Covalent organic frameworks: spotlight on applications in the pharmaceutical arena.

Covalent organic frameworks (COFs) have much potential in the field of analytical separation research due to their distinctive characteristics, including easy modification, low densities, large specific surface areas and permanent porosity. This article provides a historical overview of the synthesis and broad perspectives on the applications of COFs. The use of COF-based membranes in gas separation, water treatment (desalination, heavy metals and dye removal), membrane filtration, photoconduction, sensing and fuel cells is also covered. However, these COFs also demonstrate great promise as solid-phase extraction sorbents and solid-phase microextraction coatings. In addition to various separation applications, this work aims to highlight important advancements in the synthesis of COFs for chiral and isomeric compounds.

Discerning the stability behaviour of mavacamten availing liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy: In silico toxicity and mutagenicity prediction of degradation products.

The present study aimed to separate, identify, and characterise the degradation products formed when mavacamten is exposed to stress degradation as well as the stability of the drug in various environments and also to understand its degradation chemistry. Prediction of in silico toxicity and mutagenicity was aimed at the observed degradation products. Stress degradation along with stability studies and degradation kinetics were performed on mavacamten, and separation of degradation products was carried out by high-performance liquid chromatography. Tandem mass spectrometry studies were executed to characterise the structures of degradation products using product ion fragments. Orthogonally, nuclear magnetic resonance experiments were conducted to elucidate the structures having ambiguity in characterising them. Deductive Estimation of Risk from Existing Knowledge and Structure Activity Relationship Analysis using Hypotheses software were used to establish in silico toxicity and mutagenic profiles of mavacamten and its degradation products. Two degradation products of mavacamten found in acidic hydrolytic stress conditions were separated, identified, characterised, and proposed as 1-isopropylpyrimidine-2,4,6(1H,3H,5H)-trione and 1-phenylethanamine. Mavacamten was found to be stable under different pH and gastrointestinal conditions. The degradation kinetics of mavacamten under 1 N acidic condition followed zero-order kinetics, and it was degraded completely within 6 h. In silico toxicity and mutagenicity studies revealed that 1-phenylethanamine can be a skin sensitiser. A high-performance liquid chromatography method was developed for the separation of degradation products of mavacamten and characterised by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance. During the manufacturing and storage of drug product, precautions need to be taken when dealing with acidic solutions as the drug is prone to hydrolysis in acidic conditions. The formation of 1-phenylethanamine under these conditions is to be monitored as it is a skin sensitiser.

LC-HRMS and NMR studies for the characterization of degradation impurities of ubrogepant along with the in silico approaches for the prediction of degradation and toxicity.

Ubrogepant is the first oral calcitonin gene-related peptide (CGRP) receptor antagonist which is used for the acute treatment of migraine in adults. The present study employs liquid chromatography-high resolution mass spectrometry (LC-HRMS) and nuclear magnetic resonance spectroscopy (NMR) techniques for the identification and characterization of degradation impurities of ubrogepant. The forced degradation study of ubrogepant was performed as per the International Council for Harmonisation (ICH) Q1A and Q1B guidelines. The in silico degradation profile of ubrogepant was predicted by Zeneth. It was observed that ubrogepant was labile to acidic hydrolysis, basic hydrolysis, and oxidative degradation conditions (H2O2), although it was stable in neutral hydrolysis and photolytic (UV light and visible light) conditions. Eight degradation impurities were formed, which were separated on reversed-phase HPLC with a gradient program on an InertSustain C8 column (4.6 × 250 mm, 5 µm) using 10 mM ammonium formate (pH unadjusted) and acetonitrile as the mobile phase. The structures of all the degradation impurities were characterized using the exact masses obtained from the HRMS/MS. Further, NMR studies were conducted on two major degradation impurities (UB-4 and UB-7). A plausible mechanism was proposed to support the structures of all the degradation impurities of UBR. In silico toxicity and mutagenicity assessment were done by DEREK Nexus, SARAH Nexus, and ProTox-II.

In vivo and in vitro metabolite profiling of nirmatrelvir using LC-Q-ToF-MS/MS along with the in silico approaches for prediction of metabolites and their toxicity.

