Since 1966, rifampicin (RIF) has been considered one of the most potent drugs in the treatment of tuberculosis (TB), which is caused by infection with M. tuberculosis (Mtb). New nanostructured formulations for RIF delivery and alternative... more
Since 1966, rifampicin (RIF) has been considered one of the most potent drugs in the treatment of tuberculosis (TB), which is caused by infection with M. tuberculosis (Mtb). New nanostructured formulations for RIF delivery and alternative routes of administration have been studied as potential forms of treatment. This study evaluates a liquid crystal system for RIF delivery, using alternative drug delivery routes. The systems developed are composed of surfactant, oleylamine, and soy phosphatidylcholine. With the aid of polarized light microscopy, it was possible to determine that the developed systems had a hexagonal mesophase. All systems developed showed non-Newtonian pseudoplasticity and a high degree of thixotropy. Liquid crystal systems with RIF showed an increase in elastic potential, indicating greater mu-coadhesiveness. The evaluation of mucoadhesive forces revealed an increase in the mucoadhesive potential in the presence of mucus, indicating the presence of satisfactory mu...
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One of the challenges to the success of veterinary pharmacotherapy is the limited number of drugs and dosage forms available exclusively to this market, due to the interspecies variability of animals, such as anatomy, physiology,... more
One of the challenges to the success of veterinary pharmacotherapy is the limited number of drugs and dosage forms available exclusively to this market, due to the interspecies variability of animals, such as anatomy, physiology, pharmacokinetics, and pharmacodynamics. For this reason, studies in this area have become a highlight, since they are still scarce in comparison with those on human drug use. To overcome many limitations related to the bioavailability, efficacy, and safety of pharmacotherapy in animals, especially livestock and domestic animals, polymers-based drug delivery systems are promising tools if they guarantee greater selectivity and less toxicity in dosage forms. In addition, these tools may be developed according to the great interspecies variability. To contribute to these discussions, this paper provides an updated review of the major polymer-based drug delivery systems projected for veterinary use. Traditional and innovative drug delivery systems based on polymers are presented, with an emphasis on films, microparticles, micelles, nanogels, nanoparticles, tablets, implants and hydrogel-based drug delivery systems. We discuss important concepts for the veterinarian about the mechanisms of drug release and, for the pharmacist, the advantages in the development of pharmaceutical forms for the animal population. Finally, challenges and opportunities are presented in the field of pharmaceutical dosage forms for veterinary use in response to the interests of the pharmaceutical industry.
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Introducao: O desenvolvimento de sistemas matriciais multiparticulados, constituidos por polimeros hidrofilicos, especificamente degradados pela microbiota colonica ou com solubilidade pH dependente, como a goma gelana (GG) e a pectina e... more
Introducao: O desenvolvimento de sistemas matriciais multiparticulados, constituidos por polimeros hidrofilicos, especificamente degradados pela microbiota colonica ou com solubilidade pH dependente, como a goma gelana (GG) e a pectina e uma estrategia racional para a vetorizacao de farmacos para o colon. A capacidade de absorcao de liquidos de matrizes polimericas e uma importante propriedade a ser avaliada, pois e um processo diretamente relacionado a eventos como a mucoadesao, a dissolucao e a degradacao enzimatica. Objetivo: Avaliar a capacidade de absorcao de liquido, de microesferas, em meios com diferentes valores de pH (1,2 e 7,4). Metodologia: Microesferas foram obtidas pelo metodo de geleificacao ionotropica. Dispersoes de goma gelana:pectina (G:P) 2 ou 3% na proporcao 1:1 e 4:1, contendo resveratrol (0,25 ou 0,5%), foram gotejadas em solucao de Al3+ (3 e 5%, 4oC) com seringa e agulha sem bisel (0,6 x 25 mm). As particulas formadas foram mantidas sob agitacao (45 ou 90 min...
