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.

Synergistic bactericidal combinations between gentamicin and chitosan capped ZnO nanoparticles: A promising strategy for repositioning this first-line antibiotic.

Gentamicin (GEN), a widely used broad-spectrum antibiotic, faces challenges amid the global emergency of antimicrobial resistance. This study aimed to explore the synergistic effects of zinc oxide nanoparticles (ZnO NPs) in combination with GEN on the bactericidal activity against various bacterial strains. Results showed ZnO NPs with MICs ranging from 0.002 to 1.5 µg/mL, while the precursor salt displayed a MIC range of 48.75-1560 µg/mL. Chitosan (CS)-capped ZnO NPs exhibited even lower MICs than their uncapped counterparts, with the CS-capped synthesized ZnO NPs demonstrating the lowest values. Minimal bactericidal concentrations (MBC) aligned with MIC trends. Combinations of CS-capped synthesized ZnO NPs and GEN proved highly effective, inhibiting bacterial growth at significantly lower concentrations than GEN or ZnO NPs alone. This phenomenon may be attributed to the conformation of CS on the ZnO NPs' surface, enhancing the positive particle surface charge. This possibly facilitates a more effective interaction between ZnO NPs and microorganisms, leading to increased accumulation of zinc and GEN within bacterial cells and an overproduction of reactive oxygen species (ROS). It's crucial to note that, while this study did not specifically involve resistant strains, its primary focus remains on enhancing the overall antimicrobial activity of gentamicin. The research aims to contribute to addressing the global challenge of antimicrobial resistance, recognizing the urgent need for effective strategies to combat this critical issue. The findings, particularly the observed synergy between ZnO NPs and GEN, hold significant implications for repositioning the first-line antibiotic GEN.

Live attenuated Mycobacterium bovis strains combined with the encapsulated H65 antigen as a vaccine strategy against bovine tuberculosis in a mouse model.

Mycobacterium bovis is an etiological agent of bovine tuberculosis (bTB) that also infects other mammals, including humans. The lack of an effective vaccine for the control of bTB highlights the need for developing new vaccines. In this study, we developed and evaluated an M. bovis strain deleted in the virulence genes phoP, esxA and esxB as a vaccine candidate against bTB in BALBc mice. The evaluated strains were the new live vaccine and BCG, alone or in combination with ncH65vD. The immunogen ncH65vD is a fusion protein H65, encapsulated together with vitamin D3, within the oily body of a nanocapsule composed of an antigen-loading polymeric shell. All vaccines conferred protection against the M. bovis challenge. However, no significant differences were detected among the vaccinated groups regarding bacterial loads in lungs and spleen. Mice vaccinated with the mutant strain plus ncH65vD showed negative Ziehl Neelsen staining of mycobacteria in their lungs, which suggests better control of bacteria replication according to this protection parameter. Consistently, this vaccination scheme showed the highest proportion of CD4 + T cells expressing the protection markers PD-1 and CXCR3 among the vaccinated groups. Correlation studies showed that PD-1 and CXCR3 expression levels in lung-resident CD4 T cells negatively correlated with the number of colony forming units of M. bovis in the lungs of mice. Therefore, the results suggest a link between the presence of PD-1 + and CXCR3 + cells at the site of the immune response against mycobacteria and the level of mycobacterial loads.

Magnetic layered double hydroxides with carbamazepine for breast cancer treatment.

Current cancer chemotherapy is associated with many side effects and, in some cases, drug resistance, which makes the search for new active molecules and drug delivery strategies imperative. Carbamazepine is an antiepileptic compound that has shown efficacy against breast cancer cell lines. In this study, it was incorporated into layered double hydroxide nanoclays, the percentage of drug loading was increased compared to previous research, and the clays were impregnated with magnetic Fe3O4 nanoparticles. The goal of the magnetic Fe3O4-impregnation was to direct the nanocomposites to the therapeutic target with an external magnetic field. The nanoclay-carbamazepine composites had a carbamazepine loading of 51 %, and the nanoclay-carbamazepine-nanoparticles had a drug loading of 13 % due to the addition of more ingredients. The structure of the composites was analyzed by X-ray diffraction and Scherrer equation, showing a layered double hydroxide organization with crystal sizes of 9-15 nm; from transmission electron microscopy, the final compounds showed a particle size of 97-158 nm, small enough for systemic circulation. In vibrating sample magnetization studies, the composites showed a superparamagnetic behavior with high magnetic saturation (9-17 emu/gr), which should allow a good material attraction by an external magnetic field located near the tumor. In vitro drug release studies were done in Franz cells and measured by UV/Vis spectrophotometry; they showed that carbamazepine release from the nanocomposites responds to the media pH: a good drug release at the lysosome pH and slow release at the blood pH. Finally, the efficacy was tested in vitro in MDA-MB-231 breast cancer cells, and the composites showed an enhanced efficacy in comparison with that produced by the free drug (96 % and 62 % of cell inhibition respectively). Carbamazepine administered with magnetic clays as a carrier is a promising treatment for breast cancer, and further studies should be done to measure the arrival time and the efficacy in vivo.

