Methods are provided for loading polymeric regions of medical devices with therapeutic agents. In these methods, a polymeric region of a medical device is first pretreated with a solvent system. Subsequently, therapeutic-agent-containing particles are impacted into the pretreated polymeric region at a velocity that is effective to at least partially embed the particles within the pretreated polymeric region. The pretreatment step parameters (e.g., the particular solvent system employed, amount of time that the solvent system contacts the polymeric region, etc.) are typically selected such that the surface tack of the polymeric region is increased. Consequently, the depth, the amount, or both the depth and the amount of the particles that become at least partially embedded in the polymeric region is/are typically increased, relative to what would be achieved in the absence of the pretreatment step. Also provided are medical devices made by such methods.