Preparation and Evaluation of Chitosan Microsphere of Metformin Hydrochloride and to Study the Effect of Drug to Polymer Ratio

Metformin hydrochloride is biguanide used as oral hypoglycemic agent. But its shows short biological half life (t1/2 3-4) which leads to high dosage frequency. Therefore, the present study aims to prepare the controlled release formulation of metformin hydrochloride loaded in the chitosan microspheres. It also involves the study of the effect drug to polymer ratio on the performance of chitosan microspheres. Chitosan microspheres were prepared by Solvent Extrusion Method using citric acid as a crosslinking agent. Two formulations with different drug polymer ratios (M1 high drug-polymer ratio and M2 low drug to polymer ratio) were prepared for their effect on performance. Formulated microspheres were characterized for its drug content, compressibility index, swelling index, surface morphology and particle size (SEM) and invitro drug release study. The characterization of fabricated microsphere showed smooth cracked to smooth porous surface with narrow particle range (600-800μm) and high drug content (75.83 and 73 % for M1 and M2, respectively). Compressibility index was founded between 10.6 and 5.53 % for M1 and M2, respectively. Both the formulations showed good percent swelling index. SEM showed nonporous, smooth and cracky surface for both the formulations. The microspheres prepared with high drug to polymer ratio showed higher in vitro drug release at the end of 12 h of the study. It was concluded that the chitosan microspheres could be considered for controlled drug delivery of metformin hydrochloride. The microspheres prepared with high drug to polymer ratio showed good drug content, compressibility index, swelling index, surface morphology and greater invitro drug release.