MULTILAYERED HYDROPHILIC MATRICES AS CONSTANT RELEASE DEVICES (GEOMATRIX(TM) SYSTEMS)

In recent years many attempts have been made to modify drug release profiles from hydrophilic matrix tablets. Recently a new method based on the application of an inert impermeable coating on different sides of a matrix tablet was proposed. The coating delays the interaction of the matrix with the dissolution medium. In this way the hydration rate of the active core is slowed and its release surface is reduced. As a result the release extent is increased, while the dissolution profile tends to shift toward constant drug release compared with the uncoated matrix. In this article the design and technological development (up to the industrial production) of these types of devices is described: the film coatings are replaced by a polymeric barrier applied on the tablet bases during tableting. The effectiveness, the reproducibility and the technological characteristics of the new multi-layer systems are described.