Naturally and chemically sulfated polysaccharides in drug delivery systems

Abstract

Sulfated polysaccharides have always attracted muchattention in food, cosmetic and pharmaceutical industries. Thesepolysaccharides can be obtained from natural sources such as seaweeds (agarans,carrageenans, fucoidans, mannans and ulvans), or animal tissues(glucosaminoglycans). In the last few years, several neutral or cationicpolysaccharides have been sulfated by chemical methods and anionic oramphoteric derivatives were obtained, respectively, for drug delivery and otherbiomedical applications. An important characteristic of sulfatedpolysaccharides in this field is that they can associate with drugs generatingpolyelectrolyte-drug complexes, or with cationic polymers to forminterpolyelectrolyte complexes, with hydrogel properties that expand even moretheir applications. The aims of this chapter are to present the structuralcharacteristics of these polysaccharides, to describe the methods of sulfationapplied and to review extensively and discuss developments on their use bythemselves or taking part of interpolyelectrolyte complexes in drug deliveryplatforms. A variety of pharmaceutical dosage forms which were developed andadministered by multiple routes (oral, transdermal, ophthalmic, and pulmonary,among others) to treat diverse pathologies were considered. Different IPECs were formed employing these sulfated polysaccharides asthe anionic component. The most widely investigated is κ-carrageenan. Chitosanis usually employed as cationic polyelectrolyte contraion, with a variety ofsulfated polysaccharides, besides the applications of chemically sulfatedchitosan. Although chemical sulfation is often carried out in neutralpolysaccharides and, to a less extent, in cationic ones, examples ofoversulfation of naturally sulfated fucoidan have been found which improve itsdrug binding capacity and biological properties.