Cuprous oxide nanoparticles incorporated into a polymeric matrix embedded in fabrics to prevent spread of SARS-CoV-2.

This paper describes the development of a coating for cotton and polypropylene (PP) fabrics based on a polymeric matrix embedded with cuprous oxide nanoparticles (Cu2O@SDS NPs) in order to inactivate SARS-CoV-2 and manufactured by a simple process using a dip-assisted layer-by-layer technology, at low curing temperature and without the need for expensive equipment, capable of achieving disinfection rates of up to 99%. The polymeric bilayer coating makes the surface of the fabrics hydrophilic, enabling the transportation of the virus-infected droplets to achieve the rapid inactivation of SARS-CoV-2 by contact with the Cu2O@SDS NPs incorporated in the coated fabrics.

Exploring the Toxicity, Lung Distribution, and Cellular Uptake of Rifampicin and Ascorbic Acid-Loaded Alginate Nanoparticles as Therapeutic Treatment of Lung Intracellular Infections.

Nanotechnology is a very promising technological tool to combat health problems associated with the loss of effectiveness of currently used antibiotics. Previously, we developed a formulation consisting of a chitosan and tween 80-decorated alginate nanocarrier that encapsulates rifampicin and the antioxidant ascorbic acid (RIF/ASC), intended for the treatment of respiratory intracellular infections. Here, we investigated the effects of RIF/ASC-loaded NPs on the respiratory mucus and the pulmonary surfactant. In addition, we evaluated their cytotoxicity for lung cells in vitro, and their biodistribution on rat lungs in vivo after their intratracheal administration. Findings herein demonstrated that RIF/ASC-loaded NPs display a favorable lung biocompatibility profile and a uniform distribution throughout lung lobules. RIF/ASC-loaded NPs were mainly uptaken by lung macrophages, their primary target. In summary, findings show that our novel designed RIF/ASC NPs could be a suitable system for antibiotic lung administration with promising perspectives for the treatment of pulmonary intracellular infections.

Promising Chitosan-Coated Alginate-Tween 80 Nanoparticles as Rifampicin Coadministered Ascorbic Acid Delivery Carrier Against Mycobacterium tuberculosis.

The aim of this study was to design a nanocarrier system for inhalation delivery of rifampicin (RIF) in combination with ascorbic acid (ASC), namely constituted of sodium alginate coated with chitosan and Tween 80 (RIF/ASC NPs) as a platform for the treatment of pulmonary tuberculosis infection. A Box-Behnken experimental design and response surface methodology (RSM) were applied to elucidate and evaluate the effects of several factors on the nanoparticle properties. On the other hand, it was found that RIF/ASC NPs were less cytotoxic than the free RIF, showing a significantly improved activity against nine clinical strains of Mycobacterium tuberculosis (M. tb) in comparison with the free drug. RIF/ASC NPs had an average particle size of 324.0 ± 40.7 nm, a polydispersity index of 0.226 ± 0.030, and a zeta potential of - 28.52 ± 0.47 mV and the surface was hydrophilic. The addition of sucrose (1% w/v) to the nanosuspension resulted in the formation of a solid pellet easily redispersible after lyophilization. RIF/ASC NPs were found to be stable at different physiological pH values. In summary, findings of this work highlight the potential of the RIF/ASC NP-based formulation development herein to deliver RIF in combination with ASC through pulmonary route by exploring a non-invasive route of administration of this antibiotic, increasing the local drug concentrations in lung tissues, the primary infection site, as well as reducing the risk of systemic toxicity and hence improving the patient compliance.

Biosynthesized silver nanoparticles: Decoding their mechanism of action in Staphylococcus aureus and Escherichia coli.

