAs are concentrated and where PUFA oxidation products have been implicated in the pathogenesis of neurodegenerative disorders. To ascertain whether free radical chain reactions can occur in a complex brain lipid mixture, mouse brain lipids were extracted, formed into vesicles, and treated with a fixed number of hydroxyl radicals under conditions wherein the concentrations and types of PUFA-containing phospholipids were varied. Specific phospholipid species in the mixture were assayed by tandem mass spectrometry to quantify the oxidative losses of endogenous PUFA-containing phospholipids. Results reveal crosstalk between the oxidative degradation of ω3 and ω6 PUFAs that can only be explained by the occurrence of free radical chain reactions. These results demonstrate that PUFAs in a complex brain lipid mixture can participate in free radical chain reactions wherein the extent of oxidative degradation is not limited by the number of reactive oxygen species available to initiate such reactions. These reactions may help explain otherwise puzzling in vivo interactions between ω3 and ω6 PUFAs in mouse brain.

Characterization of Oxidative Degradation Product of Canagliflozin by LC-MS/MS

Prior knowledge of chemical stability of drugs directs path for right selection of dosage form, excipients, storage conditions and packaging material. Literature survey revealed that, there are analytical methods reported for quantification and stability indication of Canagliflozin in bulk and formulation. But there is not much information available about the degradation products generated under different stability conditions. With this background, characterization of oxidative degradation product of Canagliflozin was successfully carried out by Liquid Chromatography-Mass Spectrometry (LC-MS/MS) studies. Degradation product was generated by forced degradation, according to International Conference on Harmonization (ICH) guidelines. Degradation product was separated from Canagliflozin by validated reverse phase (RP)-HPLC method using C18 column and Acetonitrile: Water pH 3.0 adjusted with 0.1% formic acid (70: 30, v/v) as mobile phase at a flow rate of 1mL/min. The developed RP-HPLC method was validated for different parameters as per ICH guidelines. The method was found to be linear in a range of 25-225 μg/mL. The developed method was found to be specific, accurate, precise, sensitive and robust. The marketed tablet formulation was analyzed by the developed method and the percent drug content was found to be 100.09 ± 1.96 % w/w. Separated degradation product was characterized by LC-MS/MS studies. From LC-MS/MS data probable structure of the degradation product was interpreted and the mechanism of degradation was proposed. The probable structure of degradation product was proposed as2-(4-Fluorophenyl)-5-({2-methyl-5-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]phenyl}methyl) thiophene-1-one. The mechanism of degradation was proposed by S-oxidation of thiophene ring to form thiophene oxide. This information will help synthetic chemists to design a synthesis scheme for the oxidative degradation product, which can be used as a reference standard for impurity profiling. It is also suggested to protect CN from oxidative conditions for improved stability.

Study of the toxicity of combustion products of polymer materials using chromatomass spectrometry

Introduction. Carrying out studies of the toxicity of combustion products (HCL50) of polymer materials: epoxy glue grade EK-5T and compound ELPLAST-180 ID according to GOST with the additional use of gas chromatography with mass selective detection. Objective. Experimental study of the toxicity of combustion products (HCL50) of polymer materials in various modes of thermal oxidative degradation: epoxy glue grade EK-5T and compound ELPLAST-180 ID, as well as a survey mass spectrometric analysis of products of thermal oxidative degradation. Material and methods. The studies were carried out in accordance with GOST 12.1.044-89. Equipment: “Toxicity” unit, “Infracar M2.01” gas analyzer, Focus GC chromato-mass-spectrometric instrumental complex with DSQ II mass spectrometer (Thermo Scientific, USA), Nova Medical Stat Profile automatic analyzer of blood gases, electrolytes and oximetry Model CCX (USA). Blood sampling was carried out in capillaries “Stat Profile Critical Care Express Capillary Tube 230 µL with Na Heparin” LOT 107669, CO2 chamber. Results. In the course of studying the products of outgassing of polymer materials using an exposure chamber and a gas chromatomass spectrometer, a significant increase in toxicity (4.8 times) of a mixture of chemicals released from epoxy glue EK-5T during the transition from thermal-oxidative decomposition (smoldering) to flame combustion was established. The toxicity index of the combustion products of the ELPLAST-180 ID compound under the same conditions increases by 1.8 times. A linear dependence of the percentage of lethality of laboratory animals on the integral indicator of the toxicity of combustion products has been established. Limitations. Studies of the toxicity of combustion products were carried out on non-metallic materials: epoxy glue EK-5T, compound ELPLAST-180 ID. These materials are planned to be used in hermetically sealed objects of the Navy. Conclusion. The expediency of using gas chromatography-mass spectrometry for assessing the combined effect of combustion products is shown.

