Abstract

Recently much emphasis is being laid on the development of microparticulate DDS in preference to single unit systems because of their potential benefits such as increased bioavailability, reduced risk of systemic toxicity, reduced risk of local irritation and predictable gastric emptying. The objective of the present study is to prepare and characterize starch acetate and to evaluate its application in the preparation of microparticulate drug delivery systems for oral controlled release of gliclazide. Starch acetate was prepared by acetylation of potato starch with acetic anhydride. The prepared starch acetate was characterized and evaluated. Starch acetate with a degree of substitution 2.75 could be prepared by acetylation of potato starch with acetic anhydride. The starch acetate prepared was feely soluble in chloroform and insoluble in several aqueous fluids and organic solvents. Chloroform could be used as solvent for starch acetate in the preparation of microparticles, microcapsules and in film coating Spherical starch acetate- Gliclazide microparticles could be prepared by the emulsification-solvent evaporation method. The method is industrially feasible as it involves emulsification and removal of the solvent, which can be controlled precisely. The emulsification solvent evaporation method was reproducible with regard to size and size distribution of the microparticles. About 65-70% of microparticles in each batch were in the size range 35/50 mesh (398.5µm) Encapsulation efficiency was in the range 96.0-99.3 % in the preparation of microparticles. Gliclazide release from the starch acetate microparticles was slow and spread over longer periods of time. The drug release d epended on the proportion of core:coat in the microparticles. A good linear relationship (R² = 0.826 ) between percent coat and release rate (k o) was observed. The relationship could be expressed by the linear equation, y = 12.18-0.173x where x is percent coat and y is release rate (ko). Gliclazide release from the starch acetate microparticles was by non fickian (anomalous) diffusion. Formulation F2 prepared using a Core :coat ratio of 8:2 gave slow, controlled and complete release(100%) of Gliclazide over 12 hours. As such formulation F2 is considered as a promising microparticulate DDS for oral control release of Gliclazide over 12 hours for b.i.d administration Key words: Multiparticulate drug delivery systems, Starch acetate, Gliclazide, Oral controlled release

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