Quantification of rifampicin loaded into inhaled polymeric nanoparticles by reversed phase high-performance liquid chromatography in pulmonary nonphagocytic cellular uptake.

Rifampicin is an antibiotic effective against both Gram-negative and Gram-positive bacteria and is commonly used as a first-line treatment for tuberculosis caused by Mycobacterium tuberculosis. In this study, a reversed-phase high-performance liquid chromatography method was developed and validated to assess rifampicin, either free or combined with ascorbic acid, loaded into chitosan/Tween 80-coated alginate nanoparticles. The method utilized a reversed-phase C18 Restek column with specific chromatographic conditions: a mobile phase of 60 : 40 ratios of methanol/buffer phosphate (pH 7.0), at a flow rate of 0.8 mL min-1, and an injection volume of 15 µL. rifampicin and the internal standard (rifamycin) had retention times of 4.0 and 2.5 min, respectively, and were detected at 334 nm. The method demonstrated the stability of stored samples after freezing-thawing cycles and specificity for rifampicin, even in the presence of degradation products from stress conditions. The high-performance liquid chromatography method was found to be specific, precise, robust, and sensitive. Results indicated that rifampicin accumulation and uptake kinetics varied based on cell type, formulation (free or loaded in nanoparticles), rifampicin concentration, and incubation time. Confocal fluorescence microscopy images supported these findings, showing isothiocyanate fluorescein nanoparticles distribution in different intracellular regions depending on the cell type used. The societal impact of this research lies in its potential to advance the treatment of respiratory infectious diseases, such as tuberculosis, through the development of more effective and specific drug delivery methods. By optimizing the way drugs, particularly rifampicin in this case, interact with lung cells, we aim to achieve greater treatment efficacy and alleviate the overall burden of disease. Furthermore, our study offers novel insights into the intracellular behavior of rifampin from polymeric nanoparticles, paving the way for personalized medicine approaches in the treatment of respiratory infections. This dual focus on social impact and innovation underscores our commitment to improving global health outcomes and addressing pressing public health challenges.

A novel fluorescent sensor for selective rifampicin detection based on the bio-inspired molecularly imprinted polymer-AgInS2/ZnS quantum dots.

A fluorescent sensing material based on the ternary core-shell quantum dots with outstanding optical properties and a bio-inspired molecularly imprinted polymer (MIP) as a recognition element has been prepared for selective detection of rifampicin (RFP). Firstly, AgInS2/ZnS core/shell quantum dots (ZAIS QDs) were prepared by a hydrothermal process. Then, the fluorescent sensor was prepared by coating these QDs by a dopamine-based MIP layer. The fluorescence of MIP@ZAIS QDs was quenched by RFP probably due to the photoinduced electron transfer process. The quenching constant was much higher for MIP@ZAIS QDs than the non-imprinted polymer@QDs, indicating that MIP@ZAIS QDs could selectively recognize RFP. Under the optimized conditions, the sensor had a good linear relationship at the RFP concentration range of 5.0 to 300 nM and the limit of detection was 1.25 nM. The respond time of the MIP@ZAIS QDs was 5 min, and the imprinting factor was 6.3. It also showed good recoveries ranging from 98 to 101%, for analysis of human plasma samples. The method is simple and effective for the detection of RFP and offers a practical application for the rapid analysis of human plasma samples.

Novel SmartReservoirs for hydrogel-forming microneedles to improve the transdermal delivery of rifampicin.

Hydrogel-forming microneedles (HF-MNs) are composed of unique cross-linked polymers that are devoid of the active pharmaceutical ingredient (API) within the microneedle array. Instead, the API is housed in a reservoir affixed on the top of the baseplate of the HF-MNs. To date, various types of drug-reservoirs and multiple solubility-enhancing approaches have been employed to deliver hydrophobic molecules combined with HF-MNs. These strategies are not without drawbacks, as they require multiple manufacturing steps, from solubility enhancement to reservoir production. However, this current study challenges this trend and focuses on the delivery of the hydrophobic antibiotic rifampicin using SmartFilm-technology as a solubility-enhancing strategy. In contrast to previous techniques, smart drug-reservoirs (SmartReservoirs) for hydrophobic compounds can be manufactured using a one step process. In this study, HF-MNs and three different concentrations of rifampicin SmartFilms (SFs) were produced. Following this, both HF-MNs and SFs were fully characterised regarding their physicochemical and mechanical properties, morphology, Raman surface mapping, the interaction with the cellulose matrix and maintenance of the loaded drug in the amorphous form. In addition, their drug loading and transdermal permeation efficacy were studied. The resulting SFs showed that the API was intact inside the cellulose matrix within the SFs, with the majority of the drug in the amorphous state. SFs alone demonstrated no transdermal penetration and less than 20 ± 4 µg of rifampicin deposited in the skin layers. In contrast, the transdermal permeation profile using SFs combined with HF-MNs (i.e. SmartReservoirs) demonstrated a 4-fold increase in rifampicin deposition (80 ± 7 µg) in the skin layers and a permeation of approx. 500 ± 22 µg. Results therefore illustrate that SFs can be viewed as novel drug-reservoirs (i.e. SmartReservoirs) for HF-MNs, achieving highly efficient loading and diffusion properties through the hydrogel matrix.

