In this research controlled release microspheres of Rivastigmine tartrate was prepared by solvent evaporation method using ethyl cellulose polymer and particle size, encapsulation efficacy, drug content, in vitro release of microspheres were evaluated. The results showed that the encapsulation efficiencies were desired for all the formulations. Particle sizes of the microspheres were influenced by concentration of ethyl cellulose and stirring speed. The invitro release of the F3 formulation recorded the optimum release with stirring at different RPM. The controlled release microspheres were successfully developed by solvent evaporation method using ethyl cellulose polymer. From this study it is concluded that the drug polymer ratio and stirring speed were important for obtaining the desired spherical particles. Rivastigmine tartrate microspheres could be prepared with various particle sizes and in vitro drug release pattern. The particle size of microspheres, drug content and polymer concentration could determine the rate and pattern of drug release. It can be seen that by increasing the polymer concentration, the rate of drug release from the microspheres decreases.