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Introducao: O desenvolvimento de sistemas multiparticulados, como as microesferas (MEs),baseados em polimeros naturais como a goma gelana (GG) e pectina (P) representa uma estrategia racional e inovadora para a administracao de... more
Introducao: O desenvolvimento de sistemas multiparticulados, como as microesferas (MEs),baseados em polimeros naturais como a goma gelana (GG) e pectina (P) representa uma estrategia racional e inovadora para a administracao de quimioterapicos, destinados ao tratamento do câncer colorretal. Tais sistemas podem permitir a administracao oral dessa classe de farmacos alem de a associacao da GG e P, que apresentam propriedade mucoadesiva e degradacao especifica pela microbiota colonica, serem capazes de vetorizar a liberacao do farmaco no local onde encontra-se o tumor, tornando a terapia mais especifica. Objetivo:Obtencao de MEspela tecnica de geleificacao ionotropica e avaliacao da influencia da solucao reticulante (Ca2+ ou Al3+)e do diâmetro da agulhano diâmetro e circularidade das particulas.Metodologia: Uma dispersao aquosa (3%, m/v) da mistura de GG:P(1:1, m/m), sob agitacao magnetica e aquecimento foi preparada. Apos, a dispersaofoi gotejada com auxilio de seringa e agulha (23G 1...
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Two samples of N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan (DPCat) with different average degrees of quaternization named as DPCat35 (DQ¯ = 35%) and DPCat80 (DQ¯ = 80%), were successfully synthesized by reacting... more
Two samples of N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan (DPCat) with different average degrees of quaternization named as DPCat35 (DQ¯ = 35%) and DPCat80 (DQ¯ = 80%), were successfully synthesized by reacting glycidyltrimethylammonium chloride (GTMAC) with O-palmitoyl chitosan (DPCh) derivative (DS¯ = 12%). Such amphiphilic derivatives of chitosan were fully water-soluble at 1.0 < pH < 12.0 and showed significant electrostatic stability enhancement of a self-assembly micellar nanostructure (100-320 nm) due to its positively-charged out-layer. In vitro mucoadhesive and cytotoxicity essays toward human healthy fibroblast cells (Balb/C 3T3 clone A31 cell), prostate cancer (DU145) and liver cancer (HepG2/C3A) cell lines revealed that the biological properties of DPCat derivatives were strongly dependent on DQ¯. Additionally, DPCat35 had better interactions with the biological tissue and with mucin glycoproteins at pH 7.4 as well as exhibited potential to be used on the development of drug delivery systems for prostate and liver cancer treatment.
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The design of mucoadhesive drug delivery systems (DDS) based on polysaccharides at nanoscale or microscale is a relevant technological strategy for the mucosal delivery of several drugs. Findings about the potential mucoadhesive ability... more
The design of mucoadhesive drug delivery systems (DDS) based on polysaccharides at nanoscale or microscale is a relevant technological strategy for the mucosal delivery of several drugs. Findings about the potential mucoadhesive ability of these materials, and the mechanisms that drive such interactions represents an important advance for the rational modulation of such properties, according specific therapeutic needs. The potential mucoadhesive abilities of gellan gum (GG) and retrograded starch (RS) were investigated at pH 1.2 and 6.8, which were considered biorrelevant for the gastrointestinal tract (GIT). The effects of these polysaccharides on the MUC rheology were also addressed. Rheological studies revealed high MUC-GG interactions at both pH values (1.2 and 6.8), expressing a high mucoadhesive ability, mainly in acidic media. MUC-GG interactions were driven, mainly, by hydrogen bonds. At an acidic pH, significant changes occurred in the MUC arrangements due to the strong MUC-GG interactions, as corroborated by scanning electron microscopy (SEM). The rheological behavior of MUC-RS indicated poor interactions between them and MUC arrangements were more preserved as evidenced by SEM. The results of this work indicate that the mixing of GG and RS can be a promising strategy to modulate mucoadhesiveness of DDS, according to specific therapeutic needs.
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Anti-vascular endothelial growth factor (anti-VEGF) therapy applied to solid tumors is a promising strategy, yet, the challenge to deliver these agents at high drug concentrations together with the maintenance of therapeutic doses... more
Anti-vascular endothelial growth factor (anti-VEGF) therapy applied to solid tumors is a promising strategy, yet, the challenge to deliver these agents at high drug concentrations together with the maintenance of therapeutic doses locally, at the tumor site, minimizes its benefits. To overcome these obstacles, we propose the development of a bevacizumab-loaded alginate hydrogel by electrostatic interactions to design a delivery system for controlled and anti-angiogenic therapy under tumor microenvironmental conditions. The tridimensional hydrogel structure produced provides drug stability and a system able to be introduced as a flowable solution, stablishing a depot after local administration. Biological performance by the chick embryo chorioallantoic membrane (CAM) assay indicated a pH-independent improved anti-angiogenic activity (∼50%) compared to commercial available anti-VEGF drug. Moreover, there was a considerable regression in tumor size when treated with this system. Immuno...
