DEVICE FOR DRUG DELIVERY

摘要

The invention relates to a medical device, such as a stent or a balloon catheter that includes an expandable body portion which has an exterior surface that contacts a vessel wall during treatment. The medical device includes a first coating disposed over at least a portion of the exterior surface. The first coating includes a therapeutic substance that is intended for controlled release from the exterior surface. The medical device further includes a second coating overlaying at least a substantial portion of the first coating. The second coating includes a material that is generally impervious to elution of the therapeutic substance therethrough when the body portion is inserted into the vessel lumen. The material of the second coating is relatively inelastic so that the second coating fractures during expansion of the body portion to allow elution of the therapeutic substance through fissures formed in the second coating.