In the field of vascular disease, restenosis refers to the re-growth of tissue within a blood vessel which as been treated with angioplasty or stent placement, such that the blood vessel becomes occluded shortly after pre-existing blockages are cleared. Whether blood vessels are treated with angioplasty alone, bare metal stents or drug eluting stents, restenosis is likely. To combat restenosis, various compounds have been applied to treated blood vessel walls at the time of initial treatment. These compounds includes rapamycin and paclitaxel and various derivatives of these compounds. Typically, these compounds are delivered to the blood vessel wall through balloons or through a drug-eluting compound on the stent. Drug-eluting stents appear to forestall restenosis, and late term thrombosis is a significant complication of drug eluting stents which must eventually be treated, perhaps with balloon delivery of additionally therapeutic agent. Balloon delivery through various mechanisms has been proposed, including (1) coating balloons with a therapeutic compound and then inflating them within a lesion to press the therapeutic compound into contact with the surrounding blood vessel wall and (2) passing a therapeutic compound through the porous wall of a balloon while the balloon is inflated within the lesion in order to infuse the therapeutic compound into the blood vessel wall. For compounds such as paclitaxel, these techniques appear useful at least to the extent that clinical experimentation is warranted. However, due to inherent properties of rapamycin and its analogs or derivatives, e.g. hydrophobicity, direct delivery of these drugs from amorphous or crystalline coatings on the surface of an angioplasty balloon is inefficient.
USPTO Backgrounds
USPTO Backgrounds