FORMULATION AND EVALUATION OF COLON TARGETED MICROSPHERES OF GLIPIZIDE

The objective of the present study was to formulate and evaluate microspheres of Glipizide using guar gum and HPMC K4M as polymers for colon-specific delivery for better treatment of Type 2 diabetes. The glipizide microspheres were prepared by ionotropic gelation method by the use of various cross-linking agents. The microspheres were then studied for physical appearance, particle size, surface morphology, drug-polymer compatibility, and drug entrapment efficiency. The in-vitro drug release profile was studied in three different buffer medium using USP type I apparatus. Further, kinetic modeling was employed to find out the release mechanism. Glipizide microspheres showed high entrapment efficiency (89.80%) and the microspheres were free-flowing, non aggregated, and almost spherical between 500-700 μm in diameter. The FTIR spectrum showed that there is no interaction between the polymers and drug. The in-vitro release study found to be affected by using various cross-linking agents. The microspheres with barium chloride as cross-linking agents showing a small amount of drug release in acidic pH but show maximum drug release at the end of 12 h. It was found that the % cumulative release in microspheres encapsulated with guar gum was maximum for F2 (64.29%) and minimum for F6 (42.85%). The rate of drug release follows the Korsmeyer-Peppas model and zero-order kinetics. The colon targeted microsphere of Glipizide showed no change either in physical appearance, drug entrapment efficiency and dissolution pattern after performing stability study for 6 months.  The study reveals that glipizide loaded microspheres can be used effectively for colon targeting.