Assessing Polymorphic Purity of Rifampicin in Double and Triple-Drug Fixed-Dose Combination Products.

First-line tuberculostatic agents, Rifampicin (RIF), Isoniazid (ISH), Ethambutol (ETB), and Pyrazinamide (PZA) are generally administered as a fixed-dose combination (FDC) for improving patient adherence. The major quality challenge of these FDC products is their variable bioavailability, where RIF and its solid state are key factors. In this work, the analysis of the impact of the polymorphism in the performance of RIF in RIF-ISH and PZA-RIF-ISH combined products was carried out by an overall approach that included the development and validation of two methodologies combining near-infrared (NIR) spectroscopy and partial least squares (PLS) to the further evaluation of commercial products. For NIR-PLS methods, training and validation sets were prepared with mixtures of Form I/Form II of RIF, and the appropriate amount of ISH (for double associations) or ISH-PZA (for triple associations). The corresponding matrix of the excipients was added to the mixture of APIs to simulate the environment of each FDC product. Four PLS factors, reduced spectral range, and the combination of standard normal variate and Savitzky-Golay 1st derivative (SNV-D') were selected as optimum data pre-treatment for both methods, yielding satisfactory recoveries during the analysis of validation sets (98.5±2.0%, and 98.7±1.8% for double- and triple-FDC products, respectively). The NIR-PLS model for RIF-ISH successfully estimated the polymorphic purity of Form II in double-FDC capsules (1.02 ± 0.02w/w). On the other hand, the NIR-PLS model for RIF-ISH-PZA detected a low purity of Form II in triple FDC tablets (0.800 ± 0.021w/w), these results were confirmed by X-ray powder diffraction. Nevertheless, the triple-FDC tablets showed good performance in the dissolution test (Q=99-102%), implying a Form II purity about of 80% is not low enough to affect the safety and efficacy of the product.

Mechanically stable rifampin antibiotic cement inhibits Pseudomonas aeruginosa biofilm surface growth.

Rifampin has been proven to be effective in the treatment of prosthetic infections due to its ability to intercalate into biofilms. The use of rifampin in antibiotic spacers is not well described, which would be especially important in the local periprosthetic environment where parenteral doses have poor penetration. The null hypothesis tests if rifampin use in polymethyl methacrylate (PMMA) cement will show no clinically significant impact on mechanical strength at antibiotic concentrations that remain bactericidal. Test antibiotic cement samples supplemented with 0, 30, 50, 100, 150, or 200 mg of rifampin into a standard 40 g bag were tested for compression to failure using published ASTM standards. The samples were then inoculated with Pseudomonas aeruginosa and either evaluated for lipopolysaccharide (LPS) presence as a marker of biofilm or tested by elution as the Kirby Bauer assay. Rifampin concentrations of 30 and 50 mg, showed no statistically different mechanical characteristics from control PMMA (p > 0.05). The 100-mg sample fell within the acceptable range of compressive strength and had significantly less LPS and bacterial presence compared to the control at 12 and 24 h. The ability of PMMA with 100 mg of rifampin to maintain its structural integrity and have significant bacterial inhibition at 12 and 24 h makes it a great candidate as an antibiotic bone cement additive. PMMA loaded with up to 100 mg of rifampin shows promise in the treatment and prevention of periprosthetic joint infection for total knee and total hip arthroplasty.

High-resolution landscape of an antibiotic binding site.

