Preparation of albumin microspheres by the emulsification technique

ABSTRACT

Egg albumin microspheres have been prepared by the emulsification procedure. The most important variables in the production of albumin microspheres have been studied. Increasing the albumin concentration gave rise to an increase in both the mean size and the size distribution of the prepared microsphere due to its effect on the viscosity of the dispersed phase. In order to obtain larger microspheres, relative low stirring speeds have been chosen. Heat was used to denature the albumin, rapid heating seemed to facilitate aggregation of the formed microspheres. In an attempt to control the particle size of the dispersed phase, different concentrations of sorbitan trioleate have been used during the preparation. The presence of excess concentration of drug on the surface of the microspheres resulted in a burst effect for drug release in 0.1 N HCl with up to 25% drug released in 5 minutes. Spermaceti and beeswaxes were included in an effort to slow drug release and to eliminate the initial burst effect. Drug release was found to vary with type and level of wax and the degree of thermal treatment. In vitro drug release profiles were evaluated for the untreated and treated spheres at room temperature and at 80C. In general, the simple incorporation of wax into the microspheres did not provide the desired controlled release of the drug. Thermal treatment of the albumin microspheres, however, resulted in a products which behaved in a different manner during dissolution testing and in general, provided slower release