The oxidative stress generation in bacteria by the presence of antibiotics (in this case silver nanoparticles (AgNPs)) is already widely known. Previously, we demonstrated that AgNPs generate oxidative stress in Staphylococcus aureus and Escherichia coli mediated by the increase of reactive oxygen species (ROS). In this work we are demonstrating the consequences of the oxidative stress by the presence of AgNPs; these bacterial strains increased the levels of oxidized proteins and lipids. In addition, it was possible to determine which reactive oxygen species are mainly responsible for the oxidative damage to macromolecules. Also, we found that the bacterial DNA was fragmented and the membrane potential was modified. This increase in the levels of ROS found in both, S. aureus and E. coli, was associated with the oxidation of different types of important macromolecules for the normal functioning of cell, so the oxidative stress would be one of the mechanisms by which the AgNPs would exert their toxicity in both strains, one Gram positive and the other Gram negative of great clinical relevance.

Effect of Complexes and Microemulsions on the Permeability of Drugs: Determination Using a New Biomimetic Artificial Membrane.

The aim of this work was to predict the permeability of two model drugs, sulfamerazine (SMR) and indomethacin (INM), and to determine the effect on their apparent permeabilities by complexation with cyclodextrins and/or meglumine or incorporation in microemulsions. Permeation experiments were performed using two-chamber diffusion cells with a new composition of bio-mimetic membrane composed of 80% of Lipoid® S100 and 20% of cholesterol in n-octanol 10% w/w solution, at 37 ± 0.5°C and 14,000 rpm. The predictive capacity of the permeability of passive diffusion absorbed compounds was evaluated using 20 drug standards and showed an exponential correlation between the apparent permeability coefficients (Papp) and the fraction absorbed percentages in humans (Fa%), with an R2 value of 0.67942 and a constant value of - 4.1 ± 0.8. SMR and INM were classified as Class II and I, respectively, according to the Biopharmaceutical Classification System. These drugs were complexed and incorporated in microemulsions. The Fa% from all the drug products was higher than 90%. SMR in the complexes and both drugs in microemulsions were classified as highly soluble. Thus, SMR and INM incorporated in these pharmaceutical products could be classified as Class I.

Comparative Oral Drug Classification Systems: Acetazolamide, Azithromycin, Clopidogrel, and Efavirenz Case Studies.

Biopharmaceutics classification systems based on the properties of solubility and permeability or the extension of metabolism are very important tools in the early stages of the development and regulatory stages of new products. However, until now, there was no clear understanding between the interplay among these classification systems. Therefore, the main objective of this work was to make a comparison of concepts of BCS and BDDCS to understand what are the key factors that allow for the integration of these biopharmaceutics classification systems. Also, the suitability of an in situ single-pass intestinal perfusion assay in rats (SPIP) development was assessed by us to determine the limit between high and low permeability following what the FDA BCS guidance suggests. An excellent correlation was found between the values of permeability obtained by applying SPIP assays and the extensions of the metabolism of the set of compounds studied in this work, with the exception of three compounds that showed disparity between their permeability coefficients ( Peff), obtained herein by SPIP, and their metabolism (acetazolamide, azithromycin, and efavirenz). Discrepancies allowed us to elucidate the interrelationship between BCS and BDDCS.

Use of microreactors and freeze-drying in the manufacturing process of chitosan coated PCL nanoparticles.

This paper is focused on the synthesis of chitosan-coated polycaprolactone nanoparticles in microreactors and on the freeze-drying of the nanosuspension, to separate the particles from the liquid phase. Nanoparticles were produced in the confined impinging jets mixer (CIJM) and in the multi-inlet vortex mixer (MIVM), using the solvent displacement method, with acetone or tert-butanol (TBA) as polymer solvent. The study was initially carried out considering a feed flow rate of 80 ml min-1: using acetone, the mean particle size was lower (163 ±â€¯7 nm) and the Zeta potential was higher (31.4 ±â€¯37 mV) with the MIVM, with respect to the CIJM (265 ±â€¯31 nm and 9.8 ±â€¯2.4 mV, respectively). Slightly larger particles were obtained using TBA in the MIVM (mean diameter: 221 ±â€¯44 nm): in this case it is no longer required removing the solvent before the freeze-drying stage. The effect of the liquid flow rate was then investigated, confirming that the best results were obtained at 80 ml min-1. With respect to the freeze-drying process, the effect of lyoprotectants and of steric stabilizers on particle stability was investigated. Best results were obtained with 5% sucrose and 2.5% Poloxamer 388 (mean diameter: 306 ±â€¯8 nm); in all cases Zeta potential remained positive and larger than +30 mV. Preliminary results about the encapsulation of a test drug, ciprofloxacin, are also shown and discussed.

