Gastroretentive microballoons of riboflavin: formulation and evaluation

Gastroretentive dosage forms are useful to extend release of drugs having a narrow window of absorption in the upper intestine and for drugs degraded by higher pH or for drugs with local action in the proximal part of the GI tract. In the present study, an attempt was made to prepare microballoons of riboflavin by emulsion solvent diffusion method by using HPMC and ethylcellulose in order to extend the drug release in the upper GIT, which may result in enhanced absorption and thereby improved bioavailability. The size and surface morphology of riboflavin microballoons were characterized by optical and scanning electron microscopy. FTIR and DSC studies revealed no drug excipient interaction. Average particle size of microballoons was found to be between 126.8±2.26 to 163.4±2.52 μm. Microballoons were found to be spherical in shape with smooth surface texture. Percentage yield of the microballoons was satisfactory. In vitro buoyancy of the optimized riboflavin microballoons was found to be 96.24±0.08%, indicating good floating in stomach. Cumulative amount of drug release from microballoons at the end of 12 hr was 99.78±2.78 % and followed Highuchi diffusion kinetics and super case II transport.