An improved process for coating implantable medical devices utilizes a number of techniques for improving the stability of therapeutic agents contained within the coating. In one embodiment, the process comprises: (a) applying a primer coating on the implantable medical devices, including the application of a parylene layer and annealing the parylene layer to reduce autoxidation initiators (b) preparing a basecoat solution comprising polymers and a therapeutic agent and applying the basecoat solution to the implantable medical devices coated with parylene, the basecoat solution being prepared with and applied utilizing a process to reduce the presence and exposure of the basecoat solution to oxygen, raising the glass transition temperature of the therapeutic agent and creating a coating morphology to protect the therapeutic agent from autoxidation (c) preparing a topcoat solution comprising at least one polymer and applying the topcoat solution to the implantable medical devices coated with the basecoat solution, the topcoat solution being prepared with and applied utilizing a process to reduce the presence and exposure of the topcoat solution to oxygen, raising the glass transition temperature of the therapeutic agent and creating a coating morphology to protect the therapeutic agent from autoxidation and (d) finally processing the implantable medical devices, including inspecting, packaging and sterilizing the coated medical devices, the final processing including protecting the therapeutic agent from autoxidation, reducing the presence of and exposure of all materials to five radicals and reducing the presence of and exposure of all materials to oxygen.
