According to an aspect of the present invention, medical devices are provided, which are adapted for implantation or insertion into a subject and which include at least one multilayer region that contains multiple charged layers of alternating charge. The multiple charged layers, in turn, include the following: (i) at least one charged block copolymer (e.g., a charged block copolymer that contains one or more polyelectrolyte blocks) and (ii) at least one charged therapeutic agent (e.g., a charged therapeutic agent that contains one or more polyelectrolyte blocks).