A medical device coated with carrier macromolecules, wherein the carrier macromolecules are conjugated with a therapeutic agent. The carrier macromolecules may be antibodies which bind the therapeutic agent at the antigen binding site or by covalent bonding. The carrier macromolecules may be tethered to the surface of or dispersed within a coating on the medical device. The carrier macromolecules may release the therapeutic agent upon exposure to a trigger, which may be exposure to an aqueous environment, or a change in the pH or the ionic strength of the environment. The carrier macromolecules may also be bispecific antibodies directed to both a therapeutic agent and a target antigen. In some cases, binding of the target antigen causes the therapeutic agent to be released from the bispecific antibody. Also provided are methods of controlling the release and targeting of therapeutic agents eluted from a medical device.