Water soluble drug delivery systems based on a non-biological 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 weight fractions have been blended in order to tune the release mechanism. Drug release kinetics have been closely related to swelling and dissolution properties of the adopted matrices. In particular the development of the external swollen layer of the tablet as well as the kinetic of dissolution have been monitored. The different drug delivery behaviours observed were related to the different matrix properties. Viscoelastic 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, also the viscoelastic properties of the water-polymer gel must also be taken into account. A good interpenetration between the adjacent layers of the mucus and the polymer gel is ineffective in holding the mucoadhesive tablet at a specific site if the polymer gel does not have a proper viscoelastic behaviour. The best compromise between good release, viscoelatic and mucoadhesive properties was obtained in the case of 50\% by weight blend of the two adopted polymer fractions (600,000 and 4,000,000 molecular weight).