A pharmaceutical composition for slow release of active ingredient in the gastrointestinal tract, comprising a plurality of active ingredient-containing particles coated with a material insoluble in gastric and intestinal juices, where the particles have as core a homogeneous mixture comprising an active pharmaceutical ingredient and a polymer insoluble in gastric and intestinal juices, with an average internal pore diameter not exceeding 35 m, makes efficient and pH-independent delaying of release possible even with comparatively small amounts of polymer. It is additionally distinguished by a long shelf life and is particularly suitable also for nonspherical particles.