Development of albendazole sulfoxide-loaded Eudragit microparticles: A potential strategy to improve the drug bioavailability

Albendazole sulfoxide (ABZSO), a broad spectrum anthelmintic drug extensively used in veterinary medicine, exhibits a low and erratic bioavailability due to its poor solubility in biological fluids. The aims of this study were the development, physicochemical characterization, and in vitro release profile evaluation of ABZSO-loaded Eudragit RS PO (R) microparticles (MPs) in order to improve the rate of dissolution and the dissolved percentage of the drug in pH 7.4. MPs were successfully obtained by the emulsification/solvent evaporation method, achieving entrapment efficiency and process yield of about 60% and mean size of 254 nm. The in vitro release profile study showed that dissolution of ABZSO followed a pseudo-second order kinetics and MPs were able to increase significantly (p < 0.05) the rate of dissolution of ABZSO compared to the micronized and non-micronized free drug, what could lead to an improvement in bioavailability and, consequently, in the antiparasitic activity. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Antimycobacterial activity of 2-phenoxy-1-phenylethanone, a synthetic analogue of neolignan, entrapped in polymeric microparticles

Conventional treatment of tuberculosis (TB) demands a long course therapy (6 months), known to originate multiple drug resistant strains (MDR-TB), which emphasizes the urgent need for new antituberculous drugs. The purpose of this study was to investigate a novel treatment for TB meant to improve patient compliance by reducing drug dosage frequency. Polymeric microparticles containing the synthetic analogue of neolignan, 1-phenyl-2-phenoxiethanone (LS-2), were obtained by a method of emulsification and solvent evaporation and chemically characterized. Only representative LS-2-loaded microparticles were considered for further studies involving experimental murine TB induced by Mycobacterium tuberculosis H37Rv ATCC 27294. The LS-2-loaded microparticles were spherical in shape, had a smooth wall and showed an encapsulation efficiency of 93% in addition to displaying sustained release. Chemotherapeutic potential of LS-2 entrapped in microparticles was comparable to control groups. These findings are encouraging and indicate that LS-2-loaded microparticles are a potential alternative to conventional chemotherapy of TB.

Vesicles as carriers of virulence factors in parasitic protozoan diseases

Different types of shed vesicles as, for example, exosomes, plasma-membrane-derived vesicles or microparticles, are the focus of intense research in view of their potential role in cell cell communication and under the perspective that they might be good tools for immunotherapy, vaccination or diagnostic purposes. This review discusses ways employed by pathogenic trypanosomatids to interact with the host by shedding vesicles that contain molecules important for the establishment of infection, as opposed to previous beliefs considering them as a waste of cellular metabolism. Trypanosomatids are compared with Apicomplexa, which circulate parasite antigens bound to vesicles shed by host cells. The knowledge of the origin and chemical composition of these different vesicles might lead to the understanding of the mechanisms that determine their biological function. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Effects of the particle sizes and concentrations on the X-ray absorption by CuO compounds

This work presents a study on the effects of the particle size, material concentration and radiation energy on the X-ray absorption. CuO nanoparticles and microparticles were incorporated separately into a polymeric resin in concentrations of 5%, 10% and 30% relative to the resin mass. X-ray absorption by these materials was analyzed with a CdTe detector. The X-ray absorption is higher for the nanostructured material compared to the microstructured one for low energy X-ray beams for all CuO concentrations. (c) 2011 Elsevier Ltd. All rights reserved.

