The subject invention provides a drug delivery system comprising at least one compartment comprising (i) a drug-loaded thermoplastic polymer core layer, (ii) a drug-loaded thermoplastic polymer intermediate layer and (iii) a non-medicated thermoplastic polymer skin covering the intermediate layer, wherein said core layer is loaded with crystals of a first (pharmaceutically) active compound and said intermediate layer is loaded with, crystals of the second (pharmaceutically) active compound.