Design and Evaluation of Alginate Based Mucoadhesive Microcapsules of Gliclazide by Orifice-Ionic Gelation Method

Abstract

The objective of the study is to design and evaluate alginate-based mucoadhesive microcapsules of gliclazide for controlled release. Microcapsules with a coat consisting of alginate and a mucoadhesive polymer such as sodium carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), carbopol, methyl cellulose could be prepared by orifice-ionic gelation method. The microcapsules are spherical, discrete, free flowing, multinucleate and monolithic type. The microcapsules are uniform in size with a mean size of 920 μm (18/20 mesh). Gliclazide content was uniform in a batch of microcapsules. Microencapsulation efficiency was in the range 98.5 - 101.5 %. Gliclazide release from the microcapsules was slow over 24 h and depended on core:coat ratio and composition of the coat i.e. the mucoadhesive polymer present in the coat. Release was diffusion controlled and followed first order kinetics. Non-Fickian diffusion was the drug release mechanism from the microcapsules. Microcapsules prepared with alginate alone as coat gave very slow release, less than 20 % in 24 h. Incorporation of a mucoadhesive polymer in the alginate coat has improved drug release and alginate based mucoadhesive microcapsules provided slow release of gliclazide over 24 h. The order of increasing release rate observed with various microcapsules was carbopol-alginate < methyl cellulose-alginate < sodium CMC-alginate < HPMC-alginate. Alginate based microcapsules prepared also exhibited good mucoadhesive property. Alginate-HPMC (1:1) microcapsules prepared at a core:coat ratio of 1:9 gave slow, controlled and complete release of gliclazide over 24 h and were found suitable for once a day administration.