Potential applications of chitosan in oral mucosal delivery

The accessibility of the oral cavity makes application of drugs easy and acceptable to the patient, while permitting easy removal in the event of adverse reactions. Drugs penetrating the oral mucosa can be delivered systemically via direct entry into the systemic circulation thus avoiding the hepatic first-pass effect and degradation in the gastrointestinal tract. Due to the low permeability of the oral mucosa, new strategies are needed to improve the delivery of drugs across the mucosa. In order to improve the availability of drugs across the oral mucosa, mucoadhesive systems are applied to prolong the retention time of the delivery system on the mucosa. Furthermore, availability can be improved by using permeation enhancers. Chitosan with its favorable properties such as bioadhesivity, biodegradability, biocompatibility and permeation enhancing activity, offers great advantages over other polymers that are used for oral mucosal delivery. A wide choice of chitosan delivery systems such as solutions, gels, sponges, films, fibers, tablets and micro-/nanoparticles have been shown to be capable of delivering drugs into the oral cavity as well as across the oral mucosa. In this review, applications of chitosan for oral mucosal delivery will be reviewed and the possibilities and limitations discussed.