Preparation and Evaluation of Chitosan Microcapsules of Metronidazole using Tripolyphosphate Cross-linking Method

Abstract

Metronidazole microcapsules with a coat consisting of alginate and the natural cationic polymer,
chitosan were formulated by using tripolyphosphate cross-linking method and were investigated with a view to
develop mucoadhesive microcapsules. The microcapsules were evaluated for their surface morphology,
microencapsulation efficiency, in-vitro wash-off test, swelling behavior and in-vitro drug release. The microcapsules
formed had rough surface morphology in scanning electron microscopy. The drug entrapment efficiency was found to
be in the range 75.2±1.31% and 82.1±0.75%. Chitosan microcapsules displayed a limited amount of swelling which
is supposed to be related to the degree of cross-linking with tripolyphosphate. The microcapsules showed better
mucoadhesive property at intestinal pH 7.4 than at gastric pH 1.2 in the in-vitro wash-off test. The drug release was
found to be slow and extended over long duration of time.