[Testing of drug release from film pellets with special consideration of the thickness of the polymer coating].

The influence of the thickness of polymer films on drug release was studied by means of an apparatus, developed especially for the examination of film-coated pellets. To show the direct dependence of the thickness of the polymer layer on the process of liberation a sequence of ten coating steps was chosen. On the contrary the release of active ingredients of varying dissolution behaviour was synchronous and didn't depend on the pH-value of the medium. The results show, that by using the proper coating material the thickness of the layer can be used to control the drug liberation process. The comparison of the release from different coating steps in the apparatus described makes it possible to produce mixtures of pellets with both a quick onset and a long duration of action by using only one type of coating material.