A safe and efficient drug carrier must offer protection to human tissues in which it is administered as well as protection to the drugs against degradation, improve therapeutic effect, prolong biological activity, control drug release rate, and decrease the frequency of administration. These characteristics could be achieved by using chitosan to prepare carriers of drugs. It is almost the only cationic polysaccharide in nature with a great innate medical potential. Chitosan, a cationic polymer of natural origin, is a remarkable example of an excipient which currently has enormous potential for using in pharmaceutical dosage forms because of its properties as polyelectrolyte with reactive functional groups, gel-forming capability, high adsorption capacity, biodegradability and biocompatible and non-toxic to living tissues as well as having antibacterial, antifungal and antitumor activity. These functional properties provide suitability and extensive pharmaceutical applications such as for the preparation of drug delivery systems (drug conjugate, micro/nanoparticles, hydrogels, emulsions, biodegradable release system, etc.) and for regenerative medicine for many components such as proteins/peptides, growth factors, anti-inflammatory drugs, antibiotics intended to be administered in non parenteral routes (oral, topical, intranasal, vaginal, rectal and ocular). Interesting applications of chitosan has been receiving considerable attention since it has been developed systems more versatile by the incorporation of chitosan and other components in novel systems. They have provided a strategy for the functionalization by modulating physicochemical properties (hydrophilicity, surface charge, etc.) improving the encapsulation, stability, and protection of drugs. The recent development of nanotechnology and the various processes of funcionalization of chitosan have increased and improved its functionality as drug carrier.
This work reviews the drug carrier systems using chitosan to improve and increase the delivery of drugs for non parenteral routes. The most important properties of chitosan, the types of systems intended to be used for non parenteral routes, the strategies for the functionalization of chitosan systems by the incorporation of other components, advantages and limitations, and the relevance of pharmaceutical, pharmacological and toxicological experimental studies are reviewed in different drug carrier systems from chitosan.