FREMGANGSMAADE TIL FREMSTILLING AF ET FARMACEUTISK PERORALT POLYDEPOTPRAEPARAT MED KONTROLLERET AFGIVELSE

A pharmaceutical oral multiple-units composition with controlled release, in which the individual units are coated units of an active substance, e.g. potassium chloride, which is subject to controlled release in consequence of the units being coated with a substantially water-insoluble, but with a water-diffusable coating, is prepared by applying on units comprising the active substance, a film-forming coating mixture comprising a solvent, a film-forming substance dissolved in the solvent and a hydrophobic substance, such as a wax, e.g. a paraffin wax, the film coating mixture being applied at a temperature higher than the melting point of the hydrophobic substance. The application is preferably performed in a fluidized bed. By thus incorporating a hydrophobic substance in the coating mixture in an amount of the order 1-25% in such a way that prior to the application, the hydrophobic substance is melted, but undissolved and microdispersed in the coating mixture, a coating is obtained which delays and controls the diffusion through the coating so that even easily soluble active substances, such as potassium chloride, can be slowly released.