Antibiotic binding sites are located in important domains of essential enzymes and have been extensively studied in the context of resistance mutations; however, their study is limited by positive selection. Using multiplex genome engineering1 to overcome this constraint, we generate and characterize a collection of 760 single-residue mutants encompassing the entire rifampicin binding site of Escherichia coli RNA polymerase (RNAP). By genetically mapping drug-enzyme interactions, we identify an alpha helix where mutations considerably enhance or disrupt rifampicin binding. We find mutations in this region that prolong antibiotic binding, converting rifampicin from a bacteriostatic to bactericidal drug by inducing lethal DNA breaks. The latter are replication dependent, indicating that rifampicin kills by causing detrimental transcription-replication conflicts at promoters. We also identify additional binding site mutations that greatly increase the speed of RNAP.Fast RNAP depletes the cell of nucleotides, alters cell sensitivity to different antibiotics and provides a cold growth advantage. Finally, by mapping natural rpoB sequence diversity, we discover that functional rifampicin binding site mutations that alter RNAP properties or confer drug resistance occur frequently in nature.

In vitro, in-vivo, and in-silico investigation of physicochemical interactions between pioglitazone and rifampicin.

There is a possibility of in-situ physicochemical interactions between concomitantly administered drugs. This study aimed to investigate such physicochemical interactions between pioglitazone and rifampicin. Pioglitazone exhibited significantly higher dissolution in the presence of rifampicin, while the dissolution of rifampicin remained unaffected. The solid-state characterization of precipitates recovered after pH-shift dissolution experiments revealed the conversion of pioglitazone into an amorphous form in the presence of rifampicin. The Density Function Theory (DFT) calculations showed the intermolecular hydrogen bonding between rifampicin and pioglitazone. In-situ conversion of pioglitazone in amorphous form and subsequent supersaturation of GIT milieu translated into significantly higher in-vivo exposure of pioglitazone and its metabolites (M-III and M-IV) in Wistar rats. Therefore, it is advisable to consider the possibility of physicochemical interactions between concomitantly administered drugs. Our findings may be beneficial in tailoring the dose of concomitantly administered drugs, particularly for chronic conditions that entail polypharmacy.

pH-responsive microparticles of rifampicin for augmented intramacrophage uptake and enhanced antitubercular efficacy.

In this study we present pH-responsive rifampicin (RIF) microparticles comprising lecithin and a biodegradable hydrophobic polymer, polyethylene sebacate (PES), to achieve high intramacrophage delivery and enhanced antitubercular efficacy. PES and PES-lecithin combination microparticles (PL MPs) prepared by single step precipitation revealed average size of 1.5 to 2.7 µm, entrapment efficiency âˆ¼ 60 %, drug loading 12-15 % and negative zeta potential. Increase in lecithin concentration enhanced hydrophilicity. PES MPs demonstrated faster release in simulated lung fluid pH 7.4, while lecithin MPs facilitated faster and concentration dependent release in acidic artificial lysosomal fluid (ALF) pH 4.5 due to swelling and destabilization confirmed by TEM. PES and PL (1:2) MPs exhibited comparable macrophage uptake which was âˆ¼ 5-fold superior than free RIF, in the RAW 264.7 macrophage cells. Confocal microscopy depicted intensified accumulation of the MPs in the lysosomal compartment, with augmented release of coumarin dye from the PL MPs, confirming pH-triggered increased intracellular release. Although, PES MPs and PL (1:2) MPs displayed comparable and high macrophage uptake, antitubercular efficacy against macrophage internalised M. tuberculosis was significantly higher with PL (1:2) MPs. This suggested great promise of the pH-sensitive PL (1:2) MPs for enhanced antitubercular efficacy.

In vitro Dissolution Testing of Rifampicin Powder Formulations For Prediction of Plasma Concentration-Time Profiles After Inhaled Delivery.

PURPOSE: The purpose of this study was to evaluate the in vitro lung dissolution of amorphous and crystalline powder formulations of rifampicin in polyethylene oxide (PEO) and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), and to predict the in vivo plasma concentration-time profiles using the in vitro data. METHODS: The in vitro dissolution and permeation profiles of respirable rifampicin particles were studied using a custom-made dissolution apparatus. Data from the in vitro dissolution test were used to estimate the parameters to be used as the input for the simulation of in vivo plasma concentration-time profiles using STELLA® software. For prediction of in vivo profiles, a one-compartment model either with a first order elimination or with a Michaelis-Menten kinetics-based elimination was used. RESULTS: Compared to the crystalline formulation, the amorphous formulation showed rapid in vitro dissolution suggesting their possible faster in vivo absorption and higher plasma concentrations of rifampicin following lung delivery. However, the simulations suggested that both powder formulations would result in similar plasma-concentration time profiles of rifampicin. CONCLUSIONS: Use of an in vitro dissolution test coupled with a simulation model for prediction of plasma-concentration time profiles of an inhaled drug was demonstrated in this work. These models can also be used in the design of inhaled formulations by controlling their release and dissolution properties to achieve desired lung retention or systemic absorption following delivery to the lungs.

