Methicillin-Resistant Staphylococcus aureus Infection and its Health Perspective: A Review.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a potential threat globally since it is associated with high morbidity and mortality. In addition, the ability of MRSA to develop resistance and adapt to various environments makes it exceptional from other bacterial strains. Effective management is best determined by the site of infection. OBJECTIVES: This study aims to summarize and assess the epidemiology of MRSA, resistance, detection of MRSA in humans, animals, and food products, treatment employed, and combination therapy. METHODS: For the present review, we collected data from PubMed, Embase, Web of Science, BioMed Central, Medline, Encyclopedia of Life Sciences, Scopus, Cochrane Library, and ScienceDirect that report the epidemiology of MRSA, drug resistance in MRSA, spread of MRSA infection, diagnosis of infection, existing and emerging remedies of MRSA infections. Collected data were analyzed and represented in this article with the help of Figures and Tables. RESULTS: S. aureus resistance to vancomycin is because of genetic adaptation and also due to the widespread and indiscriminate use of antibiotics in the treatment of MRSA infection. Specifically, infections related to vancomycin-resistant S. aureus are life-threatening and difficult to treat. MRSA epidemiology with the recognition of community-acquired-MRSA transmission between livestock and humans is also reported and is alarming. Multiple studies suggested that early detection of MRSA colonization and elimination of carriage can help reduce the risk of subsequent infection. Specifically, PCR-based screening from different body sites offers the highest overall sensitivity for the detection of MRSA carriage. CONCLUSION: Screening novel mutants and methods of transmission in each environment will assist in managing MRSA. Further, effective MRSA control in all clinical setups is required with the avoidance of uncontrolled antibiotic usage.

The Impact of Paediatric Obesity on Drug Pharmacokinetics: A Virtual Clinical Trials Case Study with Amlodipine.

The incidence of paediatric obesity continues to rise worldwide and contributes to a range of diseases including cardiovascular disease. Obesity in children has been shown to impact upon the plasma concentrations of various compounds, including amlodipine. Nonetheless, information on the influence of obesity on amlodipine pharmacokinetics and the need for dose adjustment has not been studied previously. This study applied the physiologically based pharmacokinetic modelling and established a paediatric obesity population to assess the impact of obesity on amlodipine pharmacokinetics in children and explore the possible dose adjustments required to reach the same plasma concentration as non-obese paediatrics. The difference in predicted maximum concentration (Cmax) and area under the curve (AUC) were significant between children with and without obesity across the age group 2 to 18 years old when a fixed-dose regimen was used. On the contrary, a weight-based dose regimen showed no difference in Cmax between obese and non-obese from 2 to 9 years old. Thus, when a fixed-dose regimen is to be administered, a 1.25- to 1.5-fold increase in dose is required in obese children to achieve the same Cmax concentration as non-obese children, specifically for children aged 5 years and above.

Single administration vaccines: delivery challenges, in vivo performance, and translational considerations.

INTRODUCTION: With a limited global supply of vaccines and an increasing vaccine hesitancy, improving vaccination coverage has become a priority. Current vaccination regimes require multiple doses to be administered in a defined schedule where missed doses may lead to incomplete vaccine coverage and failure of immunization programmes. As such, there is an ever-increasing demand to convert multi-dose injectable vaccines into single-dose formats, often called single administration vaccines (SAVs). AREAS COVERED: This review summarizes recent developments in the field of SAVs, with a focus on pulsatile or controlled-release formulations. It will identify the technical challenges, translational as well as commercial barriers to SAVs development. Furthermore, the progress of SAV formulations for hepatitis B and polio vaccines will be reviewed thoroughly as case studies, with a focus on the development challenges and the preclinical immunogenicity/reactogenicity data. EXPERT OPINION: Despite the efforts to develop SAVs, few attempts have advanced to Phase-I trials. Considering the SAV development journey and bottlenecks, including commercial barriers from the early stages, may overcome some of the hurdles around the technology. The renewed global focus on vaccines since the COVID-19 pandemic could facilitate development of a new generation of technologies for pandemic preparedness including strategies for SAVs.

Virtual Clinical Trials Guided Design of an Age-Appropriate Formulation and Dosing Strategy of Nifedipine for Paediatric Use.