Nirmatrelvir (NRV), a 3C-like protease or Mpro inhibitor of SARS-CoV-2, is used for the treatment of COVID-19 in adult and paediatric patients. The present study was accomplished to investigate the comprehensive metabolic fate of NRV using in vitro and in vivo models. The in vitro models used for the study were microsomes (human liver microsomes, rat liver microsomes, mouse liver microsomes) and S9 fractions (human liver S9 fractions and rat liver S9 fractions) with the appropriate cofactors, whereas Sprague-Dawley rats were used as the in vivo models. Nirmatrelvir was administered orally to Sprague-Dawley rats, which was followed by the collection of urine, faeces and blood at pre-determined time intervals. Protein precipitation was used as the sample preparation method for all the samples. The samples were then analysed by liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-Q-ToF-MS/MS) using an Acquity BEH C18 column with 0.1% formic acid and acetonitrile as the mobile phase. Four metabolites were found to be novel, which were formed via amide hydrolysis, oxidation and hydroxylation. Furthermore, an in silico analysis was performed using Meteor Nexus software to predict the probable metabolic changes of NRV. The toxicity and mutagenicity of NRV and its metabolites were also determined using DEREK Nexus and SARAH Nexus.

Monophasic coamorphous sulpiride: a leap in physicochemical attributes and dual inhibition of GlyT1 and P-glycoprotein, supported by experimental and computational insights.

Study aimed to design and development of a supramolecular formulation of sulpiride (SUL) to enhance its solubility, dissolution and permeability by targeting a novel GlyT1 inhibition mechanism. SUL is commonly used to treat gastric and duodenal ulcers, migraine, anti-emetic, anti-depressive and anti-dyspeptic conditions. Additionally, Naringin (NARI) was incorporated as a co-former to enhance the drug's intestinal permeability by targeting P-glycoprotein (P-gp) efflux inhibition. NARI, a flavonoid has diverse biological activities, including anti-apoptotic, anti-oxidant, and anti-inflammatory properties. This study aims to design and develop a supramolecular formulation of SUL with NARI to enhance its solubility, dissolution, and permeability by targeting a novel GlyT1 inhibition mechanism, extensive experimental characterization was performed using solid-state experimental techniques in conjunction with a computational approach. This approach included quantum mechanics-based molecular dynamics (MD) simulation and density functional theory (DFT) studies to investigate intermolecular interactions, phase transformation and various electronic structure-based properties. The findings of the miscibility study, radial distribution function (RDF) analysis, quantitative simulations of hydrogen/π-π bond interactions and geometry optimization aided in comprehending the coamorphization aspects of SUL-NARI Supramolecular systems. Molecular docking and MD simulation were performed for detailed binding affinity assessment and target validation. The solubility, dissolution and ex-vivo permeability studies demonstrated significant improvements with 31.88-fold, 9.13-fold and 1.83-fold increments, respectively. Furthermore, biological assessments revealed superior neuroprotective effects in the SUL-NARI coamorphous system compared to pure SUL. In conclusion, this study highlights the advantages of a drug-nutraceutical supramolecular formulation for improving the solubility and permeability of SUL, targeting novel schizophrenia treatment approaches through combined computational and experimental analyses.Communicated by Ramaswamy H. Sarma.

In Silico Tools to Thaw the Complexity of the Data: Revolutionizing Drug Research in Drug Metabolism, Pharmacokinetics and Toxicity Prediction.

In silico tool is the flourishing pathway for Researchers and budding chemists to strain the analytical data in a snapshot. Traditionally, drug research has heavily relied on labor-intensive experiments, often limited by time, cost, and ethical constraints. In silico tools have paved the way for more efficient and cost-effective drug development processes. By employing advanced computational algorithms, these tools can screen large libraries of compounds, identifying potential toxicities and prioritizing safer drug candidates for further investigation. Integrating in silico tools into the drug research pipeline has significantly accelerated the drug discovery process, facilitating early-stage decision-making and reducing the reliance on resource-intensive experimentation. Moreover, these tools can potentially minimize the need for animal testing, promoting the principles of the 3Rs (reduction, refinement, and replacement) in animal research. This paper highlights the immense potential of in silico tools in revolutionizing drug research. By leveraging computational models to predict drug metabolism, pharmacokinetics, and toxicity. Researchers can make informed decisions and prioritize the most promising drug candidates for further investigation. The synchronicity of In silico tools in this article on trending topics is insightful and will play an increasingly integral role in expediting drug development.

