30] Controlled release and magnetically modulated release systems for macromolecules

Abstract

This chapter presents the methodology of formulating of polymeric delivery systems. The methods of preparing polymeric delivery systems, methods of regulating the release kinetics of these systems, and a discussion of the advantages and limitations of the systems as well as potential directions for future research in this area are presented. The basis for the slow release of macromolecules through these polymers appears to be diffusion through a series of interconnecting macrochannels in the polymer matrix. These channels do not normally exist within the polymer but are caused by the incorporation of solid or liquid in the matrix during the casting procedure. Thus, factors that increase the size of these channels or provide simpler pathways (lower tortuosity) for diffusion out of the matrix would be expected to increase release rates. Modulated delivery systems controlled by external means may ultimately improve the release pattern of certain drugs such as insulin. Modulated release systems triggered by magnetism or other mean may also be useful for delivering hormones for birth control and other therapies.