Stent And Delivery System With Reduced Chemical Degradation

Abstract

Stents and delivery systems with reduced chemical degradation and methods of sterilizing the same are disclosed.

What is claimed is: 
     
         1 . A stent comprising:
 a polymeric portion;   optionally, a drug; and   a chemical degradation-reducing substance that reduces or prevents chemical degradation of a polymer of the polymeric portion and/or the optional drug, the chemical degradation arising from exposure to radiation during sterilization;   wherein the substance comprises a polymeric or oligomeric antioxidant or free radical scavenger selected from the group consisting of polyazomethine, high sulfate agar oligomers, and combinations thereof   
     
     
         2 . The stent of  claim 1 , wherein the radiation comprises e-beam or gamma radiation. 
     
     
         3 . The stent of  claim 1 , wherein the polymeric portion comprises a biostable or bioabsorbable polymer, the substance being dispersed within the polymeric portion. 
     
     
         4 . The stent of  claim 1 , wherein the polymeric portion is at least a part of a material from which the stent is formed, and wherein the substance is dispersed within the polymeric portion. 
     
     
         5 . The stent of  claim 1 , wherein the stent comprises a metallic material or an alloy. 
     
     
         6 . The stent of  claim 1 , wherein the polymeric portion is at least a part of a coating on the stent, and the substance is dispersed within the polymeric portion. 
     
     
         7 . The stent of  claim 6 , wherein the polymeric portion is a substance layer of the coating, the substance being dispersed within the substance layer of the coating, and the substance layer being disposed above and/or below a layer of the coating comprising the drug and a polymer. 
     
     
         8 . The stent of  claim 1 , wherein substance further comprises a free radical scavenger or antioxidant selected from the group consisting of L-ascorbate, Vitamin E, herbal rosemary, sage extracts, butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate, tertbutylhydroquinone, and combinations thereof 
     
     
         9 . The stent of  claim 1 , wherein the substance comprises polyazomethine. 
     
     
         10 . The stent of  claim 1 , wherein some of the polymeric or oligomeric antioxidant or free radical scavenger are bonded or grafted to a polymer of the polymeric portion which may be the polymer of the polymeric portion for which chemical degradation is reduced by the substance, or a different polymer. 
     
     
         11 . A stent delivery assembly optionally comprising a drug, and comprising a polymeric portion, the polymeric portion comprising a chemical degradation-reducing substance that reduces or prevents chemical degradation of a polymer of the polymeric portion and/or the optional drug, the chemical degradation arising from exposure to radiation during sterilization;
 wherein the substance comprises a polymeric or oligomeric free radical scavenger or antioxidant selected from the group consisting of polyazomethine, high sulfate agar oligomers, and combinations thereof   
     
     
         12 . The assembly of  claim 11 , wherein the radiation comprises e-beam or gamma radiation. 
     
     
         13 . The assembly of  claim 11 , wherein the polymeric portion comprises a catheter, the substance being dispersed within a polymer of the catheter which may be the polymer of the polymeric portion for which chemical degradation is reduced by the substance, or a different polymer. 
     
     
         14 . The assembly of  claim 11 , wherein the polymeric portion comprises a coating above a catheter, stent delivery balloon, or restraining sheath disposed over a stent disposed over a catheter, the coating including the substance dispersed within the coating. 
     
     
         15 . The assembly of  claim 11 , wherein the polymeric portion comprises a restraining sheath disposed over a stent, the substance being dispersed within a polymer of the restraining sheath which may be the polymer of the polymeric portion for which chemical degradation is reduced by the substance, or a different polymer. 
     
     
         16 . The assembly of  claim 11 , wherein the polymeric portion comprises a balloon, the substance being dispersed within a polymer of the balloon which may be the polymer of the polymeric portion for which chemical degradation is reduced by the substance, or a different polymer. 
     
     
         17 . The assembly of  claim 11 , wherein the chemical degradation comprises reactions of free radicals with the polymer of the polymeric portion, the substance reducing or preventing the reactions. 
     
     
         18 . The assembly of  claim 11 , wherein the substance further comprises a free radical scavenger or antioxidant selected from the group consisting of L-ascorbate, Vitamin E, herbal rosemary, sage extracts, butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate, tertbutylhydroquinone, and combinations thereof 
     
     
         19 . The assembly of  claim 11 , wherein the substance comprises polyazomethine. 
     
     
         20 . The assembly of  claim 11 , wherein some of the polymeric or oligomeric antioxidant or free radical scavenger are bonded or grafted to a polymer of the polymeric portion, which may be the polymer of the polymeric portion for which chemical degradation is reduced by the substance, or a different polymer .