The rapid onset of action of nifedipine causes a precipitous reduction in blood pressure leading to adverse effects associated with reflex sympathetic nervous system (SNS) activation, including tachycardia and worsening myocardial and cerebrovascular ischemia. As a result, short acting nifedipine preparations are not recommended. However, importantly, there are no modified release preparations of nifedipine authorised for paediatric use, and hence a paucity of clinical studies reporting pharmacokinetics data in paediatrics. Pharmacokinetic parameters may differ significantly between children and adults due to anatomical and physiological differences, often resulting in sub therapeutic and/or toxic plasma concentrations of medication. However, in the field of paediatric pharmacokinetics, the use of pharmacokinetic modelling, particularly physiological-based pharmacokinetics (PBPK), has revolutionised the ability to extrapolate drug pharmacokinetics across age groups, allowing for pragmatic determination of paediatric plasma concentrations to support drug licensing and clinical dosing. In order to pragmatically assess the translation of resultant dissolution profiles to the paediatric populations, virtual clinical trials simulations were conducted. In the context of formulation development, the use of PBPK modelling allowed the determination of optimised formulations that achieved plasma concentrations within the target therapeutic window throughout the dosing strategy. A 5 mg sustained release mini-tablet was successfully developed with the duration of release extending over 24 h and an informed optimised dosing strategy of 450 µg/kg twice daily. The resulting formulation provides flexible dosing opportunities, improves patient adherence by reducing frequent administration burden and enhances patient safety profiles by maintaining efficacious levels of consistent drug plasma levels over a sustained period of time.

Revisiting the South Indian Traditional Plants against Several Targets of SARS-CoV-2 - An in silico Approach.

BACKGROUND: The south Indian Telugu states will celebrate a new year called 'Ugadi' which is a south Indian traditional festival. The ingredients used in ugadi pachadi have often also been used in food as well as traditional Ayurveda and Siddha medicinal preparations. Coronaviruses (CoVs) are a diverse family of enveloped positive-sense single-stranded RNA viruses which can infect humans and have the potential to cause large-scale outbreaks. OBJECTIVE: Considering the benefits of ugadi pachadi, we investigated the binding modes of various phytochemical constituents reported from its ingredients against five targets of SARS-CoV-2. METHODS: Flexible-ligand docking simulations were achieved through AutoDock version 1.5.6. Following 50ns of molecular dynamics simulation using GROMACS 2018.1 software and binding free energy (ΔGbind) of the protein-ligand complexes were calculated using the g_mmpbsa tool. ADME prediction was done using Qikprop of Schrodinger. RESULTS: From the molecular docking and MM/PBSA results compound Eriodictin exhibited the highest binding energy when complexed with nucleocapsid N protein (6M3M) (-6.8 kcal/mol, - 82.46 kJ/mol), bound SARS-CoV-2-hACE2 complex (6M0J) (-7.4 kcal/mol, -71.10 kJ/mol) and Mpro (6XR3) (-8.6 kcal/mol, -140.21 kJ/mol). Van der Waal and electrostatic energy terms highly favored total free energy binding. CONCLUSION: The compounds Eriodictin, Vitexin, Cycloart-3, 24, 27-triol, Agigenin, Mangiferin, Mangiferolic acid, Schaftoside, 27-Hydroxymangiferonic acid, Quercetin, Azadirachtol, Cubebin, Isomangiferin, Isoquercitrin, Malicarpin, Orientin and procyanidin dimer exhibited satisfactory binding energy values when compared with standard molecules. The further iterative optimization of high-ranked compounds following validation by in vitro and in vivo techniques assists in discovering therapeutic anti-SARS-CoV-2 molecules.

GlmU Inhibitors as Promising Antibacterial Agents: A Review.

