Triclosan resistance reversion by encapsulation in chitosan-coated-nanocapsule containing α-bisabolol as core: development of wound dressing.

The use of nanoparticles may be particularly advantageous in treating bacterial infections due to their multiple simultaneous mechanisms of action. Nanoencapsulation is particularly useful for lipophilic drugs. In this scenario, triclosan is considered a good candidate due to its lipophilicity, broad-spectrum activity, and safety. In the present study, we have developed and characterized an antimicrobial suspension of triclosan and α-bisabolol against pathogenic strains that are resistant (Pseudomonas aeruginosa) and susceptible (Escherichia coli, Staphylococcus aureus, and Candida albicans) to triclosan. We also aimed to determine the minimum inhibitory concentration, using serial microdilution adapted from a CLSI methodology (Clinical and Laboratory Standards Institute). Challenge test was used to confirm the antimicrobial effectiveness of the nanocapsule formulation, as well as after its incorporation into a commercial wound dressing (Veloderm®). The zeta potential of P. aeruginosa before and after contact with cationic nanocapsules and the ratio between the number of nanocapsules per colony forming unit (CFU) were determined to evaluate a possible interaction between nanocapsules and bacteria. The results showed that nanoencapsulation has improved the antimicrobial activity when tested with two different methodologies. The number of nanocapsules per CFU was high even in great dilutions and the zeta potential was reverted after being in contact with the cationic nanocapsules. The nanocapsules were able to improve the activity of triclosan, even when tested within 28 days and when dried in the wound dressing.

Effects of chitosan-coated lipid-core nanocapsules on bovine sperm cells.

Toxicology studies have a pivotal role for selection of new nanosystems. As lipid-core nanocapsules (LNC) rise as a potential system not only for drug delivery but also for immunotherapy and gene therapy, the demand for models of toxic screening increases, and sperm arises as a promising model due to the easiness to evaluate its viability parameters. LNCs were coated with chitosan, chitosan-coated lipid-core nanocapsules (LNC-CS), in order to modify the nanocapsule surface. We evaluated the toxicity of LNC and LNC-CS after incubation with bovine sperm in different concentrations (2.5%, 5%, 10%, 20%, 40% and 80%) (v/v) and periods of exposure (0h and 1h). CASA parameters and flow cytometry assays were performed to assess LNC and LNC-CS effects. The results corroborated with previous studies indicating that there is no toxicity from LNCs and LNC-CS below 40% (v/v) concentration.

Caenorhabditis elegans as an alternative in vivo model to determine oral uptake, nanotoxicity, and efficacy of melatonin-loaded lipid-core nanocapsules on paraquat damage.

Caenorhabditis elegans is an alternative in vivo model that is being successfully used to assess the pharmacological and toxic effects of drugs. The exponential growth of nanotechnology requires the use of alternative in vivo models to assess the toxic effects of theses nanomaterials. The use of polymeric nanocapsules has shown promising results for drug delivery. Moreover, these formulations have not been used in cases of intoxication, such as in treatment of paraquat (PQ) poisoning. Thus, the use of drugs with properties improved by nanotechnology is a promising approach to overcome the toxic effects of PQ. This research aimed to evaluate the absorption of rhodamine B-labeled melatonin (Mel)-loaded lipid-core nanocapsules (LNC) by C. elegans, the application of this model in nanotoxicology, and the protection of Mel-LNC against PQ damage. The formulations were prepared by self-assembly and characterized by particle sizing, zeta potential, drug content, and encapsulation efficiency. The results demonstrated that the formulations had narrow size distributions. Rhodamine B-labeled Mel-LNC were orally absorbed and distributed in the worms. The toxicity assessment of LNC showed a lethal dose 50% near the highest dose tested, indicating low toxicity of the nanocapsules. Moreover, pretreatment with Mel-LNC significantly increased the survival rate, reduced the reactive oxygen species, and maintained the development in C. elegans exposed to PQ compared to those worms that were either untreated or pretreated with free Mel. These results demonstrated for the first time the uptake and distribution of Mel-LNC by a nematode, and indicate that while LNC is not toxic, Mel-LNC prevents the effects of PQ poisoning. Thus, C. elegans may be an interesting alternative model to test the nanocapsules toxicity and efficacy.