Titanium dioxide induced inflammation in the small intestine

AIM: To investigate the effects of titanium dioxide (TiO2) nanoparticles (NPTiO2) and microparticles (MPTiO2) on the inflammatory response in the small intestine of mice. METHODS: BI 57/6 male mice received distilled water suspensions containing TiO2 (100 mg/kg body weight) as NPTiO2 (66 nm), or MPTiO2 (260 nm) by gavage for 10 d, once a day; the control group received only distilled water. At the end of the treatment the duodenum, jejunum and ileum were extracted for assessment of cytokines, inflammatory cells and titanium content. The cytokines interleukin (IL)-1b, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17, IL-23, tumor necrosis factor-alpha (TNF-alpha), intracellular interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) were evaluated by enzyme-linked immunosorbent assay in segments of jejunum and ileum (mucosa and underlying muscular tissue). CD4(+) and CD8(+) T cells, natural killer cells, and dendritic cells were evaluated in duodenum, jejunum and ileum samples fixed in 10% formalin by immunohistochemistry. The titanium content was determined by inductively coupled plasma atomic emission spectrometry. RESULTS: We found increased levels of T CD4(+) cells (cells/mm(2)) in duodenum: NP 1240 +/- 139.4, MP 1070 +/- 154.7 vs 458 +/- 50.39 (P < 0.01); jejunum: NP 908.4 +/- 130.3, MP 813.8 +/- 103.8 vs 526.6 +/- 61.43 (P < 0.05); and ileum: NP 818.60 +/- 123.0, MP 640.1 +/- 32.75 vs 466.9 +/- 22.4 (P < 0.05). In comparison to the control group, the groups receiving TiO2 showed a statistically significant increase in the levels of the inflammatory cytokines IL-12, IL-4, IL-23, TNF-alpha, IFN-gamma and TGF-beta. The cytokine production was more pronounced in the ileum (mean SE): IL-12: NP 33.98 +/- 11.76, MP 74.11 +/- 25.65 vs 19.06 +/- 3.92 (P < 0.05); IL-4: NP 17.36 +/- 9.96, MP 22.94 +/- 7.47 vs 2.19 +/- 0.65 (P < 0.05); IL-23: NP 157.20 +/- 75.80, MP 134.50 +/- 38.31 vs 22.34 +/- 5.81 (P < 0.05); TNF alpha: NP 3.71 +/- 1.33, MP 5.44 +/- 1.67 vs 0.99 +/- 019 (P < 0.05); IFN gamma: NP 15.85 +/- 9.99, MP 34.08 +/- 11.44 vs 2.81 +/- 0.69 (P < 0.05); and TGF-alpha: NP 780.70 +/- 318.50, MP 1409.00 +/- 502.20 vs 205.50 +/- 63.93 (P < 0.05). CONCLUSION: Our findings indicate that TiO2 particles induce a Th1-mediated inflammatory response in the small bowel in mice. (C) 2012 Baishideng. All rights reserved.

Spray Congealing of Pharmaceuticals: Study on Production of Solid Dispersions Using Box-Behnken Design

This work aimed at evaluating the spray congealing method for the production of microparticles of carbamazepine combined with a polyoxylglyceride carrier. In addition, the influence of the spray congealing conditions on the improvement of drug solubility was investigated using a three-factor, three-level Box-Behnken design. The factors studied were the cooling air flow rate, atomizing pressure, and molten dispersion feed rate. Dependent variables were the yield, solubility, encapsulation efficiency, particle size, water activity, and flow properties. Statistical analysis showed that only the yield was affected by the factors studied. The characteristics of the microparticles were evaluated using X-ray powder diffraction, scanning electron microscopy, differential scanning calorimetry, and hot-stage microscopy. The results showed a spherical morphology and changes in the crystalline state of the drug. The microparticles were obtained with good yields and encapsulation efficiencies, which ranged from 50 to 80% and 99.5 to 112%, respectively. The average size of the microparticles ranged from 17.7 to 39.4 mu m, the water activities were always below 0.5, and flowability was good to moderate. Both the solubility and dissolution rate of carbamazepine from the spray congealed microparticles were remarkably improved. The carbamazepine solubility showed a threefold increase and dissolution profile showed a twofold increase after 60 min compared to the raw drug. The Box-Behnken fractional factorial design proved to be a powerful tool to identify the best conditions for the manufacture of solid dispersion microparticles by spray congealing.

Microparticulated Hydrochlorothiazide Solid Dispersion: Enhancing Dissolution Properties via Spray Drying

The aim of the present study was to obtain microparticles of hydrochlorothiazide, a diuretic drug that practically insoluble in water, by spray drying and to investigate the influence of process parameters using a three-level, three-factor Box-Behnken design. Process yields, moisture content, particle size, flowability, and solubility were used to evaluate the spray-dried microparticles. The data were analyzed by response surface methodology using analysis of variance. The independent variables studied were outlet temperature, atomization pressure, and drug content. The formulations were prepared using polyvinylpyrrolidone and colloidal silicon dioxide as the hydrophilic carrier and drying aid, respectively. The microparticle yield ranged from 18.15 to 59.02% and resulted in adequate flow (17 to 32 degrees), moisture content between 2.52 to 6.18%, and mean particle size from 45 to 59 mu m. The analysis of variance showed that the factors studied influenced the yields, moisture content, angle of repose, and solubility. Thermal analysis and X-ray diffractometry evidenced no drug interactions or chemical modifications. Photomicrographs obtained by scanning electron microscopy showed spherical particles. The solubility and dissolution rates of hydrochlorothiazide were remarkably improved when compared with pure drug. Therefore, the results confirmed the high potential of the spray-drying technique to obtain microparticulate hydrochlorothiazide with enhanced pharmaceutical and dissolution properties.

