An implantable composite device for regulated delivery of bioactive agents to the site of implantation includes at least two zones of distinct porosities through its cross-section. One zone is of a sufficient porosity to permit regulated transport of bioactive agents associated with the device to an area of the body in need of treatment. The bioactive agent associated with the device an be either a therapeutic or diagnostic agent. In a particular embodiment of the invention, the device includes a tubular body consisting of a first luminal layer of ePTFE a porosity sufficient to promote cell endothelization along the luminal surface and a second polymeric layer disposed on the first layer of a porosity permitting regulated transport of the bioactive agents.