In vivo gastroprotective effect of nanoparticles: influence of chemical composition and volume fraction.

In nanomedicine, different nanomaterials and nanoparticles have been proposed as therapeutic agents or adjuvants, as well as diagnosis devices. Considering that the principal cause of the ulcerations is the imbalance among the gastric juice secretion and the protection provided by the mucosal barrier and the neutralization of the gastric acid, as well as that nanoparticles are able to accumulate in the gastro-intestinal tissues, we proposed a 2(2) factorial design to evaluate the influence of the chemical composition and the volume fraction of the dispersed phase on the gastric protective effect against ulceration induced by ethanol. Cocoa-theospheres (CT) and lipid-core nanocapsules (LNC) (two different kinds of surfaces: lipid and polymeric, respectively) prepared at two different concentrations of soft materials: 4% and 12% (w/v) were produced by high pressure homogenization and solvent displacement methods, respectively. Laser diffraction showed volume-weighted mean diameters ranging from 133 to 207 nm, number median diameters lower than 100 nm and specific surfaces between 41.2 and 51.2 m(2) g(-1). The formulations had pH ranging from 4.7 to 6.3; and zeta potential close to -9 mV due to their coating with polysorbate 80. The ulcer indexes were 0.40 (LNC(4)) and 0.48 (CT(4)) for the lower total administered areas (3.3 and 4.1 m(2)g(-1), respectively), and 0.09 (LNC(12) and CT(12)) for the higher administered areas (10.0 and 12.0 m(2) g(-1), respectively). LNC(4), LNC(12) and CT(12) showed lower levels in the lipid peroxidation assay when compared either to the negative control (saline) or to CT(4). LNC(12) and CT(12) showed similar TBARS levels, as well as CT(4) was similar to the negative control. SEM analysis of the stomach mucosa showed coatings more homogenous and cohesive when LNC formulations were administered compared to the correspondent CT formulations. The higher total area of administered nanoparticles showed film formation. Moreover, LNC(12) provided a more thick and cohesive film, completely covering the mucosal surface. In conclusion, both kinds of formulations are able to prevent ulceration induced by ethanol in rats. The 2(2) factorial design showed that the chemical composition had a strong influence when the lower areas of nanoparticles are administered, while when the higher areas are used this is the more influencing parameter on the gastroprotection.

Vitamin K1-loaded lipid-core nanocapsules: physicochemical characterization and in vitro skin permeation.

BACKGROUND: The incorporation of substances in nanocarriers can modulate and/or manage their delivery profiles (immediate or sustained) and permeation through skin. Consequently, drug nanencapsulation intended for topical treatment can reduce the systemic absorption of the substance. OBJECTIVE: To obtain and characterize vitamin K1-loaded lipid core nanocapsules as well as to determine whether the nanoencapsulation influences the skin permeation of this vitamin. METHODS: The skin permeation study was performed by means of Franz-type diffusion cells followed by the tape stripping and retention techniques. The vitamin K1-loaded lipid core nanocapsules were obtained by the preformed polymer precipitation method and the particles were characterized. RESULTS: The nanocapsules presented average diameter of 211 ± 2 nm, pH of 5.7 ± 0.3, zeta potential of -14.9 ± 0.6 mV and drug content of 10.2 mg/mL (102.1%). The physical stability of the nanocapsule suspension was verified using multiple light backscattering analysis. The amount of vitamin K1 in the dermis after 8 h of drug permeation was higher when the nanocapsules were applied compared to the control. Moreover, retention in the outermost skin layer and a decrease in the skin permeation to the receptor compartment due to the nanoencapsulation were observed. CONCLUSION: Thus, nanoencapsulation can lead to the selective permeation of vitamin K1 through the skin.

Agglomerates containing pantoprazole microparticles: modulating the drug release.