Forced degradation study of baricitinib and structural characterization of its degradation impurities by high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy.

RATIONALE: Baricitinib (BARI), an inhibitor of Janus kinases 1 and 2 (JAK 1/2), is used for the treatment of rheumatoid arthritis and COVID-19. The present study focuses on establishing the forced degradation behavior of BARI under different degradation conditions (hydrolysis, oxidation, and photolysis) following International Council for Harmonization (ICH) guidelines of Q1A (R2)-Stability testing of new drug substances and products and Q1B-Photostability testing of new drug substances and products. This study helps in monitoring the quality and safety of BARI and its product development. METHODS: Prior to conducting the study, the in silico degradation profile of BARI was predicted by Zeneth. Reversed-phase high-performance liquid chromatography employing a gradient program was used for the identification and separation of degradation impurities with an InertSustain C8 column (4.6 × 250 mm, 5 µm). The mobile phases used were 10 mM ammonium formate (pH 2.89) and acetonitrile. High-resolution mass spectrometry (HRMS) was used for the structural elucidation of the degradation impurities. RESULTS: BARI was labile to hydrolytic (acidic, basic, and neutral) and photolytic degradation conditions which yielded 10 new degradation impurities and it was stable under oxidative (H2 O2 ) conditions. The separated degradation impurities were characterized by HRMS and the respective degradation pathways were proposed. The generated information helped to propose a mechanism for the formation of the degradation impurities. Additionally, one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy were used for the characterization of two major degradation impurities. CONCLUSION: The forced degradation study of BARI was carried out in accordance with ICH Q1A and Q1B guidelines, which resulted in the formation of 10 new degradation impurities. In our analysis, three degradation impurities were matching with the Zeneth predictions. In silico tools, DEREK Nexus® and SARAH Nexus®, were used for predicting the toxicity and mutagenicity of BARI and its degradation impurities. Overall, this study sheds light on BARI's safety monitoring and storage circumstances.

Structural characterization and in silico toxicity prediction of degradation impurities of roxadustat.

Roxadustat is the first drug approved for anemia due to chronic kidney disease. Drug degradation profile is very crucial for assessing the quality and safety of the drug substances and their formulations. Forced degradation studies are conducted for quick prediction of drug degradation products. Forced degradation of roxadustat was carried out as per ICH guidelines, and nine degradation products (DPs) were observed. These DPs (DP-1 to DP-9) were separated using the reverse phase HPLC gradient method with an XBridge column (250 mm × 4.6 mm, 5 µm). The mobile phase consisted of 0.1% formic acid (solvent A) and acetonitrile (solvent B) at a flow rate of 1.0 ml/min. The chemical structures of all the DPs were proposed by using LC-Q-TOF/MS. DP-4 and DP-5, the two major degradation impurities, were isolated, and NMR was used to confirm their chemical structures. Based on our experiments, the roxadustat was found stable to thermal degradation in solid state and oxidative conditions. However, it was unstable in acidic, basic, and photolytic conditions. A very remarkable observation was made about DP-4 impurity. DP-4 was generated as a common degradation impurity in alkaline hydrolysis, neutral hydrolysis as well as photolysis conditions. DP-4 has a similar molecular mass to roxadustat but is structurally different. DP-4 is chemically, (1a-methyl-6-oxo-3-phenoxy-1,1a,6,6a-tetrahydroindeno [1,2-b] aziridine-6a-carbonyl) glycine. In silico toxicity study was conducted using Dereck software to gain the best knowledge of the drug and its degradation products towards carcinogenicity, mutagenicity, teratogenicity, and skin sensitivity. A further study using molecular docking confirmed the potential interaction of DPs with proteins responsible for toxicity. DP-4 shows a toxicity alert due to the presence of aziridine moiety.

A critical review of Roxadustat formulations, solid state studies, and analytical methodology.