Development and Optimization of a New UPLC-UV/MS Method through DoE and MLR for Detecting Substandard Drug Products to Treat Tuberculosis.

Drug products used for treating tuberculosis are one of the most widely reported medicines to be classified as falsified or substandard in low- and middle-income countries, representing a major hazard to health. The aim of this study was, firstly, to develop an ultra-performance liquid chromatography (UPLC) method which is able to analyze fixed combination tablets with up to four active pharmaceutical ingredients, including isoniazid, pyrazinamide, rifampicin, and ethambutol. Secondly, we aimed to optimize it through the design of experiments and multi-linear regression based on a central composite design and to validate it according to the guidelines of the International Conference on Harmonization. The application of this tools enabled the identification of the influential factors (flow rate, formic acid, and temperature) and their effects on the studied responses (retention factor and percentage for each drug) as part of the quality by design approach. The method proved to be to be linear in the range from 5.0 to 15 µg/mL for isoniazid, pyrazinamide, and rifampicin, being precise (<1%) and accurate (97−101%). In addition, the method validated for ethambutol proved to be linear from 1.4 to 4.2 µg/mL, as well as precise (0.54%) and accurate (97.3%). The method was stability indicated for all the active pharmaceutical ingredients studied and was able to detect two substandard formulations sampled on the African market.

One-pot synthesis of α-Linolenic acid nanoemulsion-templated drug-loaded silica mesocomposites as efficient bactericide against drug-resistant Mycobacterium tuberculosis.

Nowadays, pathogenic infection has posed a severe threat to the public health and environmental sanitation, urging a continuous search of efficacious and safe bactericidal agents of various formulated forms. Here, a facile one-pot hydrothermal preparation of mesoporous silica nanoparticles using ultrasonication-assisted nanoemulsion of α-Linolenic acid (α-LA) as template was developed. The formed silica mesocomposite at water/fatty-acid surface provides an easy yet green synthesis route, which can be generalized for the further encapsulation of hydrophobic drugs such as antimycobacterial Rifampicin (RIF). The obtained α-LA nanoemulsion-templated silica nanoparticles (LNS NPs), with a weight content of ∼17% α-LA in the composite, showed apparent antibacterial effect against Staphylococcus aureus (S. aureus). By comparison, the removal of α-LA from the silica nanoparticles (LNS-1 NPs) resulted in the composite of enlarged pore size with negligible bactericidal activities. Notably, the Isoniazide (INH) and Rifampicin (RIF)-encapsulated LNS NPs exhibited outstanding antimycobacterial activity against both drug-sensitive and drug-resistant Mycobacterium tuberculosis (M. tuberculosis). The obtained highly biocompatible, biosafe and low-energy consumptive α-LA-contained mesostructured silica-based bactericide holds promising therapeutic potentials to tackle the emerging drug-resistant infectious microbes.

Tuberculosis drug discovery: Progression and future interventions in the wake of emerging resistance.

The emergence of drug resistance continues to afflict TB control where drug resistant strains have become a global health concern. Contrary to drug-sensitive TB, the treatment of MDR/XDR-TB is more complicated requiring the administration of second-line drugs that are inefficient than the first line drugs and are associated with greater side effects. The emergence of drug resistant Mtb strains had coincided with an innovation void in the field of drug discovery of anti-mycobacterials. However, the approval of bedaquiline and delamanid recently for use in MDR/XDR-TB has given an impetus to the TB drug discovery. The review discusses the drug discovery efforts in the field of tuberculosis with a focus on the strategies adopted and challenges confronted by TB research community. Here, we discuss the diverse clinical candidates in the current TB drug discovery pipeline. There is an urgent need to combat the current TB menace through multidisciplinary approaches and strategies making use of the recent advances in understanding the molecular biology and pathogenesis of Mtb. The review highlights the recent advances in drug discovery, with the host directed therapeutics and nanoparticles-drug delivery coming up as important tools to fight tuberculosis in the future.