Artificial Lipid Membrane Permeability Method for Predicting Intestinal Drug Transport: Probing the Determining Step in the Oral Absorption of Sulfadiazine; Influence of the Formation of Binary and Ternary Complexes with Cyclodextrins.

We propose an in vitro permeability assay by using a modified lipid membrane to predict the in vivo intestinal passive permeability of drugs. Two conditions were tested, one with a gradient pH (pH 5.5 donor/pH 7.4 receptor) and the other with an iso-pH 7.4. The predictability of the method was established by correlating the obtained apparent intestinal permeability coefficients (Papp) and the oral dose fraction absorbed in humans (fa) of 16 drugs with different absorption properties. The Papp values correlated well with the absorption rates under the two conditions, and the method showed high predictability and good reproducibility. On the other hand, with this method, we successfully predicted the transport characteristics of oral sulfadiazine (SDZ). Also, the tradeoff between the increase in the solubility of SDZ by its complex formation with cyclodextrins and/or aminoacids and its oral permeability was assessed. Results suggest that SDZ is transported through the gastrointestinal epithelium by passive diffusion in a pH-dependent manner. These results support the classification of SDZ as a high/low borderline permeability compound and are in agreement with the Biopharmaceutics Classification Systems (BCS). This conclusion is consistent with the in vivo pharmacokinetic properties of SDZ.

Cross-linked hyaluronan films loaded with acetazolamide-cyclodextrin-triethanolamine complexes for glaucoma treatment.

AIM: This work aimed to design and characterize cross-linked hyaluronic acid-itaconic acid films loaded with acetazolamide-hydroxypropyl ß cyclodextrin-triethanolamine complexes. MATERIALS & METHODS: Films were cross-linked with itaconic acid and poly(ethyleneglycol)-diglycidylether. Biopharmaceutical properties were assessed by evaluating in vitro drug release rate, biocompatibility in a human corneal epithelial cell line, bioadhesiveness with pig gastric mucin, in vivo bioadhesion and efficacy. RESULTS: Showed good mechanical properties and oxygen permeability. Proliferation rate of corneal cells was affected by highest acetazolamide concentration. Bioadhesive interaction exhibited a water movement from pig mucin to the film; in vivo experiments showed strong bioadhesion for 8 h and hypotensive effect for almost 20 h. CONCLUSION: Experimental set showed promising performance and encouraged future studies to optimize formulation. [Formula: see text].

On the Production of Chitosan-Coated Polycaprolactone Nanoparticles in a Confined Impinging Jet Reactor.

This work is focused on the synthesis of polycaprolactone nanoparticles, coated with chitosan, in a confined impinging jet reactor using the solvent displacement method. The role of the various reacting species was investigated, evidencing that a biocompatible polymer, for example, polycaprolactone, is required to support chitosan to obtain a monomodal particle size distribution, with low particle diameters. A surfactant is required to reduce the nanoparticle size (down to a mean diameter of about 260 nm) and obtain a positive zeta potential (about +31 mV), perfectly suitable for pharmaceutical applications. Different surfactants were tested, and Poloxamer 388 appeared to be preferable to polyvinyl alcohol. The effect of the concentration of Poloxamer 388 (in the range 0.5-5 mg mL-1) and of chitosan (in the range 1.5-5 mg mL-1) on both the mean particle size and zeta potential was also investigated, evidencing that chitosan concentration has the strongest effect on both parameters. Finally, the effect of solvent evaporation, quenching and feed flow rate was investigated, showing that the evaporation stage does not affect particle characteristics, quenching is required to avoid particle aggregation, and a minimum liquid flow rate of 80 mL min-1 is required in the considered reactor to minimize the particle size.

Partition of Amphiphilic Molecules to Lipid Bilayers by ITC: Low-Affinity Solutes.

A protocol is developed to allow the accurate characterization of partition to lipid bilayers for solutes with low affinity, using isothermal titration calorimetry. The methodology proposed is suitable for studies using complex membranes, such as intact biomembranes or whole cells. In the method developed, the association is characterized at increasing solute concentrations. This allows the characterization of solute partition into unperturbed membranes, as well as effects induced by high solute concentrations. Most druglike molecules are expected to interact with low-to-moderate affinity with relevant cell membranes. This is due to both the need for a relatively high aqueous solubility of the drug and the poor binding properties of the cell membranes. The methodology is applied to characterize the interaction of antibiotic Rifampicin with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and with lipid bilayers representative of bacterial membranes.

