The present invention relates to methods and components for increasing adhesion of an elution control matrix to a polymeric substrate, and medical devices including such components. In an embodiment, the invention includes a medical device including a substrate having a surface, the substrate comprising a polysiloxane, a parylene layer contacting the surface of the substrate, and an elution control matrix contacting the parylene layer, the elution control matrix comprising a polymeric matrix and an active agent dispersed within the polymeric matrix. Other embodiments are included herein.