Protection of Bifidobacterium lactis and Lactobacillus acidophilus by microencapsulation using spray-chilling

The aim of this study was to produce and evaluate solid lipid microparticles containing Bifidobacterium lactis or Lactobacillus acidophilus. Survival assays were conducted to evaluate the resistance of the probiotics to spray-chilling process, their resistance to simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) and their stability during 90 d of storage. The viability of the cells was not affected by microencapsulation. The free and encapsulated cells of B. lactis were resistant to SGF and SIF. The microencapsulation, however, provided protection for L. acidophilus against SGF and SIF. The free and encapsulated microorganisms lost their viability when they were stored at 37 degrees C. However, promising results were obtained when refrigerated and frozen storage was applied. The study indicates that spray-chilling using fat as carrier can be considered an innovative technology and matrix, respectively, for the protection, application and delivery of probiotics. (C) 2012 Elsevier Ltd. All rights reserved.

Microencapsulation of Ketoprofen in Blends of Acrylic Resins by Spray Drying

Microparticles of ketoprofen entrapped in blends of acrylic resins (Eudragit RL 30D and RS 30D) were successfully produced by spray drying. The effects of the proportion ketoprofen : polymer (1: 1 and 1: 3) and of spray-drying parameters (drying gas inlet temperatures of 80 and 100 degrees C; microencapsulating composition feed flow rates of 4 and 6 g/min) on the microparticles properties (drug content, encapsulation efficiency, mean particle size, moisture content, and dissolution behavior) were evaluated. Differential scanning calorimetry (DSC) thermograms and X-ray diffractograms of the spray-dried product, the free drug, and the physical mixture between the free drug and spray-dried composition (blank) were carried out. Microparticles obtained at inlet temperature of 80 degrees C, feed flow rate of 4 g/min, and ketoprofen : acrylic resin ratio of 1: 3 presented an encapsulation efficiency of 88.1%, moisture content of 5.8%, production yield around 50%, and a higher reduction in dissolution rate of the entrapped ketoprofen. Sigmoidal shape dissolution profiles were presented by the spray-dried microparticles. The dissolution profiles were relatively well described by the Weibull model, a showing high coefficient of determination, R-2, and a mean absolute error between experimental and estimated values of between 4.6 and 10.1%.

Microstructured ternary solid dispersions to improve carbamazepine solubility

The aim of this study was to investigate the improvement of the aqueous solubility of carbamazepine by preparing microstructured ternary solid dispersions using polyoxylglycerides and colloidal silicon dioxide. Microstructured solid dispersions were obtained in a spray dryer. The influence of the spray drying conditions on the properties of the microparticles was investigated using a full 3(2) factorial design in which the factors studied were the silicon dioxide content and the air outlet temperature. The microparticles were thoroughly characterized in terms of yield, solubility, angle of repose, particle size, drug content, moisture content, sorption isotherms, morphology, thermal behavior, infrared spectroscopy and crystallinity. The dissolution rates of carbamazepine and of the microparticles in water were also determined. In general, the microstructured solid dispersions demonstrated good yield, adequate flow and moisture content (<3%), drug recovery (91.98 to 100.22%) and particle size (<142.90 mu m). Thermal and infrared analysis showed that there was no drug interaction during the process. On the other hand, the results of X-ray diffraction evidenced a partial polymorphic modification of carbamazepine. The solubility and dissolution rates of carbamazepine were remarkably improved. Therefore, the results confirm the high potential of the spray drying technique to obtain microstructured ternary solid dispersions. (C) 2011 Elsevier B.V. All rights reserved.

Engineering Active Pharmaceutical Ingredients by Spray Drying: Effects on Physical Properties and In Vitro Dissolution

Active pharmaceutical ingredients have very strict quality requirements; minor changes in the physical and chemical properties of pharmaceuticals can adversely affect the dissolution rate and therefore the bioavailability of a given drug. Accordingly, the aim of the present study was to investigate the effect of spray drying on the physical and in vitro dissolution properties of four different active pharmaceutical ingredients, namely carbamazepine, indomethacin, piroxicam, and nifedipine. Each drug was dispersed in a solution of ethanol and water (70:30) and subjected to single-step spray drying using similar operational conditions. A complete characterization of the spray-dried drugs was performed via differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), particle size distribution analysis, solubility analysis, and an in vitro dissolution study. The results from the thermal analysis and X-ray diffraction showed that, except for carbamazepine, no chemical modifications occurred as a result of spray drying. Moreover, the particle size distribution of all the spray-dried drugs significantly decreased. In addition, SEM images showed that most of the particles had an irregular shape. There was no significant improvement in the solubility of the spray-dried drugs compared with the unprocessed compounds; however, in general, the dissolution rates of the spray-dried drugs showed a remarkable improvement over their non-spray-dried counterparts. Therefore, the results from this study demonstrate that a single spray-drying step may lead to changes in the physical properties and dissolution characteristics of drugs and thus improve their therapeutic action.