Cascade-Targeting Poly(amino acid) Nanoparticles Eliminate Intracellular Bacteria via On-Site Antibiotic Delivery.

Intracellular bacteria in latent or dormant states tolerate high-dose antibiotics. Fighting against these opportunistic bacteria has been a long-standing challenge. Herein, the design of a cascade-targeting drug delivery system (DDS) that can sequentially target macrophages and intracellular bacteria, exhibiting on-site drug delivery, is reported. The DDS is fabricated by encapsulating rifampicin (Rif) into mannose-decorated poly(α-N-acryloyl-phenylalanine)-block-poly(ß-N-acryloyl-d-aminoalanine) nanoparticles, denoted as Rif@FAM NPs. The mannose units on Rif@FAM NPs guide the initial macrophage-specific uptake and intracellular accumulation. After the uptake, the detachment of mannose in acidic phagolysosome via Schiff base cleavage exposes the d-aminoalanine moieties, which subsequently steer the NPs to escape from lysosomes and target intracellular bacteria through peptidoglycan-specific binding, as evidenced by the in situ/ex situ co-localization using confocal, flow cytometry, and transmission electron microscopy. Through the on-site Rif delivery, Rif@FAM NPs show superior in vitro and in vivo elimination efficiency than the control groups of free Rif or the DDSs lacking the macrophages- or bacteria-targeting moieties. Furthermore, Rif@FAM NPs remodel the innate immune response of the infected macrophages by upregulating M1/M2 polarization, resulting in a reinforced antibacterial capacity. Therefore, this biocompatible DDS enabling macrophages and bacteria targeting in a cascade manner provides a new outlook for the therapy of intracellular pathogen infection.

Instant hydrogelation encapsulates drugs onto implants intraoperatively against osteoarticular tuberculosis.

Osteoarticular Tuberculosis (TB) is a challenging issue because of its chronicity and recurrence. Many drug delivery systems (DDSs) have been developed for general chemotherapy. Herein, we take advantage of instant hydrogelation to in situ encapsulate drugs onto implants intraoperatively, optimizing the drug release profile against osteoarticular TB. First-line chemodrugs, i.e. rifampicin (RFP) and isoniazid (INH) are firstly loaded on tricalcium phosphate (TCP). Then, the encapsulating hydrogel is fabricated by dipping in chitosan (CS) and ß-glycerophosphate (ß-GP) solution and heating at 80 °C for 40 min. The hydrogel encapsulation inhibits explosive drug release initially, but maintains long-term drug release (INH, 158 days; RFP, 53 days) in vitro. Therefore, this technique could inhibit bone destruction and inflammation from TB effectively in vivo, better than our previous ex situ prepared DDSs. The encapsulating technology, i.e. instant hydrogelation of drug-loaded implants, shows potential for regulating the type and ratio of drugs, elastic and viscous modulus of the hydrogel according to the state of illness intraoperatively for optimal drug release.

Intracellular Accumulation of Novel and Clinically Used TB Drugs Potentiates Intracellular Synergy.

