Retard implantation tablets on a matrix base with Eudragit as a structural substance.

A model for prolonged availability of low concentrated drugs was successfully tested by using 7-hydroxyethyltheophylline and Eudragit RS 100 as matrix to form implant-tablets. Those tablets have the same size, same weight, same hardness, but a different concentration of the model substance and are coated with liquid Eudragit RS 100. Statistical evaluation of the different liberation rates led to a drawing of a diagram whereby a desired drug liberation up to 6 d can easily be obtained by choosing a certain drug concentration of the tablet.