Sodium alginate (SA) floating beads containing cefpodoxime proxetil, a third-generation cephalosporin antibiotic, were prepared by precipitation method using calcium carbonate as gas generating agent. Hydroxypropyl methylcellulose (HPMC) was used in all the four formulations in different proportions (F1, F2, F3, and F4) as swelling agent to control the release of the drug. Gas generating agent forms pores on the surface of the beads because of the rapid escape of CO2 during the curing process in precipitating media. Scanning electron microscopy confirmed their porous and grossly spherical structure, and the size of the beads were in the range of 700-1000 mu m. The size of the beads increases with the increase in the concentration of gas-forming agent and decreases with the increase in the concentration SA. The drug entrapment efficiency was found to be in the range of 85.3-91.1%,. F2 shows least entrapment, whereas F3 shows maximum entrapment. The percentage porosity was 82.1-89.7.%, and the mean pore diameter was 0.41-0.52 mu m. The porosity depends on the concentration of gas-forming agent. The mechanical strength of the beads was 591-1073 g. All the formulations showed good floating time. The in vitro release was performed in glycine dissolution media according to USP for about 12 h. The cumulative % drug release was found to be 67.5-87.3%. The in vitro dissolution study reveals that the concentration of the gas generating agent and SA affects the release rate. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1921-1926, 2009