The therapeutic repertoire for tuberculosis (TB) remains limited despite the existence of many TB drugs that are highly active in in vitro models and possess clinical utility. Underlying the lack of efficacy in vivo is the inability of TB drugs to penetrate microenvironments inhabited by the causative agent, Mycobacterium tuberculosis, including host alveolar macrophages. Here, we determined the ability of the phenoxazine PhX1 previously shown to be active against M. tuberculosis in vitro to differentially penetrate murine compartments, including plasma, epithelial lining fluid, and isolated epithelial lining fluid cells. We also investigated the extent of permeation into uninfected and M. tuberculosis-infected human macrophage-like Tamm-Horsfall protein 1 (THP-1) cells directly and by comparing to results obtained in vitro in synergy assays. Our data indicate that PhX1 (4,750 ± 127.2 ng/ml) penetrates more effectively into THP-1 cells than do the clinically used anti-TB agents, rifampin (3,050 ± 62.9 ng/ml), moxifloxacin (3,374 ± 48.7 ng/ml), bedaquiline (4,410 ± 190.9 ng/ml), and linezolid (770 ± 14.1 ng/ml). Compound efficacy in infected cells correlated with intracellular accumulation, reinforcing the perceived importance of intracellular penetration as a key drug property. Moreover, we detected synergies deriving from redox-stimulatory combinations of PhX1 or clofazimine with the novel prenylated amino-artemisinin WHN296. Finally, we used compound synergies to elucidate the relationship between compound intracellular accumulation and efficacy, with PhX1/WHN296 synergy levels shown to predict drug efficacy. Collectively, our data support the utility of the applied assays in identifying in vitro active compounds with the potential for clinical development. IMPORTANCE This study addresses the development of novel therapeutic compounds for the eventual treatment of drug-resistant tuberculosis. Tuberculosis continues to progress, with cases of Mycobacterium tuberculosis (M. tuberculosis) resistance to first-line medications increasing. We assess new combinations of drugs with both oxidant and redox properties coupled with a third partner drug, with the focus here being on the potentiation of M. tuberculosis-active combinations of compounds in the intracellular macrophage environment. Thus, we determined the ability of the phenoxazine PhX1, previously shown to be active against M. tuberculosis in vitro, to differentially penetrate murine compartments, including plasma, epithelial lining fluid, and isolated epithelial lining fluid cells. In addition, the extent of permeation into human macrophage-like THP-1 cells and H37Rv-infected THP-1 cells was measured via mass spectrometry and compared to in vitro two-dimensional synergy and subsequent intracellular efficacy. Collectively, our data indicate that development of new drugs will be facilitated using the methods described herein.

Porous particles and novel carrier particles with enhanced penetration for efficient pulmonary delivery of antitubercular drugs.

This study aimed to design dry powder inhaler formulations using a hydrophilic polymeric polysaccharide, phytoglycogen (PyG), as a multi-functional additive that increases the phagocytic activity of macrophage-like cells and enhances pulmonary delivery of drugs. The safety and usefulness of PyG were determined using in vitro cell-based studies. Dry powder inhaler formulations of an antitubercular drug, rifampicin, were fabricated by spray drying with PyG. The cytotoxicity, effects on phagocytosis, particle size, and morphology were evaluated. The aerosolization properties of the powder formulations were evaluated using an Andersen cascade impactor (ACI). Scanning electron microscope images of the particles on each ACI stage were captured to observe the deposition behavior. PyG showed no toxicity in A549, Calu-3, or RAW264.7 cell lines. At concentrations of 0.5 and 1 g/L, PyG facilitated the cellular uptake of latex beads and the expression of pro-inflammatory cytokine genes in RAW264.7 cells. Formulations with outstanding inhalation potential were produced. The fine particle fraction (aerodynamic size 2-7 µm) of the porous particle batch reached nearly 60%, whereas in the formulation containing wrinkled carrier particles, the extra-fine particle fraction (aerodynamic particle size < 2 µm) was 25.0% ± 1.7%. The deposition of porous and wrinkled particles on individual ACI stages was distinct. The inclusion of PyG dramatically improved the inhalation performance of porous and wrinkled powder formulations. These easily inhaled immunostimulatory carrier particles may advance the state of research by enhancing the therapeutic effect and alveolar delivery of antitubercular drugs.

In Situ Biosynthesis of a Metal Nanoparticle Encapsulated in Alginate Gel for Imageable Drug-Delivery System.

Development of drug-delivery systems that allow simultaneous in vivo imaging has gained much interest. We report a novel strategy to encapsulate metal nanoparticles (NPs) within alginate gel for in vivo imaging. The cell lysate of recombinant Escherichia coli strain, expressing Arabidopsis thaliana phytochelatin synthase and Pseudomonas putida metallothionein genes, was encapsulated within the alginate gel. Incubation of alginate gel with metal ion precursors followed by UV irradiation resulted in the synthesis of high concentrations of metal NPs, such as Au, Ag, CdSe, and EuSe NPs, within the gel. The alginate gel with metal NPs was used as a drug-delivery system by further co-encapsulating doxorubicin and rifampicin, the release of which was made to be pH-dependent. This system can be conveniently and safely used for in vitro and in vivo bioimaging, enabled by the metal NPs formed within the gel matrix without using toxic reducing reagents or surfactants.

Ultrasound Triggered Drug Release from Affinity-Based ß-Cyclodextrin Polymers for Infection Control.

