Processing factors affecting particle size and in vitro drug release of sustained-release ibuprofen microspheres

Abstract

Ibuprofen microspheres were prepared using an aqueous dispersion method. The method was adapted so that two processing factors, cooling time and stirring rate, could be altered. The subsequent effects of altering these parameters on the characterisation of the microspheres and the drug release kinetics were investigated. Particle size analysis showed that both stirring rate and cooling time significantly affected the mean particle size although the effects were independent of each other. In vitro release data were fitted to several models, the Higuchi square root of time model (with appropriate limits) giving the best fit for the release data. Increasing the cooling time or decreasing the stirring rate decreased the release of drug from the system. By using this method of manufacture, which allows alteration of processing parameters, it would be relatively straightforward to produce microspheres with tailored in vitro release characteristics.