Abstract: A delivery system including at least one core and a membrane. The core and the membrane include an elastomer composition containing, e.g., poly(dimethylsiloxane), a siloxane-based elastomer having 3,3,3-trifluoropropyl groups attached to the Si-atoms of the siloxane units and/or poly(alkylene oxide) groups, present as alkoxy-terminated grafts or blocks linked to the polysiloxane units by silicon-carbon bonds, or as a mixture of these forms. The delivery system is preferably an implant or an interuterine, intracervical or intravaginal system.