Bacterial infections are a major cause of mortality and morbidity in humans throughout the world. Infections due to resistant bacterial strains such as methicillin-resistant Staphyloccocusaureus vancomycin, resistant Enterococci, Klebsiella pneumoniae, Staphylococcus aureus, and Mycobacterium are alarming. Hence the development of new antibacterial agents, which act via a novel mechanism of action, became a priority in antibacterial research. One such approach to overcome bacterial resistance is to target novel protein and develop antibacterial agents that act via different mechanisms of action. Bacterial GlmU is one such bifunctional enzyme that catalyzes the two consecutive reactions during the biosynthesis of uridine 5'-diphospho-Nacetylglucosamine, an essential precursor for the biosynthesis of bacterial cell wall peptidoglycan. This enzyme comprises two distinct active sites; acetyltransferase and uridyltransferase and both these active sites act independently during catalytic reactions. GlmU is considered an attractive target for the design and development of newer antibacterial agents due to its important role in bacterial cell wall synthesis and the absence of comparable enzymes in humans. Availability of three dimensions X-crystallographic structures of GlmU and their known catalytic mechanism from different bacterial strains have instigated research efforts for the development of novel antibacterial agents. Several GlmU inhibitors belonging to different chemical classes like 2- phenylbenzofuran derivative, quinazolines, aminoquinazolines, sulfonamides, arylsulfonamide, D-glucopyranoside 6-phosphates, terreic acid, iodoacetamide, N-ethyl maleimide, and Nethylmaleimide etc., have been reported in the literature. In the present review, we present an update on GlmU inhibitors and their associated antibacterial activities. This review may be useful for the design and development of novel GlmU inhibitors with potent antibacterial activity.

The Optimisation of Carrier Selection in Dry Powder Inhaler Formulation and the Role of Surface Energetics.

This review examines the effects of particle properties on drug-carrier interactions in the preparation of a dry powder inhaler (DPI) formulation, including appropriate mixing technology. The interactive effects of carrier properties on DPI formulation performance make it difficult to establish a direct cause-and-effect relationship between any one carrier property and its effect on the performance of a DPI formulation. Alpha lactose monohydrate remains the most widely used carrier for DPI formulations. The physicochemical properties of α-lactose monohydrate particles, such as particle size, shape and solid form, are profoundly influenced by the method of production. Therefore, wide variations in these properties are inevitable. In this review, the role of surface energetics in the optimisation of dry powder inhaler formulations is considered in lactose carrier selection. Several useful lactose particle modification methods are discussed as well as the use of fine lactose and force control agents in formulation development. It is concluded that where these have been investigated, the empirical nature of the studies does not permit early formulation prediction of product performance, rather they only allow the evaluation of final formulation quality. The potential to leverage particle interaction dynamics through the use of an experimental design utilising quantifiable lactose particle properties and critical quality attributes, e.g., surface energetics, is explored, particularly with respect to when a Quality-by-Design approach has been used in optimisation.

Computational Molecular Modeling Studies of Some Mycobacterium Tuberculosis Alanine Racemase Inhibitors.

Alanine racemase is a pyridoxal-5'-phosphate dependent bacterial enzyme that provides the essential peptidoglycan precursor D-alanine, utilized for cell wall synthesis. This enzyme is ubiquitous throughout bacteria, including Mycobacterium tuberculosis, making it an attractive target for antibacterial drug discovery. We investigated the binding mode of twenty five reported Mycobacterium tuberculosis alanine racemase inhibitors. The results obtained from molecular docking studies emphasized the importance of inhibitor interaction with Lys42, Tyr46, Arg140, His172 and Tyr175 residues at the catalytic binding pocket of alanine racemase enzyme. The predicted binding free energies showed that van der Waals and nonpolar solvation interactions are the driving force for binding of inhibitors. Molecular dynamics simulation studies of four such inhibitor-alanine racemase systems were further explored to study the inhibition mechanism. The quantum chemical parameters calculated at the B3LYP/6-31G**++ level of theory indicated that the inhibitors must have low values of the lowest unoccupied molecular orbital energy and high values of electrostatic potential for stronger interactions. We expect that this study can provide significant theoretical guidance for design of potent Mycobacterium tuberculosis alanine racemase inhibitors in future.

Paediatric specific dosage forms: Patient and formulation considerations.

The total number of paediatric formulations available only account for a small proportion of the full therapeutic plethora required to effectively treat paediatrics and, therefore, the availability of high quality medicines designed specifically for children remains an ongoing challenge. Currently, the World Health Organisation (WHO) report that around 50% of medication issued for long-term conditions are not taken as advised, whilst it has also been established that, in general practice, around one tenth of medicines prescribed for children are either off-label or unlicensed. Such off-label and unlicensed use is owing to the considerable anatomical and physiological differences observed between paediatric subsets. Identifying such differences, is essential for better informing paediatric drug development and assisting regulatory reviews, whilst ensuring safe and effective therapeutic concentrations of pharmacological substances. Points covered: The review discusses factors affecting the safety, toxicity and efficacy of paediatric drug delivery systems. The research highlights features of the gastrointestinal tract and reports anatomical and physiological differences between paediatrics and adults. Additionally, differences observed in paediatric pharmacokinetic profiles (absorption, distribution, metabolism and elimination) due to physiological differences are also discussed. Furthermore, this review considers the advantages and limitations of current paediatric specific dosage forms available and assesses the acceptability of innovative small flexible solid oral dosage forms. Lastly, this review highlights factors affecting paediatric medicine adherence and acceptability and discusses the techniques available to overcome barriers associated with non-adherence.