This review aims to collate information about the analytical methodologies, bioanalytical methodologies, pharmaceutical formulations, solid-state studies, and the current and future market scenario for a relatively new class of drugs, Roxadustat. Roxadustat is a hypoxia-inducible factor propyl hydroxylase inhibitor that significantly increases blood hemoglobin via the action of transcriptional activator HIF. As the molecule has a promising role in stimulating erythropoiesis, it is considered an ideal therapeutic agent for patients with anemia. In the current review, an attempt has been made to compile the pharmacological, pharmacokinetic, and pharmacodynamic characteristics of Roxadustat and systematically present product development data. This drug has several polymorphs of cocrystal, co-former, and salt, which have been explained in detail in the current work. The comprehensive review summarizes all the chromatographic methods and is presented in table form. This review has extensively covered Liquid chromatography-tandem mass spectrometry methods used to analyze Roxadustat in the biological matrix. The literature needs more data on forced degradation study, impurity profiling, gas chromatography, analytical methods for assay, dissolution, and different formulation aspects of Roxadustat.

Insight into in silico prediction and chemical degradation study of osimertinib mesylate by LC-HRMS and NMR: Investigation of a typical case of alkaline pH-mediated oxidative degradation product.

Osimertinib mesylate is a third-generation epidermal growth factor receptor tyrosine kinase inhibitor used to treat nonsmall-cell lung cancer. The objective was to understand in silico prediction and chemical-based stress testing of the osimertinib mesylate. A total of eight degradation products (DPs) were formed under chemical stress testing. An in silico tool viz., Zeneth predicted a higher percentage of DPs. The separation of all the DPs was achieved using reversed phase high-performance liquid chromatography, employing X-Bridge C18 column with ammonium acetate (pH adjusted to 7.50 with ammonia) and acetonitrile as mobile phase. The overall results showed it underwent significant degradation in acidic, alkaline, and oxidative conditions. In rest of the conditions, osimertinib mesylate was found to be stable or slight degradation was observed in photolytic condition. The structure of DPs was elucidated with a comparison of data generated from high-resolution mass spectrometry (HRMS) of osimertinib mesylate and its degradation products. To confirm the unambiguous regioisomers, one-dimensional (1D) and two-dimentional (2D) nuclear magnetic resonance studies were performed. Furthermore, the N-oxide position was assigned for the first time using the Meisenheimer rearrangement reaction in atmospheric pressure chemical ionization mode. Interestingly, an unusual reaction of DP2 formation was observed at alkaline conditions. In silico tools such as DEREK and Sarah predicted osimertinib mesylate and most of the DPs found to be structural alert for mutagenicity.

LC-HRMS and NMR studies for characterization of forced degradation impurities of ponatinib, a tyrosine kinase inhibitor, insights into in-silico degradation and toxicity profiles.

The degradation profile of ponatinib was established during the present study by exposing it to various stress conditions. In-silico degradation pattern of ponatinib was outlined by using Zeneth software. Five degradation impurities were formed during the stress testing of ponatinib. High performance liquid chromatographic method was developed to separate these degradation impurities which includes ammonium acetate of pH 4.75 (A) and methanol (B) as mobile phase in gradient elution mode and Waters Reliant C18 (4.6 × 250 mm, 5 µm) column as stationary phase. Optimised flow rate, injection volume and detection wavelength of the HPLC method were 1.0 mL/min, 10 µL and 254 nm, respectively. Chemical structures of degradation impurities were proposed by high resolution mass spectrometry further, major degradation products were isolated, enriched and investigated thoroughly with the aid of nuclear magnetic resonance spectroscopy studies. The degradation impurities were identified as 4-aminophthalaldehyde (DP 1), 4-((4-methylpiperazin-1-yl)methyl)- 3-(trifluoromethyl) benzenamine (DP 2), 3-(2-(imidazo[1,2-b]pyridazin-3-yl)acetyl)- 4-methylbenzoic acid (DP 3), 3-(2-(imidazo[1,2-b]pyridazin-3-yl)ethynyl)- 4-methylbenzoic acid (DP 4) and N-oxide impurity (DP 5) which are new and were not reported in the literature till date. Additionally, toxicity and mutagenicity profiles of ponatinib and its degradation impurities were predicted in-silico by using DEREK and SARAH software. This whole study gives meaningful insights about chemical stability of ponatinib which is useful in its drug development lifecycle.

Anxiolytic- and antidepressant-like effects of Bacillus coagulans Unique IS-2 mediate via reshaping of microbiome gut-brain axis in rats.

