Therapeutic agent elution control process

Abstract

Medical devices, and in particular implantable medical devices, may be coated to minimize or substantially eliminate a biological organism's reaction to the introduction of the medical device to the organism. The medical devices may be coated with any number of biocompatible materials. Therapeutic drugs, agents or compounds may be mixed with the biocompatible materials and affixed to at least a portion of the medical device. These therapeutic agents or compounds may also further reduce a biological organism's reaction to the introduction of the medical device to the organism. In addition, these therapeutic drugs, agents and/or compounds may be utilized to promote healing, including the prevention of thrombosis. The drugs, agents, and/or compounds may also be utilized to treat specific disorders, including vulnerable plaque. Implantable coated medical devices may be processed through annealing to better control the elution characteristics of the therapeutic agents. Furthermore, annealing leads to better therapeutic agent stability and a larger device shelf-life.

What is claimed is: 
     
         1 . A method for controlling the elution characteristics and stability of at least one therapeutic agent comprising:
 applying a first coating, including a therapeutic dosage of at least one agent and at least one polymeric material to an implantable structure; and   annealing the first coating to a temperature substantially greater than the highest glass transition temperature (T g ) of the at least one polymer.   
     
     
         2 . The method according to  claim 1 , wherein the implantable structure comprises a stent. 
     
     
         3 . The method according to  claim 1 , wherein the implantable structure comprises a stent-graft. 
     
     
         4 . The method according to  claim 1 , wherein the implantable structure comprises an anastomosis device. 
     
     
         5 . The method according to  claim 1 , wherein the therapeutic agent comprises rapamycin. 
     
     
         6 . The method according to  claim 1 , wherein the therapeutic agent comprises Sirolimus. 
     
     
         7 . The method according to  claim 1 , wherein the coating is applied by dipping. 
     
     
         8 . The method according to  claim 1 , wherein the coating is applied by spraying. 
     
     
         9 . The method according to  claim 1 , wherein the coating is applied by spinning. 
     
     
         10 . The method according to  claim 1 , wherein the coating is annealed to a temperature at least 10° C. degrees greater than the greatest glass transition temperature of the at least one polymer. 
     
     
         11 . The method according to  claim 1 , wherein an additional coating is applied after the annealing process to further control the elution rate of the therapeutic agent. 
     
     
         12 . The method according to  claim 1 , further comprising the step of annealing under a vacuum. 
     
     
         13 . The method according to  claim 12 , wherein the vacuum has a preferred pressure of approximately 1 Torr (1 Torr=1 mmHg) or less. 
     
     
         14 . The method according to  claim 12 , wherein the vacuum is applied for greater than one hour. 
     
     
         15 . The method according to  claim 12 , wherein the vacuum is achieved via variable vacuum with N 2  bleeding cycles.