Eco-friendly stability-indicating HPTLC micro-determination of the first FDA approved SARS-CoV-2 antiviral prodrug Remdesivir: Study of degradation kinetics and structural elucidation of the degradants using HPTLC-MS

The worldwide spread coronavirus (covid-19) pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents a global health crisis. The world was forced to face a great challenge to control and overcome this health disaster through various containment measures including efficient vaccination side by side with effective medication. Remdesivir (RMD) is the first FDA approved antiviral agent for treatment of covid-19 pandemic and hence regarded as the first-in-class medication of this highly contagious respiratory disease. The current study represents the first stability indicating HPTLC method for the estimation of RMD in bulk form and pharmaceutical formulation. The method employed TLC silica gel aluminum plates 60 F254 as stationary phase and green mobile phase composed of ethyl acetate and ethanol (96: 4, v/v) with densitometric detection at 245 nm. Comprehensive validation of the adopted method was accomplished according to the ICH guidelines regarding linearity, ranges, detection and quantification limits, precision, accuracy and robustness. The developed method offered a neat separation of the drug in presence of pharmaceutical excipients as well as in presence of acidic, alkaline, neutral hydrolytic, oxidative and photolytic degradants. Additionally, structural elucidation of alkaline and hydrolytic oxidation degradation products was carried out using HPTLC-MS. Furthermore, for the first time the acidic and alkaline degradation kinetics of RMD were studied and its degradation rate constants and half-lives were calculated. Moreover, greenness appraisal of the developed method as well as comparison with previously published stability indicating HPLC methods were performed using analytical Eco-scale, GAPI and AGREE metrics.

Structural elucidation of major degradation products of milbemycin oxime drug substance using LC-MS and NMR

Milbemycin oxime (MO) drug substance is a 16-membered macrocyclic lactone that exhibits a broad spectrum of biological activity and high potency towards parasites. In this study, a comprehensive forced degradation study was carried out on MO drug substance to identify and characterize its major degradation products (DPs). MO drug substance was subjected to acid, base, oxidation (H2O2), heat (solid and solution state), and photolytic (solid and solution state) stress degradation as per the ICH guidelines. Chromatographic separation of the drug substance (MO A3 and MO A4) and its DPs was achieved using a gradient elution on a HALO C18 column (100 × 4.6 mm, 2.7 µm). Mobile phase A consisted of water/acetonitrile (60/40, v/v) and mobile phase B consisted of ethanol/isopropanol (50/50, v/v). A total of twelve major DPs were observed for MO drug substance under various stress conditions. These DPs were further identified and characterized using liquid chromatography-high resolution mass spectrometry and comparison of their fragmentation profile with MO A4 and MO A3 using tandem mass spectrometry. Of these, H2O2 induced oxidative degradation product (3,4-dihydroperoxide MO A4) was isolated using semi-preparative HPLC and characterized by comparison of its nuclear magnetic resonance spectroscopy data with MO A4. The proposed structures of the DPs have been rationalized by appropriate degradation pathways for MO A4 and MO A3.

Characterization and in‐silico toxicity prediction of the oxidative degradation products of Pimozide

AbstractThe investigation's objective was to access the stability of the drug substance Pimozide under the stress conditions specified in the International Conference on Harmonization Q1A(R2) guideline and to separate, identify, and characterize the degradation products by using liquid chromatography‐tandem mass spectrometry studies without isolating them from the reaction mixture. It was observed that the drug was susceptible to oxidative degradation (15% hydrogen peroxide, 48 h, room temperature) forming four novel degradation products while being stable under hydrolytic, Photolytic, and thermal conditions. The separation of the drug and the degradation products was achieved with good resolution on a Phenomenex C18 column (150 mm × 4.6 mm, 5 µm) using gradient elution. The fragmentation pattern constructed from the liquid chromatography‐quadrupole‐time of flight mass spectrometry data was used for structural characterization of the degradation products. Lastly, the in‐silico absorption, distribution, metabolism, excretion, and toxicity properties prediction was performed by using in‐silico tools like the pKCSM webserver, ToxTree, and OSIRIS property explorer. The primary screening through the pKCSM webserver exposed the hepatoxic and the mutagenic potential of Pimozide, 1‐(1‐(4‐(4‐fluorophenyl)‐4‐phenylbutyl) piperidin‐4‐yl)‐1,3‐dihydro‐2H‐benzo[d]imidazol‐2‐one (degradation product 3) and 1‐(4,4‐bis(4‐fluorophenyl)butyl)‐4‐(2‐oxo‐2,3‐dihydro‐1H‐benzo[d]imidazol‐1‐yl)piperidine 1‐oxide (degradation product 5) whereas, 1‐(1‐(4,4‐diphenylbutyl) piperidin‐4‐yl)‐2,3‐dihydro‐1H‐benzo[d]imidazol‐2‐ol (degradation product 1) was predicted to only possess mutagenic potential. Secondary screening for mutagenicity was done by using ToxTree and OSIRIS property explorer.