The present invention is directed to implantable medical devices which may be used for controllably releasing a therapeutic agent within a patient and methods for making the same. These medical devices may include porous coatings, which may be polymer-free, located on an outer surface or abluminal surface of the medical device. The medical device may be a stent. The pores of the porous coating may be expandable to facilitate loading of the therapeutic agent. The medical device may be triggerable upon implantation of the medical device such that the volume of the voids shrinks to eject the therapeutic agent. The voids may be slots in the stent. Expandable materials or structures may be positioned in the voids to expand upon implantation and eject the therapeutic agent.