Abstract: An improved implantable pharmaceutical depot for the prolonged release of at least one biologically active substance, the depot comprising a polymeric carrier and the biologically active substance, the improvement wherein the depot is coated or surface modified with a biologically active and biocompatible glass, glass-ceramic or ceramic material, the coating or modified surface being capable of forming a bond to soft tissue upon implantation. Methods for forming the biologically active and biocompatible glass, glass-ceramic or ceramic coating or modified surface on the silicone based depot are also disclosed.