WATER-SOLUBLE DRUG-DELIVERY SYSTEMS BASED ON A NONBIOLOGICAL BIOADHESIVE POLYMERIC SYSTEM

Matrix properties and release behaviour of monolithic devices based on a water soluble polymer has been investigated. Polyethyleneoxides of different molecular weights have been used and different molecular wei ght fractions have been blended in order to tune the release mechanism . Drug release kinetics have been closely related to swelling and diss olution properties of the adopted matrices. In particular the developm ent of the external swollen layer of the tablet as well as the kinetic of dissolution have been monitored. The different drug delivery behav iours observed were related to the different matrix properties. Viscoe lastic properties of the matrices have been also investigated. In fact , in order to obtain effective bioadhesive drug release devices, apart from the intrinsic mucoadhesive capabilities of the used polymers, al so the viscoelastic properties of the water-polymer gel must also be t aken into account. A good interpenetration between the adjacent layers of the mucus and the polymer gel is ineffective in holding the mucoad hesive tablet at a specific site if the polymer gel does not have a pr oper viscoelastic behaviour. The best compromise between good release, viscoelatic and mucoadhesive properties was obtained in the case of 5 0% by weight blend of the two adopted polymer fractions (600,000 and 4 ,000,000 molecular weight).