Abstract: 
In this study, the floating microballoons of indomethacin were prepared by o/o solvent evaporation technique using Eudragit RS 100 as a wall polymer. Amongst different wall polymers, therapeutic agents and the anti-tacking agents, only, Eudragit RS 100: indomethacin: magnesium stearate system was able to float for a prolonged period of time. Thus, microballoons with this system were produced and evaluated for the impact of core: coat ratio, viscosity of liquid paraffin and stirring speed of external phase (EP). Increase in polymer concentration increased the particle size, drug loading, buoyancy, and decreased the porosity and drug release rate of microballoons. In contrast, increase in stirring speed and viscosity of EP decreased the particle size, buoyancy, drug loading, and increased the porosity and drug release rates of microballons. Microballoons particle sized ranged from 164 to 247 µm. Microballoons prepared with polymer: drug ratio of 2:1 released 28.31% drug at the end of 10 h. Drug release from most of the formulations followed Hixson-Crowell kinetic equation. Results revealed that Eudragit RS 100 can form floating microballoons with indomethacin conceivably by the formation of network between the quaternary ammonium groups of Eudragit RS 100 and Cl of indomethacin. Such microballoons, owing to their floating propensity, are promising candidates for sustained drug release.

Keywords: Eudragit RS 100, Indomethacin, Floating Microballoons, Solvent Evaporation, Magnesium Stearate, Hixon-Crowell Kinetics.