Research Interests: Chemistry, Drug delivery, Medicine, Angiogenesis, Drug, and 15 moreTumor microenvironment, Humans, Animals, Drug Delivery Systems, Alginates, Science Technology, Neoplasms, Bevacizumab, Drug Carriers, Antineoplastic Agents, Chorioallantoic Membrane, Supramolecular Interactions, Angiogenesis inhibitors, Chick embryo, and Pharmacology and pharmaceutical sciences
From previous studies, it has been found that curcumin exhibits an anti-inflammatory activity and is being used for the treatment of skin disorders; however, it is hydrophobic and has weak penetrating ability, resulting in poor drug... more
From previous studies, it has been found that curcumin exhibits an anti-inflammatory activity and is being used for the treatment of skin disorders; however, it is hydrophobic and has weak penetrating ability, resulting in poor drug transport through the stratum corneum. The aim of this study was to develop liquid crystalline systems for topical administration of curcumin for the treatment of inflammation. These liquid crystalline systems were developed from oleic acid, polyoxypropylene (5) polyoxyethylene (20) cetyl alcohol, and water as the surfactant, oil phase, and aqueous phase, respectively. These systems were characterized, and polarized light microscopy showed anisotropy with lamellar mesophases (Formulation 1) and hexagonal mesophases (Formulations 2 and 3), which were confirmed by the peak ratio measured using small-angle X-ray scattering. In addition, rheological tests revealed that the formulations exhibited gel-like behavior (G'>G″), as evidenced by the increased...
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New biocompatible nanomaterials are leading to a range of emerging health treatments. Thus, peptide drugs present in oral diseases, such as caries, periodontal diseases and oral cancer, are highlighting into clinical practice because the... more
New biocompatible nanomaterials are leading to a range of emerging health treatments. Thus, peptide drugs present in oral diseases, such as caries, periodontal diseases and oral cancer, are highlighting into clinical practice because the peptides can have an influence the growth of tumor cells or microorganisms and its can exhibit direct cytotoxic activity towards cancer cells or microbial cells. Therefore, it is interesting to speculate what are the natural or synthetic peptides that can be used to develop novel strategies to fight cancer diseases or microbial cells, and so, to represent a novel family of anticancer or antimicrobial agents. The use of buccal drug delivery systems, especially nanoparticles, to carrier peptides shows to be very interesting, because these systems can protect the peptide against enzymatic degradation, in addition to target inaccessible sites. However, this peptide delivery system seems to be unexplored by researchers. On the hand, the application of drug delivery systems for oral diseases could be a proposed treatment for these diseases, including the treatment or co-treatment with other therapies, such as photodynamic therapy, of antimicrobial, periodontal diseases and cancer, or even in the early diagnosis of cancer. The objective of this study is to present a systematic review of nanotechnology-based peptides delivery systems intended to oral diseases.
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ABSTRACT This work aims to develop and validate a simple methodology to quantify the most used antiretroviral, zidovudine (AZT), in rat plasma for preclinical studies. Some assays have been previously reported to quantify AZT in plasma;... more
ABSTRACT This work aims to develop and validate a simple methodology to quantify the most used antiretroviral, zidovudine (AZT), in rat plasma for preclinical studies. Some assays have been previously reported to quantify AZT in plasma; however, the majority of these methods uses complicated extraction methods. This method uses only 100 �µL plasma samples, which were precipitated with 100 �µL acidified acetonitrile containing an internal standard (IS). The plasma extracts were injected directly in a chromatographic system consisting of a UV–Vis detector (set at 266 nm) and an RP-C18 column. The mobile phase was an isocratic mixture of acetonitrile, methanol and 0.01% v/v aqueous formic acid (20:20:60 v/v/v) at a flow rate of 0.8 mL/min. Intra- and inter-day assay precision and accuracy variability were lower than 20% for the limit of quantification and 15% for higher concentrations. The applicability of the method was demonstrated by an in vivo study performed in rats. They were treated orally with an AZT-containing syrup and intravenously with an AZT solution. The calculated bioavailability of the syrup (56.7%) was in accordance with the literature. Therefore, this method can be used as an alternative to quantify plasma AZT in preclinical studies.