Imidazoles and benzimidazoles as putative inhibitors of SARS-CoV-2 B.1.1.7 (Alpha) and P.1 (Gamma) variant spike glycoproteins: A computational approach.

COVID-19 is an unprecedented pandemic threatening global health, and variants were discovered rapidly after the pandemic. The two variants, namely the SARS-CoV-2 B.1.1.7 (Alpha) and P.1 (Gamma), were formed by the mutations in the receptor binding domain of spike glycoprotein (SGP). These two variants are known to possess a high binding affinity with the angiotensin-converting enzyme 2. Amidst the rapid spread of these mutant strains, research and development of novel molecules become tedious and labour-intensive. Imidazole and benzimidazole scaffolds were selected in this study based on their unique structural features and electron-rich environment, resulting in increased affinity against a variety of therapeutic targets. In the current study, imidazole- and benzimidazole-based anti-parasitic drugs are repurposed against SARS-CoV-2 Alpha and Gamma variant spike glycoproteins using computational strategies. Out of the screened 15 molecules, flubendazole and mebendazole have exhibited promising binding features to the two receptors (PDB ID: 7NEH and 7NXC), as evidenced by their glide score and binding free energy. The results are compared with that of the two standard drugs, remdesivir and hydroxychloroquine. Flubendazole and mebendazole have become convenient treatment options against mutant lineages of SARS-CoV-2. The edge of the flubendazole was further established by its stability in MD simulation conducted for 100 ns employing GROMACS software. Further, in vitro and in vivo studies are essential to understand, if flubendazole and mebendazole indeed hold the promise to manage SARS-CoV-2 mutant stains. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11696-021-01900-8.

DFT calculation, molecular docking, and molecular dynamics simulation study on substituted phenylacetamide and benzohydrazide derivatives.

The atomic and molecular properties of the title compounds were calculated by Jaguar using a basis set B3LYP/6-31G**++ with hybrid DFT in the gas phase, to determine the chemical reactivity. Analysis of quantum chemical features such as HOMO and LUMO explained that the electronic charge transfer occurred within the system through conjugated paths of the selected compounds. The nucleophilic and electrophilic reactive sites are recognized from the molecular electrostatic potential plot. Electrophilic and nucleophilic attack-prone molecular sites were predicted by mapping ALIE value to the molecular surface. The bond dissociation energy of the high active compound 15 (2-chloro-N-(2-(2-(2-(2-chlorobenzoyl)hydrazineyl)-2-oxoethoxy)phenyl)acetamide) was calculated to assess the probability of compound autoxidation or degradation. Further, molecular docking, binding free energy calculations, and ADMET profile of the degradation products (DPs) of compound 15 was carried out to determine the binding affinity and toxicity profile of the formed DPs compared with the parent compound. A 150-ns molecular dynamics (MD) simulation was performed to evaluate the binding stability of the compound 15/4URL complex using Desmond. Binding free energy and binding affinity of the complex were computed for 100 trajectory frames using the MM-GBSA approach.

Novel, Fully Characterised Bovine Taste Bud Cells of Fungiform Papillae.

Current understanding of functional characteristics and biochemical pathways in taste bud cells have been hindered due the lack of long-term cultured cells. To address this, we developed a holistic approach to fully characterise long term cultured bovine taste bud cells (BTBCs). Initially, cultured BTBCs were characterised using RT-PCR gene expression profiling, immunocytochemistry, flowcytometry and calcium imaging, that confirmed the cells were mature TBCs that express taste receptor genes, taste specific protein markers and capable of responding to taste stimuli, i.e., denatonium (2 mM) and quinine (462.30 µM). Gene expression analysis of forty-two genes implicated in taste transduction pathway (map04742) using custom-made RT-qPCR array revealed high and low expressed genes in BTBCs. Preliminary datamining and bioinformatics demonstrated that the bovine α-gustducin, gustatory G-protein, have higher sequence similarity to the human orthologue compared to rodents. Therefore, results from this work will replace animal experimentation and provide surrogate cell-based throughput system to study human taste transduction.