Pantoprazole-loaded microparticles were prepared using a blend of Eudragit S100 and Methocel F4M. The accelerated stability was carried out during 6 months at 40 degrees C and 75% relative humidity. In order to improve technological characteristics of the pantoprazole-loaded microparticles, soft agglomerates were prepared viewing an oral delayed release and gastro-resistant solid dosage form. The agglomeration was performed by mixing the pantoprazole microparticles with spray-dried mannitol/lecithin powders. The effects of factors such as the amount of lecithin in the spray-dried mannitol/lecithin powders and the ratio between pantoprazole microparticles and spray-dried mannitol/lecithin powders were evaluated. The pantoprazole-loaded microparticles present no significant degradation in 6 months. The agglomerates presented spherical shape, with smooth surface and very small quantity of non-agglomerated particles. The agglomerates presented different yields (35.5-79.0%), drug loading (58-101%), and mechanical properties (tensile strength varied from 44 to 69 mN mm(-2)), when the spray-dried mannitol/lecithin powders with different lecithin amounts were used. The biopharmaceutical characteristics of pantoprazole microparticles, i.e., their delayed-release properties, were not affected by the agglomeration process. The gastro-resistance of the agglomerates was affected by the amount of spray-dried mannitol/lecithin powders. The ratio of lecithin in the spray-dried mannitol/lecithin powders was the key factor in the agglomerate formation and in the drug release profiles. The agglomerates presenting better mechanical and biopharmaceutical characteristics were prepared with 1:2 (w/w) ratio of pantoprazole-loaded microparticles and mannitol/lecithin (80:20) powder.

Incorporation in polymeric nanocapsules improves the antioxidant effect of melatonin against lipid peroxidation in mice brain and liver.

It has been recently shown that the association of melatonin with polymeric nanoparticles causes a significant increase of the in vitro effect against lipid peroxidation. Hence, the aim of the present study was to compare the in vivo acute antioxidant effect of intraperitoneal administration of melatonin-loaded polysorbate 80-coated nanocapsules with that of melatonin aqueous solution in mice brain (frontal cortex and hippocampus) and liver. The lipid peroxidation through thiobarbituric acid reactive substance levels, the total antioxidant reactivity (luminol-enhanced chemiluminescence) and the free radical levels (formed dichlorofluorescein) has been carried out. Our results show that a single melatonin aqueous solution injection exerted no antioxidant activity in the evaluated range, while the administration of the melatonin-loaded polysorbate 80-coated nanocapsules caused a marked reduction on lipid peroxidation levels in all studied tissues. No differences on free radical content were found in the tissues. The melatonin-loaded nanocapsules also increased the total antioxidant reactivity in the hippocampus. These in vivo results are in accordance with our previous in vitro findings and confirm the hypothesis that polymeric nanocapsules improve the antioxidant effect of melatonin against lipid peroxidation.

Sodium pantoprazole-loaded enteric microparticles prepared by spray drying: effect of the scale of production and process validation.

Pantoprazole is a prodrug used in the treatment of acid related disorders and Helicobacter pylori infections. It is activated inside gastric parietal cells binding irreversibly to the H(+)/K(+)-ATPase. In this way, pantoprazole must be absorbed intact in the intestinal tract, which indicates that enteric drug delivery systems are required for its oral administration. The purpose of this study was to investigate the physical characteristics of enteric pantoprazole-loaded microparticles prepared by spray drying using a blend of Eudragit S100 and HPMC. The microparticles were produced in different spray dryers and operational conditions at laboratory and pilot scales. Microparticles produced with two fluid nozzle atomizer and air pressure of 196 kPa presented satisfactory encapsulation efficiency and gastro-resistance. Microparticles produced with the same atomizer but using 49 kPa of air pressure presented strings in the powder. The microparticles produced in mixed flow presented very high polydispersity and the ones produced with rotating disc atomizer presented drug crystals adsorbed on the particle surfaces. The microparticles produced with two fluid nozzle atomizer and 196 kPa were prepared in three consecutive days for the process validation. The powders showed reproducible diameter, polydispersity, densities, encapsulation efficiency and gastro-resistance profile.