The disclosure relates to a drug delivery system comprising at least one core comprising one or more therapeutically active substances and at least one membrane encasing the core, characterized in that the system further comprises an intermediary layer of a substantially inert material that is not covalently bound to the material of the core or the membrane and wherein the substantially inert material is selected from the group consisting of silica, fumed and precipitated silicas and talc. The system may be a vaginal delivery system, an implant, an intrauterine delivery system, an intracervical delivery system, a helical coil or a spring.
