FORMULATION AND CHARACTERIZATION OF GASTRORETENTIVE FLOATING MICROBALLOONS OF METFORMIN

Gastroretentive dosage forms have potential for use as controlled drug delivery systems. Multiple unit systems avoid the “all-or-none” gastric emptying nature of single unit system. A controlled release system designed to increase its residence time in the stomach without contact with the mucosa was achieved through the preparation of floating microballoons by the emulsion solvent diffusion technique using acrylic polymers (i.e. Eudragit RS-100 and Eudragit S-100) with drug (metformin) in a mixture of ethanol, dichloromethane and propanol. The effect of various formulation and variables on the internal and external particle morphology, micromeritics properties, in vitro floating behavior, physical state of the incorporated drug, drug loading and invitro drug release was studied. The microparticles were found to be regular in shape and highly porous. The release rate was determined in simulated gastro-intestinal fluids at 37^oC. The formulation demonstrated favorable invitro floating and release characteristics. The drug encapsulation efficiency was high. Incorporation of Eudragit RS-100 and Eudragit S-100 in the microballoons proved to be an effective method to achieve the desired release behavior and buoyancy. The designed system, combining excellent buoyant ability and suitable drug release pattern, could possibly be advantageous in terms of bioavailability of metformin