FACTORS INFLUENCING THE RELEASE OF AMINOPHYLLINE FROM TABLETED ETHYLCELLULOSE MICROCAPSULES

Microcapsules containing aminophylline cores in ethylcellulose walls h ave been prepared and tableted. The mechanical properties and the rele ase characteristics of tablets obtained by direct compression at six d ifferent pressures (ranging from 265 to 1060 Kg.cm(-2)) were studied. The release rate of the drug from tableted microcapsules increased wit h the increase of compression force and was higher than from uncompres sed microcapsules, indicating that some damage of the polymeric wall o ccurred during the compression process. Among the various excipients t ested as binding and protective agents, paraffined starch (a mixed sys tem appositely set up) gave the best results, producing the slowest dr ug release rate. No important effect on drug release rate was found by changing the size of the microcapsules.