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A simple, rapid, accurate and sensitive method was developed for quantitative analysis of dexamethasone acetate in microemulsions using high performance liquid chromatography (HPLC) with UV detection. The chromatography parameters were... more
A simple, rapid, accurate and sensitive method was developed for quantitative analysis of dexamethasone acetate in microemulsions using high performance liquid chromatography (HPLC) with UV detection. The chromatography parameters were stainless steel Lichrospher 100 RP-18 column (250 mm x 4 mm i.d., 5 μm particle size), at 30 ± 2 ºC. The isocratic mobile phase was methanol:water (65:35; v/v) at a flow rate of at 1.0 mL.min-1. The determinations were performed using UV-Vis detector set at 239 nm. Samples were prepared with methanol and the volume injected was 20 μL. The analytical curve was linear (r² 0.9995) over a wide concentration range (2.0-30.0 μg.mL-1). The presence of components of the microemulsion did not interfere in the results of the analysis. The method showed adequate precision, with a relative standard deviation (RSD) smaller than 3%. The accuracy was analyzed by adding a standard drug and good recovery values were obtained for all drug concentrations used. The HPLC ...
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... THALITA PEDRONI FORMARIZ1 LUIGINA JOANA SPERA1 MARIA CRISTINA COCENZA URBAN1 PRISCILA DE OLIVEIRA CINTO1 MARIA PALMIRA DAFLON ... couro cabeludo, conduto auditivo exter-no, regiões atrás das orelhas, sombrancelhas, cílios e barba;... more
... THALITA PEDRONI FORMARIZ1 LUIGINA JOANA SPERA1 MARIA CRISTINA COCENZA URBAN1 PRISCILA DE OLIVEIRA CINTO1 MARIA PALMIRA DAFLON ... couro cabeludo, conduto auditivo exter-no, regiões atrás das orelhas, sombrancelhas, cílios e barba; além da ...
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Abstract Supramolecular design refers to the application of supramolecular chemistry concepts and tools to the development of drug delivery systems. The approach is explored in this chapter in the context of nanomanipulation of... more
Abstract Supramolecular design refers to the application of supramolecular chemistry concepts and tools to the development of drug delivery systems. The approach is explored in this chapter in the context of nanomanipulation of polymer-based systems. Fundamental aspects of supramolecular interactions are discussed, focusing on their importance to the fabrication of hydrophobic and hydrophilic nanoparticles. Specific discussion explores the self-assembly process of polymer building blocks in polymeric nanoparticles and the main tools and techniques used to monitor synthetic procedures and characterize physicochemical properties. The chapter ends with the major challenges that should be addressed to optimize self-assembly for rational design of polymer-based nanoparticles.
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Drug actions can be improved by developing new drug delivery systems, such as the mucoadhesive system. These systems remain in close contact with the absorption tissue, the mucous membrane, releasing the drug at the action site leading to... more
Drug actions can be improved by developing new drug delivery systems, such as the mucoadhesive system. These systems remain in close contact with the absorption tissue, the mucous membrane, releasing the drug at the action site leading to a bioavailability increase and both local and systemic effects. Mucoadhesion is currently explained by six theories: electronic, adsorption, wettability, diffusion, fracture and mechanical. Several in vitro and in vivo methodologies are proposed for studying its mechanisms. However, mucoadhesion is not yet well understood. The aim of this study was to review the mechanisms and theories involved in mucoadhesion, as well as to describe the most-used methodologies and polymers in mucoadhesive drug delivery systems.
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A hydrogel was developed from 70 kDa dextran (DEX-70) and praziquantel (PZQ) incorporated as a model drug. Biopharmaceutical properties, such as solubility and dissolution rate, were analysed in the design of the hydrogel. Furthermore,... more
A hydrogel was developed from 70 kDa dextran (DEX-70) and praziquantel (PZQ) incorporated as a model drug. Biopharmaceutical properties, such as solubility and dissolution rate, were analysed in the design of the hydrogel. Furthermore, the hydrogel was also characterized by IR spectroscopy and DSC. Tests of the swelling rate showed that the hydrogel swelled slowly, albeit faster than the rate for the free polymer. In dissolution tests, the hydrogel released the drug slowly and continuously. This slow release was similar to that observed in the swelling tests and resulted in controlled release of the drug. Thus, this dextran is a suitable polymer for the development of hydrogels as vehicles for the controlled release of drugs.
