INFLUENCE OF GLUTARALDEHYDE ON DRUG-RELEASE AND MUCOADHESIVE PROPERTIES OF CHITOSAN MICROSPHERES

Among bioadhesive drug delivery systems, chitosan microspheres can be considered useful formulations for mucosal administration of drugs. Th e feasibility of modulating drug release from chitosan microparticles is due to polymer cross-linking, i.e, by glutaraldehyde, The aim of th is work was to develop a new simple 'in vitro' technique based on elec tron microscopy in order to study the effect of polymer crosslinking d ensity on mucoadhesive properties of the chitosan microspheres. This t echnique consists of scanning electron microscopy (SEM) and transmissi on electron microscopy (TEM) observations on morphological changes of chitosan microspheres with various cross-linking densities in contact with mucin solution. The results of SEM and TEM analyses have permitte d to confirm the high affinity for mucin of uncross-linked chitosan mi crospheres and thus their bioadhesive properties. Moreover, bioadhesiv e characteristics of the microparticulate drug delivery systems were d epressed for glutaraldehyde cross-linked chitosan microspheres. (C) 19 98 Elsevier Science Ltd. All rights reserved.