Benzohydrazide and Phenylacetamide Scaffolds: New Putative ParE Inhibitors.

Antibacterial resistance (ABR) is a major life-threatening problem worldwide. Rampant dissemination of ABR always exemplified the need for the discovery of novel compounds. However, to circumvent the disease, a molecular target is required, which will lead to the death of the bacteria when acted upon by a compound. One group of enzymes that have proved to be an effective target for druggable candidates is bacterial DNA topoisomerases (DNA gyrase and ParE). In our present work, phenylacetamide and benzohydrazides derivatives were screened for their antibacterial activity against a selected panel of pathogens. The tested compounds displayed significant antibacterial activity with MIC values ranging from 0.64 to 5.65 µg/mL. Amongst 29 title compounds, compounds 5 and 21 exhibited more potent and selective inhibitory activity against Escherichia coli with MIC values at 0.64 and 0.67 µg/mL, respectively, and MBC at onefold MIC. Furthermore, compounds exhibited a post-antibiotic effect of 2 h at 1× MIC in comparison to ciprofloxacin and gentamicin. These compounds also demonstrated the concentration-dependent bactericidal activity against E. coli and synergized with FDA-approved drugs. The compounds are screened for their enzyme inhibitory activity against E. coli ParE, whose IC50 values range from 0.27 to 2.80 µg/mL. Gratifyingly, compounds, namely 8 and 25 belonging to the phenylacetamide series, were found to inhibit ParE enzyme with IC50 values of 0.27 and 0.28 µg/mL, respectively. In addition, compounds were benign to Vero cells and displayed a promising selectivity index (169.0629-951.7240). Moreover, compounds 1, 7, 8, 21, 24, and 25 (IC50: <1 and Selectivity index: >200) exhibited potent activity in reducing the E. coli biofilm in comparison with ciprofloxacin, erythromycin, and ampicillin. These astonishing results suggest the potential utilization of phenylacetamide and benzohydrazides derivatives as promising ParE inhibitors for treating bacterial infections.

Development of an Age-Appropriate Mini Orally Disintegrating Carvedilol Tablet with Paediatric Biopharmaceutical Considerations.

Owing to considerable differences observed in anatomy and physiology between paediatric subsets, it has been well established that children respond to drugs differently compared to adults. Furthermore, from a formulation perspective, there is a distinct challenge to develop a dosage form that is capable of safely, accurately, and reliably delivering the dose across the whole paediatric population. Orally disintegrating mini-tablets (ODMT) have widely been considered as an age-appropriate formulation option that possess the ability for adequate dose flexibility, avoids swallowing difficulties, and exhibits superior stability due to its solid state. Within this study, two strengths (0.5 mg and 2 mg) of carvedilol ODMT formulations were developed using an excipient composition and load that is appropriate for paediatric use. The formulations demonstrated adequate mechanical strength (>20 N) and fast disintegration times (<30 s). Dissolution profiles observed were robust and comparable to the marketed conventional tablet formulation across various parts of the gastrointestinal (GI) tract in both the fed and fasted state, signifying appropriate efficacy, quality, and performance. As such, the formulations developed in this study show potential to address the need of an 'age-appropriate' formulation of carvedilol, as highlighted by the European Medicines Agency (EMA) Inventory of the Needs for Paediatric Medicine.

Multi-Analytical Framework to Assess the In Vitro Swallowability of Solid Oral Dosage Forms Targeting Patient Acceptability and Adherence.

