Natural Polysaccharide Hydrogels as Novel Excipients for Modified Drug Delivery Systems; a Review

Drugs are rarely administered as pure chemical substances alone and are almost always given as formulated preparations or medicines. Drug dosage forms contain many components in addition to the active pharmaceutical ingredient(s) to assist in the manufacturing process as well as to optimize drug delivery. Due to advances in drug delivery technology, excipients are currently included in novel dosage forms to fulfill specific functions and in some cases they directly or indirectly influence the extent and/or rate of drug release. Developments of several drug delivery systems are based on natural polysaccharides act as excipients that do not change their chemical structure but these materials degrade within the body as a result of natural biological processes, eliminating the need to remove a drug delivery system after release of the active agent has been completed. Furthermore, polysaccharides are chemically well-defined and have attracted worldwide attention as excipients due to their novel and unique physico-chemical properties can be relatively low cost and can be chemically modified to suit specific needs. Some natural polysaccharides have even shown environmental-responsive gelation characteristics with the potential to control drug release according to specific therapeutic needs. This review discusses some of the most important natural polymeric compounds that are used or investigated as excipients in drug delivery systems.