Galactomannans: Old and new pharmaceutical materials

Abstract

Galactomannans (guar gum, locus bean gum or carob bean gum, tara gum) are natural plant polysaccharides traditionally used in Pharmaceutical Technology in the preparation of a great number of dosage forms. This kind of materials consists of chiefly high molecular weight hydrocolloidal polysaccharides composed of galactan and mannan units combined through glycosidic linkages. They are biodegradable, nontoxic, easily obtainable, and low cost products. They are available in a wide range of varieties with interesting rheological properties and biodegradation characteristics. Additionally, those properties can be physically, chemically or enzymatically modified to have tailor-made materials for new applications. In the last years an important work has been carried out within the pharmaceutical field directed to establish the utility of various natural polysaccharides such as galactomannans, as base excipients for the elaboration of specific drug delivery systems. Particularly challenging is the delivery of drug macromolecules like peptides or protein to the systemic circulation through colonic absorption, the development of transdermal therapeutic systems, the preparation of mucosa-adhesive drug delivery systems or the development of hydrogels for tissue repair. This chapter reviews the use of galactomannans as excipients in the pharmaceutical field. Particular emphasis was placed on the new applications of these old promising biodegradable polymeric materials.