ABSTRACT
In recent years, the delivery of drugs using natural polysaccharides has attracted considerable attention of the pharmaceutical scientists especially due to their inert, biocompatible and biodegradable nature. Moreover, the presence of a variety of functional groups in biopolymer structure allows a number of chemical conjugation reactions. Chemical conjugation of drugs to native or modified biopolymers may lead to the formation of stable bonds such as ester, amide, and disulfide that can retard drug release 126during its transport before the cellular localization of the drug. In addition, polymer-drug conjugates offer a number of advantages over their small therapeutic precursors. Polymer-drug conjugates can enhance water solubility and bioavailability of drug, provide protection to the drug from deactivation and preserve drug activity during circulation, transport to targeted organ or tissue and intracellular trafficking. The conjugates can also be used to alter pharmacokinetics and biodistribution of drugs, which exhibit short blood plasma half-lives. Furthermore, the conjugation approach provides an opportunity for passive or active targeting of drugs specifically to the site of action. Therefore, the polymeric prodrug conjugates are being widely investigated to solve different bio-performance related issues for a variety of drugs. This overview focuses on some water-soluble natural polymers such as alginate, pullulan, dextran and pectin; and their drug conjugates. The achievements in the field of biopolymer-drug conjugates are discussed herein.