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This review discusses basic aspects used to control the architecture and functional properties of smart hydrogels. The introduction briefly outlines what has been accomplished regarding smart hydrogels and explores historical aspects and... more
This review discusses basic aspects used to control the architecture and functional properties of smart hydrogels. The introduction briefly outlines what has been accomplished regarding smart hydrogels and explores historical aspects and the fundamental understanding of these systems. Then, a short discussion on the chemical interactions and the main variables involved in architectural construction is exhibited. Further analysis provides the basis for optimizing biological responses through system modulation. Finally, we outline perspectives and challenges for building smart hydrogels into functionalized and modulated delivery systems.
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Mucoadhesive nanoparticles are particularly interesting for delivery through nasal or pulmonary routes, as an approach to overcome the mucociliary clearance. Moreover, these nanoparticles are attractive for peptide and protein delivery,... more
Mucoadhesive nanoparticles are particularly interesting for delivery through nasal or pulmonary routes, as an approach to overcome the mucociliary clearance. Moreover, these nanoparticles are attractive for peptide and protein delivery, particularly for insulin to treat diabetes, as an alternative to conventional parenteral administration. Thus, chitosan, a cationic mucoadhesive polysaccharide found in shells of crustaceans, and the negatively-charged dextran sulfate are able to form nanoparticles through ionic condensation, representing a potential insulin carrier. Herein, chitosan/dextran sulfate nanoparticles at various ratios were prepared for insulin loading. Formulations were characterized for particle size, zeta potential, encapsulation efficiency, scanning electron microscopy, differential scanning calorimetry, and in vitro drug release. Moreover, the interaction with mucin and the cytotoxicity against a lung cell line were studied, which altogether have not been addressed b...
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Nanotechnology offers advantages for new drug delivery design by providing drug targeting while minimizing the side effects. Polyoxyethylene 20 cetyl alcohol (CETETH-20) is a surfactant that may form nanostructured systems, such as liquid... more
Nanotechnology offers advantages for new drug delivery design by providing drug targeting while minimizing the side effects. Polyoxyethylene 20 cetyl alcohol (CETETH-20) is a surfactant that may form nanostructured systems, such as liquid crystals, when in contact with water/oil, which are structurally similar to biological membranes and may improve skin interaction. The aim of this study was to develop and characterize CETETH 20-based nanostructured systems by combining CETETH-20 with water and different oily phases, including PEG-12-dimethicone for topical drug administration. The systems were characterized by polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), rheology, texture profile analyses (TPA), in vitro cytotoxicity and histopathological analyses of rabbits&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; skin. Lamellar, hexagonal and cubic phases were identified and their viscoelastic moduli varied according to each phase. The stiffness of the cubic phase was 3-fold higher and twice more adhesive than the hexagonal phase. The formulations did not affect the normal macrophages cells, neither promoted skin irritation. They were spontaneously obtained by simply mixing the components, which corroborates for an ease scaled-up. These results suggest that systems composed of CETETH 20, PEG-12-dimethicone and water are a promising new approach for designing nanostructured topical drug delivery systems.
Research Interests: Engineering, Technology, Nanoparticles, Cell line, Mice, and 15 moreAnimals, Male, Skin, CHEMICAL SCIENCES, Topical Drug Administration, Emulsions, Surface Active Agents, Oleic Acid, Rabbits, Fatty Alcohols, Drug Carriers, Silicones, Cell Survival, Polyethylene Glycols, and Nanoscience and nanotechnology
Hyperproliferative skin diseases (HSD) are a group of diseases that include cancers, pre-cancerous lesions and diseases of unknown etiology that present different skin manifestations in terms of the degree and distribution of the... more
Hyperproliferative skin diseases (HSD) are a group of diseases that include cancers, pre-cancerous lesions and diseases of unknown etiology that present different skin manifestations in terms of the degree and distribution of the injuries. Anti-proliferative agents used to treat these diseases are so diverse, including 5-aminolevulinic acid, 5-fluorouracil, imiquimod, methotrexate, paclitaxel, podophyllotoxin, realgar, and corticosteroids in general. These drugs usually have low aqueous solubility, which consequently decreases skin permeation. Thus, their incorporation in lipid nanocarriers has been proposed with the main objective to increase the effectiveness of topical treatment and reduce side effects. This manuscript aims to describe the advantages of using lipid nanoparticles and liposomes that can be used to load diversity of chemically different drugs for the treatment of HSD.