BACKGROUND: Due to the rising cases of treatment-refractory affective disorders, the discovery of newer therapeutic approaches is needed. In recent times, probiotics have garnered notable attention in managing stress-related disorders. Herein, we examined the effect of Bacillus coagulans Unique IS-2® probiotic on anxiety- and depression-like phenotypes employing maternal separation (MS) and chronic-unpredictable mild stress (CUMS) model in rats. METHODS: Both male and female Sprague-Dawley rats were subjected to MS + CUMS. Probiotic treatment was provided for 6 weeks via drinking water. Anxiety- and depression-like phenotypes were assessed using sucrose-preference test (SPT), forced-swimming test (FST), elevated-plus maze test (EPM), and open-field test (OFT). Blood, brain, intestine, and fecal samples were obtained for biochemical and molecular studies. RESULTS: Stress-exposed rats drank less sucrose solution, showed increased passivity, and explored less in open-arms in SPT, FST, and EPM, respectively. These stress-generated neurobehavioral aberrations were alleviated by 6-week of Bacillus coagulans Unique IS-2 treatment. The overall locomotor activity in OFT remained unchanged. The decreased levels of BDNF and serotonin and increased levels of C-reactive protein, TNF-α, IL-1ß, and dopamine, in the hippocampus and/or frontal cortex of stress-exposed rats were reversed following probiotic treatment. Administration of probiotic also restored the systemic levels of L-tryptophan, L-kynurenine, kynurenic-acid, and 3-hydroxyanthranilic acid, villi/crypt ratio, goblet-cell count, Firmicutes to Bacteroides ratio, and levels of acetate, propionate, and butyrate in fecal samples. These results indicate remodeling of the microbiome gut-brain axis in Bacillus coagulans Unique IS-2 recipient rats. However, protein levels of doublecortin, GFAP, and zona occludens in the hippocampus and occludin-immunoreactivity in the intestine remained unchanged. No prominent sex-specific changes were noted. CONCLUSION: Anxiolytic- and antidepressant-like effects of Bacillus coagulans Unique IS-2 in MS + CUMS rat model may be mediated via reshaping the microbiome gut-brain axis.

Characterization of potential degradation products of brexpiprazole by liquid chromatography/quadrupole-time-of-flight mass spectrometry and nuclear magnetic resonance, and prediction of their physicochemical properties by ADMET Predictor™.

RATIONALE: Brexpiprazole (BRZ) was subjected to hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress degradation in solutions prepared in a mixture of acetonitrile-water (70:30 v/v). The oxidative study was additionally done in methanol-buffer mixture at pH 3, 7 and 11. Also, compatibility of the drug with selected excipients was investigated in the solid state. Additionally, physicochemical and ADMET properties of BRZ and its degradation products (DPs) were predicted using ADMET Predictor™ software. It provides the conditions for quality control of BRZ and its derivatives during manufacturing, processing and storage conditions. METHODS: The formed DPs were separated from the drug and among themselves on a C-18 column utilizing mobile phase composed of methanol and ammonium formate buffer (10mM, pH 4.0), which was run in a gradient mode. Characterization of DPs was carried out by first establishing the mass fragmentation pathway of the drug based on its liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/Q-TOF-MS) data, followed by LC/Q-TOF-MS studies of DPs. Three DPs were isolated and, along with the drug, they were subjected to 1D (1 H, 13 C and DEPT-135) and 2D (COSY and HSQC) NMR studies for confirmation of their structures. RESULTS: BRZ was observed to be susceptible to hydrolytic (neutral, acid and alkali), photolytic and oxidative degradation conditions; it was stable on thermal exposure. A total of 12 DPs (BRZ-1 to BRZ-12) were formed in solution state. Mechanisms of BRZ degradation were postulated. CONCLUSIONS: The extent of degradation of BRZ in different stress conditions highlights that stability of BRZ in drug formulations can be improved (i) by using excipients that can impart a low-pH microenvironment, (ii) by addition of antioxidants and (iii) through protection from light.

Involvement of Microbiome Gut-Brain Axis in Neuroprotective Effect of Quercetin in Mouse Model of Repeated Mild Traumatic Brain Injury.

