Oral sustained-release drug delivery systems using polycarbonate microspheres capable of floating on the gastric fluid.

Polycarbonate microspheres loaded with aspirin, griseofulvin and p-nitroaniline were prepared by a solvent evaporation technique. High drug loading (> 50%) was achieved by this process. Drug-loaded microspheres were found to float on simulated gastric fluid and intestinal fluid. Drug-release studies were carried out in these fluids at 37 degrees C. Increasing the drug to polymer ratio in the microspheres increased both their mean particle size and the release rate of the drugs. It was concluded that sustained delivery of drugs could be effected using this matrix.