Preparation and Characterization of Chitosan Nanoparticles for Zidovudine Nasal Delivery.

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 the nanoparticles is very important for the mucoadhesive properties due interaction with the sialic groups of the mucin. Nuclear resonance magnetic data showed that the higher concentration of chitosan in the nanoparticles favored the interaction of few phosphate units (pyrophosphate) by ionic interaction Scanning electron microscopy, revealed that the nanoparticles are nearly spherical shape with porous surface. The entrapment efficiency of AZT, was 17.58% ± 1.48 and 11.02% ± 2.05 for NP1 and NP2, respectively. The measurement of the mucoadhesion force using mucin discs and nasal tissue obtained values of NP1 = 2.12 and NP2 = 4.62. In vitro permeation study showed that the nanoparticles promoted an increase in the flux of the drug through the nasal mucosa. In view of these results, chitosan nanoparticles were found to be a promising approach for the incorporation of hydrophilic drugs and these results suggest that the CS-containing nanoparticles have great potential for nasal AZT administration.

Rheological, mechanical and adhesive properties of surfactant-containing systems designed as a potential platform for topical drug delivery.

In the last few decades, nanotechnology has led to an advance in the development of topical drug delivery. Nanostructured drug delivery systems enable the compartmentalization of drugs in restricted environments, modifying the release profile and maintaining the required drug concentration for prolonged periods at the site of action and/or absorption. The development of nanostructured systems containing surfactants has evolved rapidly. Mixtures of surfactant, oil and water can self-associate to form structures, such as microemulsions and liquid crystal phases, which can be exploited as drug delivery systems because their nanostructured organization can control drug release. Therefore, the purpose of this study was to assess the potential of systems containing polyoxypropylene (5) polyoxyethylene (20) cetyl ether as surfactant, oleic acid or mineral oil as the oily phase, and water to be used as a platform in the development of topical drug delivery systems. Physicochemical characterization of the systems was performed by polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), rheological tests and texture profile analysis. The ternary phase diagrams showed that combinations of surfactant/mineral oil/water and surfactant/oleic acid/water could form various thermodynamically stable structures, such as microemulsions and liquid crystals. The oily phases, oleic acid and mineral oil, changed the rheological, mechanical and adhesive properties of systems containing polyoxypropylene (5) polyoxyethylene (20) cetyl ether.