Repeated mild traumatic brain injury (rmTBI) poses adversity in the form of neurological deficits. The ignition of long-term neurological aberrations post-TBI is appended with the microbiota gut-brain axis perturbation. Herein, we examined whether quercetin, which is anti-inflammatory and antioxidant flavonoid, serves as a prebiotic and modifies the compromised microbiome gut-brain axis in rmTBI mouse model. Male C57BL/6 mice were subjected to rmTBI for 7 times. The quercetin (50 mg/kg) was administered peroral from the day1 of first injury till 7 days post-injury. The neurobehavioral assessments were performed using return of righting reflex (ROR), rotarod, forced swimming test (FST), elevated zero maze (EZM), novel object recognition test (NORT), and Y-maze. Mice fecal samples, brains, and intestines were collected for molecular studies. Mice underwent rmTBI showed significant neurological deficits in ROR and rotarod test and also exhibited long-term neuropsychiatric aberrations like anxiety- and depression-like phenotypes, and cognitive deficits in EZM, FST, and Y-maze assays, respectively. Repeated peroral administration of quercetin ameliorated these neuropsychiatric problems. Quercetin treatment also restored the increased expression of GFAP and decreased expression of occludin and doublecortin in the frontal cortex and hippocampus of rmTBI mice. The altered levels of acetate and propionate, and microbial phylum abundance in fecal samples were also normalized in the quercetin-treated group. We also noted an improved intestinal permeability indicated by reduced villi rupture, blunting, and mucosal thinning in quercetin-treated mice. We suggest that the neuroprotective effect of quercetin may be mediated via remodeling of the microbiome gut-brain axis in rmTBI mouse model.

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 (10 mM, 4.8 pH, acetic acid) and acetonitrile. The flow rate was maintained at 1 ml 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.

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.

Ru(II)-Catalyzed Regioselective C-N Bond Formation on Benzothiazoles Employing Acyl Azide as an Amidating Agent.

A Ru(II)-catalyzed regioselective direct ortho-amidation of 2-aryl benzo[d]thiazoles employing acyl azides as a nitrogen source has been accomplished. This approach utilizes the efficiency of benzothiazole as a directing group and the role of acyl azide as an effective amidating agent toward C-N bond formation, thereby evading the general Curtius rearrangement. The protocol highlights significant functional group tolerance, single-step, and external oxidant-free conditions, with the release of only innocuous molecular nitrogen as the byproduct. The reaction mechanism and the intermediates associated with this selective Ru-catalyzed reaction have been investigated using ESI-MS. The protocol also aided in the construction of ortho-amidated ß-carbolines, unveiling another class of fluorescent molecules.

Stress degradation study on entrectinib and characterization of its degradation products using HRMS and NMR.

Entrectinib is a potent inhibitor of receptor tyrosine kinases and anaplastic lymphoma kinase. It is designated as an orphan drug. There exists no report of comprehensive degradation profiling of the drug in the literature. Therefore, the present study focused on establishment of its stress degradation chemistry under hydrolytic (acidic, alkaline, neutral), oxidative (H2O2), photolytic and thermal conditions. For the purpose, the stressed solutions were subjected to HPLC studies on a C8 column by employing a gradient elution method, in which acetonitrile and 10 mM ammonium acetate were used as the mobile phase components. The results showed that entrectinib was labile to alkaline, H2O2, and photoneutral conditions in the solution state. The drug proved to be stable under acidic, solid-state photolytic, and thermal conditions. A total of sixteen degradation products were formed, which were characterized with the help of high resolution mass spectrometry, and in one case additional help was taken of 1D and -2D NMR data. The knowledge of the structures of the degradation products helped in establishment of degradation pathway of the drug and the involved mechanisms. Also, the toxicity profile of the drug and its degradation products was predicted using ADMET Predictor™ software, which indicated mutagenic potential of atleast five degradation products.

Cytochrome P450 enzymes: a review on drug metabolizing enzyme inhibition studies in drug discovery and development.

Assessment of drug candidate's potential to inhibit cytochrome P450 (CYP) enzymes remains crucial in pharmaceutical drug discovery and development. Both direct and time-dependent inhibition of drug metabolizing CYP enzymes by the concomitant administered drug is the leading cause of drug-drug interactions (DDIs), resulting in the increased toxicity of the victim drug. In this context, pharmaceutical companies have grown increasingly diligent in limiting CYP inhibition liabilities of drug candidates in the early stages and examining risk assessments throughout the drug development process. This review discusses different strategies and decision-making processes for assessing the drug-drug interaction risks by enzyme inhibition and lays particular emphasis on in vitro study designs and interpretation of CYP inhibition data in a stage-appropriate context.