According to an aspect of the invention, medical devices are provided which include a substrate, at least one porous reservoir containing at least one therapeutic agent disposed over the substrate, at least one nanoporous layer disposed over the at least one porous reservoir, and at least one plugged aperture, which may be located within the substrate, within the nanoporous layer, or both. According to another aspect of the invention, a method of forming a medical device is provided which includes (a) forming a porous reservoir over a substrate, (b) forming a nanoporous layer over the porous reservoir, (c) forming an aperture within the substrate or the nanoporous layer, (d) filling the porous reservoir with therapeutic agent through the aperture, and (d) plugging the aperture.