Alginate-based target specific bioadhesive drug delivery systems: a review

In the field of drug delivery, bioadhesion refers to localization of dosage form to a specific region of the body. Bioadhesive drug delivery has gained the attention of pharmaceutical researchers for its ability to attach with the epithelial cell layers and control the release of the drugs till desired time duration. In case, the dosage form adheres with a mucosal layer, the phenomenon is known as mucoadhesion. Several natural polysaccharides exhibit bioadhesive behavior. Alginate is one such naturally obtained polysaccharide that possesses bioadhesive nature and is widely employed in effective localization of therapeutic agents. The safety profile of alginate, in combination with its biodegradable and biocompatible profile has made it an attractive biopolymer. The bioadhesive behavior, hydrogel forming ability, excellent mechanical property, easy extraction, and abundant availability in nature has favored the widespread use of alginate as a pharmaceutical excipient. This has also encouraged pharmaceutical scientists to employ alginate in developing several drug delivery systems for effective targeting to buccal, gastro-intestinal, skin, ocular, nasal and vaginal region. Despite its various advantages, there are numerous challenges which are also associated with it like variability in alginate based composition, limited mechanical strength under physiological conditions and potential for premature drug release are also discussed. Current research gaps includes the need for the development of standardized characterization methods with improved understanding of the interaction with alginate with the mucosal tissues. The future directions emphasizes the development of hybrid systems by development of alginate based formulations with combination with other polymers for optimizing the bioadhesion and therapeutic efficacy. This review will provide the insights about the potential and limitations of alginate as a bioadhesive excipient and will guide the future pharmaceutical applications in targeted drug delivery.