Critical Points in Biopolymeric-Controlled Release Matrix Systems

Abstract

Natural polymers have been extensively employed by the pharmaceutical industry due to their good safety profile, biocompatibility and biodegradability as well as the fact that they come from renewable sources. However, they show some disadvantages such as high solubility and low thermal stability which must be overcome in order to develop effective controlled release matrix systems. In this chapter, three different types of biopolymers have been considered: natural polymers, chemically modified natural polymers, and new polymers based on natural products. These new products have been studied as alternatives to traditional synthetic excipients. Different tools have been employed to characterize their rheological properties as well as their suitability to be employed as controlled release excipients. Critical points of matrix systems prepared with dextran and with new polymers derived from sugar-based monomers have been explained according to percolation theory. Some of the new polymers studied show outstanding properties as controlled release excipients and, some of them, also as excipients for colon-specific drug delivery devices.