A medical device includes an implantable structure and a coating layer including a water-insoluble therapeutic agent and one or more additives selected from heparin, heparan sulfate, dextran and dextran sulfate, and physiologically-acceptable salts thereof. The one or more additives can be present in an amount effective to increase the rate of release of the water-insoluble therapeutic agent from the coating layer. The implantable medical device structure can be an expandable structure such as a balloon or stent. Also described are methods of making and using such implantable medical devices and coating layers.
