Preparation and Characterization of Chitosan Microparticles for Oral Sustained Delivery of Gliclazide: In Vitro/In Vivo Evaluation

Chitosan microparticles were prepared with tripolyphosphate (TPP) by ionic cross-linking with gliclazide (GLZ) as a model drug. The particle sizes of TPP-chitosan microparticles ranged from 675-887 mu m with loading efficiencies of greater than 94%. Chitosan concentration, TPP solution pH, and glutaraldehyde volume solution added to the TPP cross-linking solution affected drug release characteristics. Pectin interactions with cationic chitosan on the surface of TPP/chitosan microparticles led to the formation of polyelectrolyte complex films that improved drug sustained release performance. In vivo testing of the GLZ-chitosan microparticles in diabetic albino rabbits demonstrated a significant antidiabetic effect of GLZ/chitosan microparticles after 8 h that lasts for 18 h compared with GLZ powder that produced a maximal hypoglycemic effect at 4 h, suggesting that GLZ/chitosan microparticles represent an improved system for the long-term delivery of GLZ. Drug Dev Res 72:235-246, 2011. (C) 2010 Wiley-Liss, Inc.