Cellulose acetate microspheres prepared by o/w emulsification and solvent evaporation method

The study is concerned with the development of cellulose acetate microspher es by the o/w emulsification and solvent evaporation method in the presence of polyvinyl alcohol as an emulsifying agent. The influence of process par ameters such as solvent mixture (acetone + dichloromethane) composition, co ncentration of the emulsifying agent and speed of stirring has been examine d. The microspheres have been analysed for their size, drug loading capacit y and release kinetics. Spherical and smooth surfaced microspheres with enc apsulation efficiencies ranging between 73-98% were obtained. Use of aceton e in the oil phase drastically reduced the particle size. Slow drug release from microspheres occurred up to similar to 8 h and the release was found to be non-Fickian. An optimization procedure was employed to investigate an d identify the key parameters affecting the properties of the microspheres. A 3(3) randomized full factorial design was used in the analyses of the da ta. A linear model with interactive terms was generated using a multiple li near regression approach. The statistical analysis confirms the significant effect of solvent composition and concentration of emulsifying agent on th e drug release characteristics.