Studies of ternary systems of sulfadiazine with Beta-cyclodextrin and aminoacids / Estudios de sistemas ternarios de sulfadiazina con Beta-ciclodextrina y aminoácidos

Introduction: Cyclodextrins (CD), are known to form inclusion complexes with a variety of guest molecules both in solution and in the solid state. This can lead to the alteration of properties of guest molecules. Unfortunately, the complexation efficiency of CD is rather low, and can be enhanced by formation of ternary complexes using aminoacids (AA). Sulfadiazine (SDZ) is an antibiotic with extremely low water solubility which limits its therapeutic applications and bioavailability. Objetives: The aim of this work was to increase the aqueous solubility of SDZ by preparing ternary complexes of this drug with β-cyclodextrin (βCD) and an AA as a third auxiliary substance. Materials y Methods: Complex formation was studied by phase solubility analysis (PSA), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and scanning electron microscopy (SEM). Results: The apparent stability constants (KC) of the multicomponent complexes were calculated from the solubility diagrams. By the analysis of the NMR spectra, it could be said that the shifts of some protons evidenced the important role of the AA in the formation of multicomponent complexes. Among the AA, Arginine (ARG) proved to have better solubilizing properties for SDZ, reaching an improvement up to 70 times. The use of DSC, TG and SEM suggested the formation of new solid phases between SDZ:βCD:AA. Conclusions: As a result of this research, it was determined that ternary products were more effective in improving drug solubility than the corresponding SDZ:βCD binary system

Introducción: Las ciclodextrinas (CD), son capaces de formar complejos de inclusión con una variedad de moléculas huésped, tanto en solución y en estado sólido, pudiendo producir la modificación de las propiedades de las moléculas huésped. Desafortunadamente, la eficiencia de la formación de complejos con CD es baja, lo cual se puede mejorar mediante la formación de complejos ternarios utilizando aminoácidos (AA). Sulfadiazina (SDZ) es un antibiótico con muy baja solubilidad en agua que limita su biodisponibilidad y sus aplicaciones terapéuticas. Objetivos: El objetivo de este trabajo fue aumentar la solubilidad acuosa de SDZ mediante la preparación de complejos ternarios con β-ciclodextrina (βCD) y un AA como una tercera sustancia. Materiales y Métodos: La formación de complejos se estudió por análisis de solubilidad de fases (PSA), resonancia magnética nuclear (RMN), calorimetría diferencial de barrido (DSC), análisis termogravimétrico (TG) y microscopía electrónica de barrido (SEM). Resultados: Las constantes de estabilidad aparente (KC) de los complejos multi-componentes se calcularon a partir de los diagramas de solubilidad. Por el análisis de los espectros de RMN se constató, por los corrimientos de algunos protones, el papel importante de los AA en la formación de complejos ternarios. Entre los AA, arginina (ARG) demostró tener mejores propiedades de solubilización para SDZ, alcanzando una mejora de hasta 70 veces. El uso de DSC, TG y SEM sugirió la formación de nuevas fases sólidas entre SDZ:βCD:AA

Targeted chitosan-based bionanocomposites for controlled oral mucosal delivery of chlorhexidine.

The purpose of this study was to develop sustained release systems based on chitosan (CS) and montmorillonite (MMT) for chlorhexidine (CLX). Nanocomposites were prepared by ion-exchange. CLX systems were characterized by X-ray powder diffraction (XRD), thermal analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRF). The mucoadhesion properties of CLX nanocomposites were evaluated by SEM. The release behavior of these systems was also studied by the dialysis technique. The antibacterial activity was investigated in vitro by the disk diffusion test. Results showed long-term sustained release of CLX from the hybrid carriers without initial burst release. The release profiles of CLX from the carriers suggested the diffusion through a swollen matrix and water filled pores as the controlled drug release mechanism. The CLX hybrid nanosystem containing the positively-charged chitosan exhibited good mucoadhesion properties maintaining the CLX antimicrobial properties.

Intestinal uptake and toxicity evaluation of acetazolamide and its multicomponent complexes with hidroxypropyl-ß-cyclodextrin in rats.

