Chitosan and its derivatives in mucosal drug and vaccine delivery

Numerous studies have demonstrated that chitosan and their derivatives (N-trimethyl chitosan, mono-N-carboxymethyl chitosan) are effective and safe absorption enhancers to improve mucosal (nasal, peroral) delivery of hydrophylic macromolecules such as peptide and protein drugs and heparins. This absorption enhancing effect of chitosans is caused by opening of the intercellular tight junctions, thereby favouring the paracellular transport of macromolecular drugs. Chitosan nano- and microparticles are also suitable for controlled drug release. Association of vaccines to some of these particulate systems has shown to enhance the antigen uptake by mucosal lymphoid tissues, thereby inducing strong systemtic and mucosal immune responses against the antigens. The aspecific adjuvant activity of chitosans seems to be dependent on the degree of deacetylation and the type of formulation. From the studies reviewed it is concluded that chitosan and chitosan derivatives are promising polymeric excipients for mucosal drug and vaccine delivery.