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Insulin is an important anabolic hormone that regulates the metabolism of carbohydrates, lipids and proteins. In this study, a reverse-phase liquid chromatography (RP-LC) method was successfully validated and tested for the encapsulation... more
Insulin is an important anabolic hormone that regulates the metabolism of carbohydrates, lipids and proteins. In this study, a reverse-phase liquid chromatography (RP-LC) method was successfully validated and tested for the encapsulation efficiency assay of insulin and in vitro release studies. HPLC analyses were carried out using a RP C18- Luna® Phenomenex (4.6 × 250 mm, 5 μm particle size) column maintained at room temperature, using a mobile phase constituted by a mixture of acetonitrile and 0.1% TFA aqueous solution (60:40, v/v), in an isocratic mode with a flow rate of 1.0 mL/min, with ultraviolet detection at 214 nm and 20 μL of injection volume. Method validation was performed according recognized guidelines for system suitability, specificity, linearity, precision, accuracy, LOD, LOQ and robustness. The method was shown to be linear in the range of 0.5–100 μg/mL (r2 = 0.9993) selective, precise, robust, accurate with LOD and LOQ values were 0.097 μg/mL and 0.294 μg/mL, respe...
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Polymer blends of gellan gum (GG)/retrograded starch(RS) and GG/pectin (P) were cross-linked with calcium, aluminum, or both to prepare mucoadhesive microparticles as oral carriers of drugs or nano systems. Cross-linking with different... more
Polymer blends of gellan gum (GG)/retrograded starch(RS) and GG/pectin (P) were cross-linked with calcium, aluminum, or both to prepare mucoadhesive microparticles as oral carriers of drugs or nano systems. Cross-linking with different cations promoted different effects on each blend, which can potentially be explored as novel strategies for modulating physical–chemical and mucoadhesive properties of microparticles. Particles exhibited spherical shapes, diameters from 888 to 1764 µm, and span index values lower than 0.5. Blends of GG:P cross-linked with aluminum resulted in smaller particles than those obtained by calcium cross-linking. GG:RS particles exhibited larger sizes, but cross-linking this blend with calcium promoted diameter reduction. The uptake rates of acid medium were lower than phosphate buffer (pH 6.8), especially GG:RS based particles cross-linked with calcium. On the other hand, particles based on GG:P cross-linked with calcium absorbed the highest volume of acid m...
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Metronidazole (MT) is an important drug available for Helicobacter pylori infection treatment. However, in the past few years, this drug has presented effective reduction for infection control, one of the most important reasons is... more
Metronidazole (MT) is an important drug available for Helicobacter pylori infection treatment. However, in the past few years, this drug has presented effective reduction for infection control, one of the most important reasons is attributed to the reduction of retention time in the stomach environment. Mucoadhesive nanostructured polyelectrolyte complexes (nano PECs) based on chitosan (CS) and hypromellose phthalate (HP) were rationally developed using a full factorial design (21 × 21 × 31), for the incorporation of MT based on the enhancement of the antimicrobial potential against active Helicobacter pylori, in the stomach. Different mass ratios of CS:HP (w/w) were tested, reaching the most promising ratios of 1:0.1, 1:0.5, and 1:1, and two methods of polymers addition (pouring-I and drip-II) were also evaluated. From method I, the obtained particles presented a diameter in the range of 811–1293 nm (Z-average) and a polydispersity index (PDI) between 0.47 and 0.88. By method II, t...