A lack of effective intervention in addressing patient non-adherence and the acceptability of solid oral dosage forms combined with the clinical consequences of swallowing problems in an ageing world population highlight the need for developing methods to study the swallowability of tablets. Due to the absence of suitable techniques, this study developed various in vitro analytical tools to assess physical properties governing the swallowing process of tablets by mimicking static and dynamic stages of time-independent oral transitioning events. Non-anatomical models with oral mucosa-mimicking surfaces were developed to assess the swallowability of tablets; an SLA 3D printed in vitro oral apparatus derived the coefficient of sliding friction and a friction sledge for a modified tensometer measured the shear adhesion profile. Film coat hydration and in vitro wettability was evaluated using a high-speed recording camera that provided quantitative measurements of micro-thickness changes, simulating static in vivo tablet-mucosa oral processing stages with artificial saliva. In order to ascertain the discriminatory power and validate the multianalytical framework, a range of commonly available tablet coating solutions and new compositions developed in our lab were comparatively evaluated according to a quantitative swallowability index that describes the mathematical relationship between the critical physical forces governing swallowability. This study showed that the absence of a film coat significantly impeded the ease of tablet gliding properties and formed chalky residues caused by immediate tablet surface erosion. Novel gelatin- and λ-carrageenan-based film coats exhibited an enhanced lubricity, lesser resistance to tangential motion, and reduced stickiness than polyvinyl alcohol (PVA)-PEG graft copolymer, hydroxypropyl methylcellulose (HPMC), and PVA-coated tablets; however, Opadry® EZ possessed the lowest friction-adhesion profile at 1.53 a.u., with the lowest work of adhesion profile at 1.28 J/mm2. For the first time, the in vitro analytical framework in this study provides a fast, cost-effective, and repeatable swallowability ranking method to screen the in vitro swallowability of solid oral medicines in an effort to aid formulators and the pharmaceutical industry to develop easy-to-swallow formulations.

Acidic amino acids as counterions of ciprofloxacin: Effect on growth and pigment production in Staphylococcus aureus NCTC 8325 and Pseudomonas aeruginosa PAO1.

Antimicrobial resistance (AMR) is emerging as a global threat to public health. One of the strategies employed to combat AMR is the use of adjuvants which act to enhance or reinstate antimicrobial activity by inhibiting resistance mechanisms. However, these adjuvants are themselves not immune to selecting resistant phenotypes. Thus, there is a need to utilise mechanisms which are either less likely to or unable to trigger resistance. One commonly employed mechanism of resistance by microorganisms is to prevent antimicrobial uptake or efflux the antibiotic which manages to permeate its membrane. Here we propose amino acids as antimicrobial adjuvants that may be utilizing alternate mechanisms to fight AMR. We used a modified ethidium bromide (EtBr) efflux assay to determine its efflux in the presence of ciprofloxacin within Staphylococcus aureus (NCTC 8325) and Pseudomonas aeruginosa (PAO1). In this study, aspartic acid and glutamic acid were found to inhibit growth of both bacterial species. Moreover, a reduced production of toxic pigments, pyocyanin and pyoverdine by P. aeruginosa was also observed. As evident from similar findings with tetracycline, these adjuvants, may be a way forward towards tackling antimicrobial resistance.

Profiling gene expression dynamics underpinning conventional testing approaches to better inform pre-clinical evaluation of an age appropriate spironolactone formulation.

There is a need to accelerate paediatric formulation evaluation and enhance quality of early stage data in drug development to alleviate the information pinch point present between formulation development and clinical evaluation. This present work reports application of DNA microarrays as a high throughput screening tool identifying markers for prediction of bioavailability and formulation driven physiological responses. With a focus on enhancing paediatric medicine provision, an oral liquid spironolactone suspension was formulated addressing a paediatric target product profile. Caco-2 cells cultured on transwell inserts were implemented in transport assays in vitro and DNA microarrays were used to examine gene expression modulation. Wistar rats were used to derive in vivo bioavailability data. In vitro, genomic, and in vivo data sets were concurrently evaluated linking drug transport and the genomic fingerprint generated by spironolactone formulation exposure. Significant changes in gene expression are reported as a result of formulation exposure. These include genes coding for ATP-binding cassette (ABC) transporters, solute carrier (SLC) transporters, cytochrome P450 (CYP) enzymes, and carboxylesterase enzymes. Genomic findings better inform pre-clinical understanding of pharmacokinetic and pharmacodynamic responses to spironolactone and its active metabolites than current in vitro drug transport assays alone.

Identification of Antimycobacterial Agent Using In Silico Virtual Screening, ADME Prediction, Docking, and Molecular Dynamics Simulations Approach.

