Current status of chitosan on dermal/transdermal drug delivery systems

In case of targeting the drug to the desired part of the skin, vehicles play animportant role, beside the characteristics of the drug. Many natural and synthetic vehicleshave been used for various topical dermal/transdermal preparations. However, chitosanhas been standing out with its many advantages based mainly on its biological andphysicochemical properties. Chitosan is a unique hydrophilic biopolymer obtained bypartial deacetylation of chitin, which is one of the most abundant polysaccharide. It is anatural product widely found in crustacean shells, fungal cell walls, insect exosceletons,and mollusks. Chitosan is a linear glycosaminoglycan made up of N-acetyl-Dglucosamineunits.Characteristics of chitosan, such as the molecular weight, viscosity and the degree ofdeacetylation, greatly influence the properties of formulations. The by-products formedafter the biodegradation of the polymer does not cause immune responses making itbiocompatible. Due to the specific cationic glucosamine groups of chitosan, it can beinteracted with anionic proteins in the skin providing the bioadhesive characteristics.These properties result in improved efficacy, enhanced bioavailability and reducedtoxicity-generally recognized as safe (GRAS). Furthermore, the antimicrobial/antibacterial and skin hydrating effects of chitosan have been received considerableattention for dermal/transdermal applications. It plays an important role in the cell regulation, tissue regeneration and collagen production. Chitosan and some of itscomplexes were approved by FDA for use in wound dressing products.Chitosan also provides the controlled release of numerous active agents used for thetreatment of skin diseases such as corticosteroids, antifungal agents, nonsteroidal antiinflammatorydrugs, hormones, local anesthetics, antiviral and antiseptic agents, etc.Regarding to the good bioadhesive property of chitosan and its ability to sustain therelease of the active compounds, it has found many practices in the formulation of gels,dermal/transdermal patches, sponges, micro-and nanoparticulate systems as drugcarriers. Particularly, chitosan has been used in the preparation of mucoadhesiveformulations, for improving the dissolution rate of the poorly soluble drugs, drugtargeting and enhancement of peptide absorption.This paper is focused on the use of chitosan for dermal/ transdermal drug deliverysystems following a general overview of chitosan. This natural polymer is a promisingcarrier or excipient as a delivery system and remarkable advances have been made aboutits potential applications in skin delivery. © 2011 by Nova Science Publishers, Inc. All rights reserved