Nanocarriers with gentamicin to treat intracellular pathogens.

Brucellosis is a worldwide zoonosis caused by different species of the genus Brucella. The intracellular localisation of this pathogen, particularly in macrophages, renders treatment difficult since most antibiotics known to be efficient in vitro do not actively pass through cellular membranes. As alternative to current treatment, polymeric drug delivery systems containing gentamicin have been developed. These particulate carriers target the drug into the mononuclear-phagocytic system, where the pathogen resides that will allow intracellular accumulation of the antibiotic after particle degradation. Besides, particle uptake may induce macrophage activation, increasing the production of reactive oxygen intermediates, involved in host defense against the intracellular pathogen. The aim of the present work was to study the suitability of polymeric nanoparticles for gentamicin entrapment in view to treat brucellosis. Different poly(lactide-co-glycolide) PLGA polymers were used to formulate the nanoparticles containing gentamicin by a water-oil-water solvent evaporation method. Furthermore, in vitro macrophage activation upon nanoparticles phagocytosis and in vivo distribution of the nanocarriers in the target organs for Brucella (liver and spleen) were also studied. The nanoparticle sizes were below 350 nm, the gentamicin encapsulation efficiency depended on the polymer type used for their preparation and the in vitro release of the antibiotic exhibited a continuos pattern (PLGA 502H). PLGA 502H nanoparticles were the most suitable due to the highest entrapment and the most sustained release. The nanoparticles were successfully phagocyted by a J774 murine monocytes cell line and biodistribution studies in mice after intravenous administration of the delivery systems revealed that the particles reached the target organs of Brucella (liver and spleen). All together, these results indicate that the nanocarriers described in this work may be suitable as gentamicin delivery system to control brucellosis.

In vitro evaluation of gentamicin released from microparticles.

In this study, the preparation, characterization and drug release behaviour of gentamicin (GM)-loaded poly(D,L-lactide-co-glycolide) microspheres are described. The microspheres were produced using a double emulsion solvent evaporation technique. All the microspheres preparation resulted in spherical shape and the mean diameter was 3 microm (for empty microspheres) and between 5 and 9 microm for microparticles loaded with GM. The encapsulation efficiency (EE) ranged from 3.4 to 90% depending on the formulation. Increasing the volume of the external aqueous phase, increased the EE. Encapsulation also depended on the pH value of the internal aqueous phase, the highest value was achieved when maintained the internal aqueous phase at pH 6, where GM was more soluble. Moreover, increasing nominal GM loading yielded lower encapsulation efficiencies. The release profiles of GM from microparticles resulted in biphasic patterns. After an initial burst, a continuous drug release was observed for up to 4 weeks. Finally, the formulations with higher loading released the drug faster.

A potential experimental model for the study of osteopenia in CCl4 liver cirrhotic rats.

In order to search for an experimental model to further investigate the osteopenia associated to liver cirrhosis (LC), this study has been focused on investigating the occurrence of bone disorders in male rats to which LC histologically confirmed was induced through the validated procedure of CCl4 inhalation. Length, anteroposterior and lateromedial diameters, densitometry, mechanical stress resistance, hydroxyproline (OHprol) and calcium and phosphate contents were measured in femurs from control (n = 10) and liver cirrhosis rats (n = 10). It has been found that femurs from liver cirrhosis rats showed a significant reduction (p < 0.01) in bone weight (0.254 +/- 0.003 vs 0.230 +/- 0.004 g/100 g b.w.), anteroposterior (4.08 +/- 0.06 vs 3.69 +/- 0.05 mm) and lateromedial (5.33 +/- 0.05 vs 5.08 +/- 0.04 mm, p < 0.05) diameters, resistance to mechanical stress (405.8 +/- 9.5 vs 332.5 +/- 9.1 N) and total densitometry (0.416 +/- 0.005 vs 0.381 +/- 0.004 g/cm2). However, no significant differences were observed in bone length, calcium, OHprol and phosphate (all expressed as mg/100 mg fresh bone tissue) contents. Therefore, the proteins matrix to mineral contents ratio was not altered. These results indicate that in this model of experimental liver cirrhosis there is osteopenia characterized by bone frailty and reduced thickness, and it could offer an experimental model to study bone changes associated to liver cirrhosis.