BACKGROUND: The widespread hazardous issue of antibiotics resistance can be overcome by the development of target based potent antibacterial agents. Filamentous temperature-sensitive mutant Z (FtsZ), a simpler structural prokaryotic homolog of eukaryotic cytoskeletal tubulin, was considered as a competent target in antibacterial drug discovery. OBJECTIVE: The purpose of the present work is to evaluate the antitubercular activity of virtual hits by funnel-shaped filtering with glide docking, followed by MM-GBSA binding energy and molecular dynamics simulation. Pharmacokinetics and biochemical activity of the computationally screened virtual hits have been studied to focus their potential to inhibit the bacterial cell division. METHODS: The docking study was performed against the crystal structure of Staphylococcus aureus and Mycobacterium tuberculosis FtsZ protein with the hits obtained from High Throughput Virtual Screening using the Glide module in Schrodinger. ADME profile and 50 ns molecular dynamics simulation studies were performed using the Schrödinger suite. The minimal inhibitory concentration of the test compounds was determined by the colorimetric method by the Resazurin Microtiter plate Assay. RESULTS: The binding of hit molecules T5427054 and 6M356S was mainly supported by van der Waals interaction and an electrostatic component of solvation energy computed by the MM-GBSA method. 50 ns MD simulation built stability and dynamic property of the best-docked complex T5427054/2Q1Y. Both the hit molecules displayed antimycobacterial activity with minimal inhibitory concentration 500 µg/mL. CONCLUSION: In this study, it is found that new screened hit molecules with better theoretical results could be preferred to use as antimycobacterial agents, and further their structural modification might be improved antimycobacterial properties of hit molecules.

Formulation and Bioequivalence Testing of Fixed-Dose Combination Orally Disintegrating Tablets for the Treatment of Tuberculosis in the Paediatric Population.

Tuberculosis (TB) is believed to affect around 10 million people worldwide. Treatment for TB includes isoniazid and rifampicin, with fixed-dose combination (FDC) recommended for improved patient compliance. Similarly, orally disintegrating tablets (ODTs) are an increasingly popular dosage form that aid compliance since they do not require swallowing. In this study ODTs of isoniazid and rifampicin, either as discrete or FDC doses, were formulated and bioequivalence between single and combination doses compared using in vitro and in silico approaches. Dissolution profiles were compared using FDA advised difference (f1) and similarity (f2) testing in biorelevant media. Rifampicin release from FDCs decreased by approximately 15% in fed-state media (failed f1 and f2), which was attributed to enhanced rifampicin degradation in the presence of isoniazid at lower pH. Apparent permeability (Papp) values derived from Caco-2 transport studies were included alongside dissolution results into a physiologically based pharmacokinetic (PBPK) model, to simulate in vivo bioavailability in healthy subjects. Models showed no difference in bioavailability between formulations or dosing (fasted or fed) state, despite the failures in dissolution-based bioequivalence testing, highlighting shortcomings in f1 and f2 assessment and the strength of PBPK models.

Evaluation of anti-biofilm activity of acidic amino acids and synergy with ciprofloxacin on Staphylococcus aureus biofilms.

Acidic amino acids, aspartic acid (Asp) and glutamic acid (Glu) can enhance the solubility of many poorly soluble drugs including ciprofloxacin (Cip). One of the mechanisms of resistance within a biofilm is retardation of drug diffusion due to poor penetration across the matrix. To overcome this challenge, this work set to investigate novel counter ion approach with acidic amino acids, which we hypothesised will disrupt the biofilm matrix as well as simultaneously improve drug effectiveness. The anti-biofilm activity of D-Asp and D-Glu was studied on Staphylococcus aureus biofilms. Synergistic effect of combining D-amino acids with Cip was also investigated as a strategy to overcome anti-microbial resistance in these biofilms. Interestingly at equimolar combinations, D-Asp and D-Glu were able to significantly disperse (at 20 mM and 40 mM) established biofilms and inhibit (at 10 mM, 20 mM and 40 mM) new biofilm formation in the absence of an antibiotic. Moreover, our study confirmed L-amino acids also exhibit anti-biofilm activity. The synergistic effect of acidic amino acids with Cip was observed at lower concentration ranges (<40 mM amino acids and <90.54 µM, respectively), which resulted in 96.89% (inhibition) and 97.60% (dispersal) reduction in CFU with exposure to 40 mM amino acids. Confocal imaging indicated that the amino acids disrupt the honeycomb-like extracellular DNA (eDNA) meshwork whilst also preventing its formation.