Abstract
Purpose:
The Chitosan, a polycationic biopolymer with mucoadhesive properties, presents a promising future in the prolonged ocular delivery of drugs. It also presents biodegradability, biocompatibility, nontoxicity and ability to increase paracellular transport of drugs. These properties allow their use as vehicles for ophthalmic formulations.The aim of this study was to develop and characterize NLC coated with chitosan (NLC-C) containing dexamethasone acetate.
Methods:
The NLC was formulated using 6.0% (w/w) cetyl palmitate (CP), 4.0% (w/w) capric/caprylic triglycerides (CCP),1.5% (w/w) tween® 80, 2.5% (w/w) lutrol®, 0.25% (w/w) soy lecithin (SL), 0.5% (w/w) sodium dodecyl sulphate (SDS) and 0.05% (w/w) dexamethasone acetate and obtained by high pressure homogenization (HPH). The dexamethasone acetate was incorporated in the lipid phase.CS- NLC was obtained by dissolving 5.0 mL of chitosan dispersion (CS) 0.75% w/v, in 5.0 mL of the nanoparticle suspension under magnetic stirring of 200 rpm for two hours. Measures of mean diameter, polydispersity index (PI) and zeta potential (ZP) were performed on Zetasizer Nano ZS90®. The NLC and CS-NLC were maintained at temperature of 6oC ± 2,0 and were performed in order to evaluate their stability.
Results:
The nanoparticles presented mean diameter of 170.5 ± 2.19 nm, PI equal to 0.141 ± 0.01 and ZP of -40.9 ± 0.42 mV. After the coating procedure, the mean diameter, the PI and the ZP were changed to respectively 642.7± 6.08 nm, 0.269 ± 0.02 and +50.4 ± 0.63mV. As expected, the NLC-C presented larger mean diameter and an inversion of the surface charge, which indicated the coating efficiency. The CS- NLC did not show any increase during a 30-day period. It seems that the coating was important to CS-NLC stability.
Conclusions:
The values obtained for zeta potential after the coating procedure supports the conclusion that chitosan was adsorbed on the nanoparticle surface. The coating also contributed to the maintenance of CS-NLC stability. The developed system in this study showed interesting properties and therefore it can be proposed as promising drug delivery system to improve the therapeutic efficacy of ophthalmic preparations containing dexamethasone acetate.
Keywords: 607 nanotechnology •
467 clinical laboratory testing •
541 glycoconjugates/glycoproteins