PLGA microspheres containing bee venom proteins for preventive immunotherapy

Bee venom (BV) allergy is potentially dangerous for allergic individuals because a single bee sting may induce an anaphylactic reaction, eventually leading to death. Currently, venom immunotherapy (VIT) is the only treatment with long-lasting effect for this kind of allergy and its efficiency has been recognized worldwide. This therapy consists of subcutaneous injections of gradually increasing doses of the allergen. This causes patient lack of compliance due to a long time of treatment with a total of 30-80 injections administered over years. In this article we deal with the characterization of different MS-PLGA formulations containing BV proteins for VIT. The PLGA microspheres containing BV represent a strategy to replace the multiple injections, because they can control the solute release. Physical and biochemical methods were used to analyze and characterize their preparation. Microspheres with encapsulation efficiencies of 49-75% were obtained with a BV triphasic release profile. Among them, the MS-PLGA 34 kDa-COOH showed to be best for VIT because they presented a low initial burst (20%) and a slow BV release during lag phase. Furthermore, few conformational changes were observed in the released BV. Above all, the BV remained immunologically recognizable, which means that they could continuously stimulate the immune system. Those microspheres containing BV could replace sequential injections of traditional VIT with the remarkable advantage of reduced number of injections. (C) 2011 Elsevier B.V. All rights reserved.

Platelet-derived exosomes induce endothelial cell apoptosis through peroxynitrite generation: experimental evidence for a novel mechanism of septic vascular dysfunction

Abstract Introduction Several studies link hematological dysfunction to severity of sepsis. Previously we showed that platelet-derived microparticles from septic patients induce vascular cell apoptosis through the NADPH oxidase-dependent release of superoxide. We sought to further characterize the microparticle-dependent vascular injury pathway. Methods During septic shock there is increased generation of thrombin, TNF-α and nitric oxide (NO). Human platelets were exposed for 1 hour to the NO donor diethylamine-NONOate (0.5 μM), lipopolysaccharide (LPS; 100 ng/ml), TNF-α (40 ng/ml), or thrombin (5 IU/ml). Microparticles were recovered through filtration and ultracentrifugation and analyzed by electron microscopy, flow cytometry or Western blotting for protein identification. Redox activity was characterized by lucigenin (5 μM) or coelenterazine (5 μM) luminescence and by 4,5-diaminofluorescein (10 mM) and 2',7'-dichlorofluorescein (10 mM) fluorescence. Endothelial cell apoptosis was detected by phosphatidylserine exposure and by measurement of caspase-3 activity with an enzyme-linked immunoassay. Results Size, morphology, high exposure of the tetraspanins CD9, CD63, and CD81, together with low phosphatidylserine, showed that platelets exposed to NONOate and LPS, but not to TNF-α or thrombin, generate microparticles similar to those recovered from septic patients, and characterize them as exosomes. Luminescence and fluorescence studies, and the use of specific inhibitors, revealed concomitant superoxide and NO generation. Western blots showed the presence of NO synthase II (but not isoforms I or III) and of the NADPH oxidase subunits p22phox, protein disulfide isomerase and Nox. Endothelial cells exposed to the exosomes underwent apoptosis and caspase-3 activation, which were inhibited by NO synthase inhibitors or by a superoxide dismutase mimetic and totally blocked by urate (1 mM), suggesting a role for the peroxynitrite radical. None of these redox properties and proapoptotic effects was evident in microparticles recovered from platelets exposed to thrombin or TNF-α. Conclusion We showed that, in sepsis, NO and bacterial elements are responsible for type-specific platelet-derived exosome generation. Those exosomes have an active role in vascular signaling as redox-active particles that can induce endothelial cell caspase-3 activation and apoptosis by generating superoxide, NO and peroxynitrite. Thus, exosomes must be considered for further developments in understanding and treating vascular dysfunction in sepsis.