The invention relates to novel particulate drug-delivery systems based on a polymer support containing at least one linear, branched or cross-linked polymer in a fraction of over 50 percent by weight in relation to the total weight of the support. The system is characterised in that at least one signal substance for transport through a biological barrier and at least one active ingredient are stored, the support, signal substance and active ingredient having no covalent links and no active-ingredient specific and signal substance specific coordinative links between one another.