Formulation and Evaluation of Metformin Hydrochloride Microspheres by Solvent Evaporation Method

The aim of the present study was to formulate and evaluate Metformin HCl microspheres to produce a drug delivery system with better pharmaceutical and therapeutic properties. Metformin HCl microspheres were prepared by using ethyl cellulose as a release retardant polymer by solvent evaporation method .Formulations F1, F2 and F3 were prepared using ethyl cellulose in the drug polymer ratio of 1:1, 1:2 and 1:3. A plasticizer (N-dibutyl phthalate) was added in formulations F4,F5 and F6 .The prepared microspheres were evaluated for the parameters like Percentage yield, Particle size analysis, Micromeritic properties like angle of repose, bulk density, tapped density, compressibility index, Hausner’s ratio, melting point determination, drug content estimation, microencapsulation efficiency and in vitro drug release studies. The in vitro release of Metformin HCl was slow and extended over longer period of time. As the concentration of polymer was increased, the drug release was decreased. The drug release was found to be slow in formulations F4, F5 and F6 when compared to F1, F2 and F3. Thus the study clearly indicated a promising potential of sustained release Metformin HCl microspheres containing ethyl cellulose as rate controlling polymer for effectively treating diabetes mellitus.