Abstract:
Floating alginate based microsphere system of Metformin Hcl was prepared by ionotropic gelation technique, with sodium bicarbonate as gas forming agent, swellable polymers Hydroxy propyl Methylcellulose (HPMC E50), Ethyl cellulose (EC) and calcium chloride gelling agent. Alginate microspheres were formed as alginate undergoes ionotropic gelation by calcium ions and carbon dioxide develops from the reaction of bicarbonate salt with acid which permeated through alginate matrix leaving gas bubbles or pores within, providing the buoyancy. The concentration of polymer used was optimized by using 3² factorial designs. A 3² factorial design was used to elucidate the effect of variables, concentration of polymers HPMC (X₁) and EC (X₂) as the independent variables. The prepared microspheres were evaluated for size analysis, drug loading, drug entrapment efficiency, buoyancy study, SEM and in vitro drug release. The size of alginate microspheres was found to increase with increase in concentration of polymers. Drug loading and drug entrapment efficiency and was found to be in acceptable range. All formulations possessed good floating properties with total floating time more than 12 hrs. From the study, it was concluded that spherical and free flowing microspheres of Metformin Hcl could be successfully prepared by ionotropic gelation technique with high entrapment efficiency and prolonged release characteristics.

Keywords: Metformin Hydrochloride, Gastroretentive Drug Delivery System, Ionotropic Gelation, Floating Microspheres, Controlled Release.