The aim of the present study was to develop a delivery system wherein the retention of ofloxacin could be achieved for increased local action in gastric region against Helicobacter pylori infection. The formulation was optimized on the basis of in vitro buoyancy and in vitro release in citrate phosphate buffer (pH 3). The hydrodynamically balanced capsules were prepared by physical mixing of various grades of HPMC and poly(ethylene oxide) (PEO) alone as well as in combinations. Cellulose acetate pthalate, liquid paraffin, and ethyl cellulose were used as release modifiers so as to maintain release of drug over a period of 12 h. The capsules prepared with PEOWSR 60K and drug coated with 2.5% ethyl cellulose gave the best in vitro percentage release and were taken as the optimized formulations. Various grades of Eudragit and PEO were used in combination for formulating floating microspheres using solvent diffusion technique for preparation of multiple unit system. The use of two different solvents (dichloromethane and ethanol) that differed in the rate of diffusion led to formation of a hollow core in the microspheres, which was partially responsible for the flotation ability. The in vitro release of the floating capsules and microspheres was found to be 96.02% and 95.83% in 12 h, respectively. Both the dosage forms follow Higuchi model for release from formulations. By fitting the in vitro release data of single unit dosage form into zero-order, first-order, and Higuchi model, it could be concluded that the release followed Higuchi model, as the correlation coefficient (R2 value) was higher than those in the other two release models. In both cases of single and multiple unit dosage form, R2 values for Higuchi model were found to be good, showing that drug release followed non-Fickian diffusion mechanism.
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