Drug-delivery endovascular stent and method of use

Abstract

An improvement in drug-eluting stents, and method of their making are disclosed. The surface of a metal stent is roughened to have a surface roughness of at least about 20 μin (0.5 μm) and a surface roughness range of between about 300-700 μin (7.5-17.5 μm). The roughened stent surface is covered with a polymer-free coating of a limus drug, to a coating thickness greater than the range of surface roughness of the roughened stent surface.

1 . In a method for reducing the rate of occurrence and/or extent of restenosis or thrombosis resulting from vascular injury in a subject, relative to that observed by placing at the site of injury, a bare-metal expandable stent formed of interconnected metal filaments, by the step of coating the outer surface of the stent filaments with a polymer carrier containing a limus drug, an improvement which maintains or further reduces the rate of occurrence and/or extent of restenosis or thrombosis relative to that achieved with a polymer-coated, limus-eluting stent, but without the presence of a polymer carrier, comprising
 roughening outer surface regions of the stent filaments to a surface roughness of at least about 20 μin (0.5 μm), and a surface roughness range of between about 300-700 μin (7.5-17.5 μm), and   coating the roughened regions of the stent filaments with a polymer-free coating of the limus drug, to a coating thickness greater than the range of surface roughness of the roughened stent surface.   
     
     
         2 . The improvement of  claim 1 , wherein the stent filaments are roughened to a surface roughness of between about 20-40 μin (0.5 to 1 μm). 
     
     
         3 . The improvement of  claim 1 , wherein the stent filaments are roughened to have a surface roughness range of between about 300-500 μin (7.5-12.5 μm). 
     
     
         4 . The improvement of  claim 1 , said roughening is carried out by abrading the outer surface regions of the stent filaments with a pressurized stream of abrasive particles. 
     
     
         5 . The improvement of  claim 1 , wherein said roughening is carried out by forming a hydrocarbon-film mask over outer surface regions of the stent filaments, selectively removing stent material exposed by the mask, and removing the mask. 
     
     
         6 . The improvement of  claim 1 , wherein said roughening is carried out by laser etching the outer surface regions of the stent filaments. 
     
     
         7 . The improvement of  claim 1 , wherein said roughening is carried out by peening the outer surface regions of the filaments to imprint a pattern thereon. 
     
     
         8 . The improvement of  claim 1 , wherein said coating is carried out by applying a viscous solution of the drug onto the outer surfaces of the stent filament, and drying the applied solution to form a solid drug coating on the stent filaments. 
     
     
         9 . The improvement of  claim 1 , wherein said coating is carried out to apply a final amount of limus drug on the stent between 80 to 240 ug/cm stent length. 
     
     
         10 . The improvement of  claim 10 , wherein said coating is carried out to produce a final drug coating having a thickness between 5 and 15 μm. 
     
     
         11 . The improvement of  claim 1 , wherein the limus drug coating said stent is Biolimus A9. 
     
     
         12 . In a method for administering an anti-restenosis drug from an expandable stent formed of inter connected metal filaments, by coating the outer surface of the stent with a polymer-free limus drug coating, an improvement which reduces the occurrence and/or extent of restenosis or thrombosis, comprising roughening outer surface regions of the stent filaments which are coated by the limus drug, to a surface roughness of at least about 20 μin (0.5 μm), and a surface roughness range of between about 300-700 μin (7.5-17.5 μm). 
     
     
         13 . The improvement of  claim 12 , wherein the stent filaments are roughened to a surface roughness of between about 20-40 μin (0.5 to 1 μm). 
     
     
         14 . The improvement of  claim 12 , wherein the stent filaments are roughened to have a surface roughness range of between about 300-500 μin (7.5-12.5 μm). 
     
     
         15 . The improvement of  claim 12 , wherein the limus drug is Biolimus A9. 
     
     
         16 . An expandable stent for use in reducing the rate of occurrence and/or extent of restenosis or thrombosis, without the inflammatory response produced by a stent having a limus-drug-eluting polymer coating, when the stent is placed at a site of vascular injury, comprising
 an expandable stent body formed of interconnected metal filaments,   formed on outer surface regions of the stent filaments a roughened surface characterized by a surface roughness of at least about 20 μin (0.5 μm), and a surface roughness range of between about 300-700 μin (7.5-17.5 μm), and   carried on the roughened regions of the stent filaments, a polymer-free coating of the limus drug having a coating thickness greater than the range of surface roughness of the roughened stent surface.   
     
     
         17 . The stent of  claim 16 , wherein the stent filaments are roughened to a surface roughness of between about 20-40 μin (0.5 to 1 μm). 
     
     
         18 . The stent of  claim 16 , wherein the stent filaments are roughened to have a surface roughness range of between about 300-500 μin (7.5-12.5 μm). 
     
     
         19 . The stent of  claim 16 , wherein the limus drug is Biolimus A9.