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This work aimed to develop a calcium alginate hydrogel as a pH responsive delivery system for polymyxin B (PMX) sustained-release through the vaginal route. Two samples of sodium alginate from different suppliers were characterized. The... more
This work aimed to develop a calcium alginate hydrogel as a pH responsive delivery system for polymyxin B (PMX) sustained-release through the vaginal route. Two samples of sodium alginate from different suppliers were characterized. The molecular weight and M/G ratio determined were, approximately, 107 KDa and 1.93 for alginate_S and 32 KDa and 1.36 for alginate_V. Polymer rheological investigations were further performed through the preparation of hydrogels. Alginate_V was selected for subsequent incorporation of PMX due to the acquisition of pseudoplastic viscous system able to acquiring a differential structure in simulated vaginal microenvironment (pH 4.5). The PMX-loaded hydrogel (hydrogel_PMX) was engineered based on polyelectrolyte complexes (PECs) formation between alginate and PMX followed by crosslinking with calcium chloride. This system exhibited a morphology with variable pore sizes, ranging from 100 to 200 μm and adequate syringeability. The hydrogel liquid uptake abil...
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Mucoadhesive drug delivery systems have been widely investigated as a strategic to allow the raising of intestinal residence time of drugs and the intimate contact with the intestinal mucosa, both factors that increase the local... more
Mucoadhesive drug delivery systems have been widely investigated as a strategic to allow the raising of intestinal residence time of drugs and the intimate contact with the intestinal mucosa, both factors that increase the local concentration gradient. Zidovudine (AZT) mucoadhesive nanostructured polyelectrolyte complexes were obtained by chitosan (CS)-hypromellose phthalate (HP) interactions in order to favor the permeability through biological membranes and the AZT absorption. Particle size and morphology analyses showed the obtaining of nanoparticulate delivery systems, with AZT loaded about of 65%. The characterization by DSC, X-ray diffraction and FTIR showed a new crystalline structure formed in which the drug remained molecularly dispersed, without changing this structure. The reduced release rates in the simulated gastric medium and the control of release rates in simulated intestinal medium of AZT were demonstrated by in vitro release studies. The nanoparticles liquid uptake ability associated to the mucoadhesiveness by electronic interaction between the particles and mucus revealed that the drug delivery system developed in this work is a promising approach to improve the permeation of this drug throughout the intestinal mucosa.
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Zidovudine (AZT) is the antiretroviral drug most frequently used for the treatment of Acquired Immunodeficiency Syndrome. Its low oral bioavailability demands the development of innovative strategies to overcome the first pass metabolism.... more
Zidovudine (AZT) is the antiretroviral drug most frequently used for the treatment of Acquired Immunodeficiency Syndrome. Its low oral bioavailability demands the development of innovative strategies to overcome the first pass metabolism. The nasal route is an option for enhanced therapeutic efficacy and to reduce the extent of the first-pass effect. In this article, AZT loaded chitosan nanoparticles were prepared by a modified ionotropic gelation method with sodium tripolyphosphate. The increase proportion of CS (NP1 10:01 (w/w)) promoted the formation of smaller nanoparticles (260 nm), while raising the proportion of TPP (NP2 5:1 w/w) increased the nanoparticles size (330 nm). The incorporation of AZT increased the nanoparticles size for both AZT-loaded nanoparticles AZT-loaded NP1 (406 nm) and AZT-loaded NP2 (425 nm). The incorporation of AZT into NP1 did not change the electrophoretic mobility, however, in AZT-loaded NP2 there was a significant increase. The positive surface of ...
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Anticardiolipin antibodies from sera of patients with systemic lupus erythematosus or syphilis induced leakage of entrapped carboxyfluorescein (CF) from cardiolipin (CL)/phosphatidylcholine(PC) vesicles prepared by sonication of equimolar... more
Anticardiolipin antibodies from sera of patients with systemic lupus erythematosus or syphilis induced leakage of entrapped carboxyfluorescein (CF) from cardiolipin (CL)/phosphatidylcholine(PC) vesicles prepared by sonication of equimolar mixtures of CL:PC. The sera dilution used here was 1:7500. IgG (5-20 micrograms/ml) from the same sera, not containing beta 2GPI, also produced a concentration-dependent leak. Vesicle leakage was inhibited by salt and was not detected with vesicles prepared exclusively with phosphatidylcholine. The demonstration of antibody-induced vesicle leakage offers a convenient system to investigate the mechanism of antibody-lipid binding as well as a potential diagnostic tool.