A covered stent includes a generally tubular stent body having inner and outer stent body surfaces. A sleeve of porous material encloses the stent body and has inner and outer portions opposed to the inner and outer stent body surfaces. A therapeutic agent is located along the stent body, the agent being diffusible through the material. A diffusion barrier is located between the inner material portion and the agent along the stent. The diffusion barrier prevents passage of at least a significant amount the agent through the inner portion of the sleeve of porous material. A diffusion restrictor is located between the outer portion of the sleeve of porous material and the agent along the stent. The diffusion restrictor permits passage of the agent through the inner material portion at a therapeutic level.