Thermal Treatment Of An Implantable Medical Device

Abstract

A method of manufacturing an implantable medical device, such as a drug eluting stent, is disclosed. The method includes subjecting an implantable medical device that includes a polymer to a thermal condition. The thermal condition can result in reduction of the rate of release of an active agent from the device subsequent to the implantation of the device and/or improve the mechanical properties of a polymeric coating on the device.

1 . A method of manufacturing a stent having a body made at least in part from a polymer component, the method comprising exposing the polymer component to a temperature equal to or greater than the glass transition temperature of the polymer component. 
     
     
         2 . The method of  claim 1 , wherein the stent is a biodegradable stent. 
     
     
         3 . The method of  claim 1 , wherein the temperature is
 (a) equal to the glass transition temperature of the polymer component plus the melting temperature of the polymer component, divided by 2;   (b) equal to 0.9 times the melting temperature of the polymer component, wherein the melting temperature of the polymer component is expressed in Kelvin;   (c) equal to or greater than the crystallization temperature of the polymer component;   (d) below the melting temperature of the polymer component; or   (e) above the melting temperature of the polymer component.   
     
     
         4 . The method of  claim 1 , wherein the polymer component includes poly(lactic acid). 
     
     
         5 . The method of  claim 1 , wherein the polymer component includes a block copolymer or a graft copolymer, and wherein a moiety of the block copolymer or the graft copolymer is poly(lactic acid). 
     
     
         6 . A method of manufacturing an implantable medical device, comprising:
 forming a first region including a first polymer on the device;   forming a second region of a second polymer on the device, the second region including an active agent, the first region being over or under the second region; and   heating   (i) the first polymer to a temperature equal to or above the glass transition temperature of the first polymer, or   (ii) the second polymer to a temperature equal to or above the glass transition temperature of the second polymer.   
     
     
         7 . The method of  claim 6 , wherein the first polymer has a glass transition temperature greater than the second polymer. 
     
     
         8 . The method of  claim 6 , wherein the second polymer has a glass transition temperature greater than the first polymer. 
     
     
         9 . The method of  claim 6 , wherein the temperature is
 (a) equal to the glass transition temperature of the first polymer plus the melting temperature of the first polymer component, divided by 2;   (b) equal to the glass transition temperature of the second polymer plus the melting temperature of the second polymer component, divided by 2;   (c) equal to 0.9 times the melting temperature of the first polymer or the second polymer, wherein the melting temperature is expressed in Kelvin;   (d) equal to or greater than the crystallization temperature of the first or second polymer;   (e) below the melting temperature of the first or second polymer; or   (f) above the melting temperature of the first or second polymer.   
     
     
         10 . The method of  claim 6 , wherein the first or second polymer includes poly(lactic acid). 
     
     
         11 . The method of  claim 6 , wherein the first or second polymer includes a block copolymer or a graft copolymer, and wherein a moiety of the block copolymer or the graft copolymer is poly(lactic acid). 
     
     
         12 . A method of manufacturing an implantable medical device, the device including a polymer and a drug, the method comprising treating the device to a temperature greater than ambient temperature for a duration of time, wherein the temperature and the duration of exposure are sufficient to decrease the release rate of the drug from the device after the device has been implanted into a biological lumen. 
     
     
         13 . The method of  claim 12 , wherein the device includes a coating having the polymer and the drug, the drug being blended in the coating. 
     
     
         14 . The method of  claim 12 , wherein the device is made in whole or in part from the polymer. 
     
     
         15 . The method of  claim 12 , wherein the polymer is biodegradable. 
     
     
         16 . The method of  claim 12 , wherein the device is a stent. 
     
     
         17 . The method of  claim 12 , wherein the treatment does not reduce the total content of the drug carried by the device. 
     
     
         18 . The method of  claim 12 , wherein the standard deviation of the mean release rate of the drug in a 24 hour period is lower than the standard deviation of the mean release rate for a group of devices which have not been exposed to the temperature. 
     
     
         19 . The method of  claim 12 , wherein the drug is rapamycin, 40-O-(2-hydroxy)ethyl-rapamycin, or a functional analog or structural derivative thereof. 
     
     
         20 . The method of  claim 12 , wherein the drug is paclitaxel or docetaxel. 
     
     
         21 . The method of  claim 12 , wherein the polymer includes poly(lactic acid). 
     
     
         22 . The method of  claim 12 , wherein the polymer includes a block copolymer or a graft copolymer, and wherein a moiety of the block copolymer or the graft copolymer is poly(lactic acid).