9564. Hence, the results revealed that all the formulations (F-1–F-4) release the drug by zero-order kinetics. Higuchi’s model was applied to the in-vitro release data, linearity was obtained with high ‘r’ value indicating that drug release from the controlled-release 5 FU beads through diffusion. The value of ‘n’ obtained for all the formulations ranged from 1.51 to 1.56 suggesting probable release by non-Fickian super case II. The swelling studies for beads were performed in a dissolution medium. The swelling studies that were carried out showed that maximum swelling for all batches

took place 12 h from exposure. The swelling of calcium alginate beads in the phosphate buffer was related to the Ca2+ and Na+ exchange. In the initial phase the Na+ ions present in the phosphate buffer exchanged with the Ca2+ ions bound to the COO− groups of the mannuronic blocks. As a result, an electrostatic repulsion between the negatively charged COO− groups increased, resulting in gel swelling. BIBW2992 mw The exchanged Ca2+ ions precipitated in the form of insoluble calcium phosphate, which was reflected in the slight turbidity

of the swelling medium. In the later phase of swelling, diffusion of Ca2+ from the polyguluronate blocks caused loosening of the tight egg-box structure, and thus permitted the penetration of additional amounts of media into the beads. The formulated beads on immersion in 0.1 N hydrochloric acid media they remain buoyant for 12 h with lag time of 97–234 s. KHCO3 was added as a gas-generating agent. The optimized concentration of effervescent mixture utilized aided in the buoyancy of all tablets. This may be due to the fact that effervescent mixture in tablets produced CO2 that was trapped in swollen matrix, thus decreasing the density of the tablet below 1 making the tablets buoyant. All the batches showed good floating

ability with the simulated gastric fluid, pH 1.2, for 12 h. The formulated beads of optimized Formulation-4 were sealed in vials and kept for 90 days at 40 °C/75% RH. The percentage drug content and drug release from Formulation-4 after 90 days of exposure were found to be 99.12 ± 0.80 and 95.17% respectively below (as shown in Table 5). In the present study floating zidovudine alginate beads were formulated by the ionotropic gelation method. The physical characterization, entrapment efficiency, drug content, and release profile were determined for the formulated zidovudine alginate beads. The formulated beads were found to release the drug at a predetermined and controlled. Thus, the present results confirmed that the formulated zidovudine alginate beads were found to be stable, and the floating ability of the formulated beads was found to be excellent. All authors have none to declare. Author’s are thankful to AstraZeneca Bangalore, Hyderabad for providing gift sample of zidovudine. The authors are also thankful to Mr. Joginpally Bhaskar Rao, chairman, and Dr. A.