This work demonstrates a slow, sustained drug delivery system that provides on-demand delivery bursts through the application of pulsed therapeutic ultrasound (TUS). Insoluble ß-cyclodextrin-polymer (pCD) disks were loaded with a saturated antibiotic solution of rifampicin (RIF) and used for drug delivery studies. To obtain on-demand release from the implants, TUS was applied at an intensity of 1.8 W/cm2. The therapeutic efficacy of the combination treatment was assessed in bacterial culture via an in vitro Staphylococcus aureus bioluminescence assay. The results demonstrated that the application of pulsed TUS at 3 MHz and 1.8 W/cm2 to pCD implants leads to a significantly higher short-term burst in the drug release rate compared to samples not treated with TUS. The addition of TUS increased the drug release by 100% within 4 days. The pCD disk + RIF stimulated with TUS showed a comparatively higher bacterial eradication with CFU/mL of 4.277E+09, and 8.00E+08 at 1 and 24 h compared with control treated bacteria at 1.48E+10. Overall, these results suggest that the addition of pulsed TUS could be an effective technology to noninvasively expedite antibiotic release on demand at desired intervals.

Mannose-conjugated chitosan nanoparticles for delivery of Rifampicin to Osteoarticular tuberculosis.

Tuberculosis (TB) is a potentially fatal contagious disease and is a second leading infectious cause of death in the world. Osteoarticular TB is treated using standard regimen of 1st and 2nd line anti-tubercular drugs (ATDs) for extensive period of 8-20 months. These drugs are commonly administered in high doses by oral route or by intravenous route, because of their compromised bioavailability. The common drawbacks associated with conventional therapy are poor patient compliance due to long treatment period, frequent and high dosing, and toxicity. This aspect marks for the need of formulations to eliminate these drawbacks. MTB is an intracellular pathogen of mononuclear phagocyte. This attribute makes nanotherapeutics an ideal approach for MTB treatment as macrophages capture nano forms. Polymeric nanoparticles are removed from the body by opsonization and phagocytosis, which forms an ideal strategy to target macrophage containing mycobacteria. To further improve targetability, the nanoparticles are conjugated with ligand, which serves as an easy substrate for the receptors present on the macrophage surface. The purpose of present work was to develop intra-articular injectable in situ gelling system containing polymeric nanoparticles, which would have promising advantages over conventional method of treatment. The rationale behind formulating nanoparticle incorporated in situ gel-based system was to ensure localization of the formulation in intra-articular cavity along with sustained release and conjugation of nanoparticles with mannose as ligand to improve uptake by macrophages. Rifampicin standard ATD was formulated into chitosan nanoparticles. Chitosan with 85% degree of deacetylation (DDA) and sodium tripolyphosphate (TPP) as the crosslinking agent was used for preparing nanoparticles. The percent entrapment was found to be about 71%. The prepared nanoparticles were conjugated with mannose. Conjugation of ligand was ascertained by performing Fourier transformed infrared spectroscopy. The particle size was found to be in the range of 130-140 nm and zeta potential of 38.5 mV. Additionally, we performed scanning electron microscopy to characterize the surface morphology of ligand-conjugated nanoparticles. The conjugated chitosan nanoparticles were incorporated into in situ gelling system comprising Poloxamer 407 and HPMC K4M. The gelling system was evaluated for viscosity, gelling characteristics, and syringeability. The drug release from conjugated nanoparticles incorporated in in situ gel was found to be about 70.3% at the end of 40 h in simulated synovial fluid following zero-order release kinetics. Based on the initial encouraging results obtained, the nanoparticles are being envisaged for ex vivo cellular uptake study using TB-infected macrophages.

Designing Out PXR Activity on Drug Discovery Projects: A Review of Structure-Based Methods, Empirical and Computational Approaches.

This perspective discusses the role of pregnane xenobiotic receptor (PXR) in drug discovery and the impact of its activation on CYP3A4 induction. The use of structural biology to reduce PXR activity on drug discovery projects has become more common in recent years. Analysis of this work highlights several important molecular interactions, and the resultant structural modifications to reduce PXR activity are summarized. The computational approaches undertaken to support the design of new drugs devoid of PXR activation potential are also discussed. Finally, the SAR of empirical design strategies to reduce PXR activity is reviewed, and the key SAR transformations are discussed and summarized. In conclusion, this perspective demonstrates that PXR activity can be greatly diminished or negated on active drug discovery projects with the knowledge now available. This perspective should be useful to anyone who seeks to reduce PXR activity on a drug discovery project.