Factors affecting preparations of chitosan microcapsules for colonic drug delivery

Abstract

This work aimed at studying factors affecting preparations of chitosan microcapsules for colonic drug delivery. Chitosan microcores (CS, 45kDa, 87% degree of deacetylation) containing diclofenac sodium (DS) coated with Eudragit®S100 (ED) were prepared by a desolvation technique. Sodium sulfate was used as a desolvating agent and the drying process was freeze-drying. Factors affecting morphology, particle size and zeta potential of microcapsules were evaluated, i.e. weight ratio of DS:CS:ED, surfactant (polysorbate 80), anti-adherent (silicon dioxide), and the use of sonication or homogenization in preparation processes. The weight ratio of DS:CS:ED at 1:2:6 provided the smallest microcapsules of about 82.37±1.61 micrometer in diameter and they were in aggregated forms. Zeta potential of the microcapsules was around -25.74 +4.78 mV which indicated that the core particles of CS and DS with zeta potential of 42.14±1.74 mV were encapsulated by ED. Increasing the amount of CS and ED, the size of microcapsules was increased but the zeta potential was not affected. Adding of polysorbate 80 could not reduce the size of microcapsules, but silicon dioxide could reduce the size and aggregation of microcapsules. Finally, the use of sonication and homogenization were effective in reducing of the size of microcapsules to 53.45 +0.63 and 58.72+1.28 micrometers, respectively.