Large oral doses of ACZ lower the intraocular pressure (IOP), but usually lead to a multitude of systemic side effects, including gastrointestinal upset. The present study was undertaken to evaluate the effect of ACZ on the histological structure of rat duodenal mucosa and to assess a possible protective role of the complex formation of ACZ with HP-ß-CD, either separately or in combination with a third compound, on the gut epithelial layer by histological and ultrastructural examinations of sections of rat duodenum exposed to ACZ or its formulations. In addition, the transport process of ACZ and its binary or ternary complexes across the duodenal mucosa by means of the single-pass intestinal perfusion (SPIP) method in rats was evaluated. Evidence was found that ACZ alters intestinal permeability and induces damage to the rat small intestine. In contrast, ACZ-induced intestinal injury may be abrogated by ACZ complexation. In addition, the complexation of ACZ with HP-ß-CD, alone or in combination with a third compound, facilitated significant levels of ACZ uptake across the rat duodenal segment. Ternary complexes of ACZ with HP-ß-CD in combination with TEA (triethanolamine) or calcium ions were found to provide an excellent approach that enabled an increased apparent permeability of ACZ across the duodenal epithelium, with a concomitant ability to preserve the integrity of the gut epithelium from ACZ-induced injury. These results could be useful for the design and development of novel ACZ formulations that can reduce GI toxicity, while still maintaining their essential therapeutic efficacies.

Rate of vision loss in neovascular age-related macular degeneration explored.

PURPOSE: To explore decline in visual acuity in patients with neovascular age-related macular degeneration (n-AMD) awaiting intravitreal bevacizumab or ranibizumab treatment following initial diagnosis and after disease reactivation. METHODS: Retrospective analysis of 74 treatment-naïve patients (84 eyes) in two centers in Córdoba, Argentina. The time between treatment indication and intravitreal injection, and the changes in BCVA produced during this delay were studied in both periods. A linear regression model to search the impact of time on progression visual impairment was conducted. RESULTS: In both periods, a significant reduction in vision occurred awaiting intravitreal injection. The longer the delay, the greater the vision loss (R2 = 0.55 p < 0.01) and the less improvement following treatment (Pearson coefficient -0.26). The result of the model shows that the change in vision as a function of initial delay were best described by a polynomic model with a mean loss of 5 letters in the first 3 weeks, a slowdown in the rate of change of VA, and a dependence of visual acuity at the moment of diagnosis . The loss of visual acuity after reactivation shows the same behavior as at the onset of the disease but independent of visual acuity prior to reactivation. CONCLUSION: Visual loss awaiting injection intravitreal anti-VEGF is clinically significant and with an asymptotic pattern, with early rapid loss of vision in both the onset of the disease and the reactivation. Initiation of anti-VEGF treatment must be undertaken urgently, as should retreatment of disease activation to reduce visual loss.

Characterization, dissolution and in vivo evaluation of solid acetazolamide complexes.

The effects of binary and ternary systems of acetazolamide (ACZ) with hydroxypropyl-ß-cyclodextrin (HP-ß-CD) alone or with triethanolamine (TEA) on the crystalline properties, dissolution and intraocular pressure (IOP)-lowering effect were investigated. It was found that the crystal structure of ACZ powder could be modified by the processing conditions. Freeze-drying ACZ powder affected not only the particle morphology but also its polymorphic form and the starting ACZ was converted to pure form A upon freeze-drying treatment. Results provided by DSC/TGA, XRPD, SEM and FT-IR suggested the formation of inclusion complexes between ACZ with HP-ß-CD alone or with TEA, obtained by the freeze-drying method and the conversion of the drug into the amorphous state. Binary and ternary systems of ACZ obtained by freeze-drying exhibited significantly enhanced ACZ dissolution rates. The IOP-lowering effects of ACZ and its complexes with HP-ß-CD alone or with TEA were studied in normotensive rabbits. Whereas the maximum IOP-lowering effect (~4 mmHg, ~33%), obtained with these binary and ternary lyophilized ACZ systems occurred at around 90 min, the ternary system exhibited a longer maximum IOP-lowering effect peak compared with that of the binary system. These results are in line with those obtained from the dissolution studies, where the ternary system exhibited longer dissolution times compared to the lyophilized binary one. Results obtained from the dissolution studies, also showed that freeze-drying the native crystalline form of ACZ significantly increased the dissolution rate of ACZ, thus improving the IOP-lowering effect of this drug.