Method For Coating Implantable Devices

Abstract

A method of forming a coating for an implantable medical device, such as a stent, is provided which includes applying a composition to the device in an environment having a selected pressure.

1 . A method of forming a coating for an implantable medical device, comprising 
 inserting the device into a chamber;    adjusting the pressure of the chamber to a pressure greater than ambient pressure;    followed by applying a composition comprising a solvent to the implantable device while the device is disposed in an environment having the pressure at greater than ambient pressure, wherein the pressure and temperature in the chamber are always less than the critical pressure and temperature of the solvent during the adjustment of the pressure and during the coating of the device.    
     
     
         2 . The method of  claim 1  wherein the composition comprises a polymer dissolved in the solvent and optionally a therapeutic substance added thereto.  
     
     
         3 . The method of  claim 2  wherein the therapeutic substance is 
 an antiproliferative antineoplastic, antiinflammatory, antiplatelet, anticoagulant, antifibrin, antithrombin, antimitotic, antioxidant, or a combination of these; or    an antibiotic combined with an antiproliferative antineoplastic, antiinflammatory, antiplatelet, anticoagulant, antifibrin, antithrombin, antimitotic, antioxidant, or a combination of these.    
     
     
         4 . The method of  claim 2  wherein the solvent comprises a compound selected from chloroform, acetone, water, buffered saline, dimethylsulfoxide, propylene glycol methyl ether, isopropyl alcohol, n-propyl alcohol, methanol, ethanol, tetrahydrofuran, dimethylformamide, dimethyl acetamide, benzene, toluene, xylene, hexane, cyclohexane, heptane, octane, nonane, decane, decalin, ethyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, butanol, diacetone alcohol, benzyl alcohol, acetone, 2-butanone, cyclohexanone, dioxane, methylene chloride, carbon tetrachloride, tetrachloroethylene, tetrachloroethane, chlorobenzene, 1,1,1-trichloroethane, formamide, and their combinations.  
     
     
         5 . The method of  claim 1  wherein the act of applying comprises spraying the composition on the implantable device.  
     
     
         6 . The method of  claim 1  wherein the implantable device is a stent and the act of applying comprises spraying the composition while rotating the stent about the longitudinal axis of the stent.  
     
     
         7 . The method of  claim 1  wherein the implantable device is a stent and the act of applying comprises spraying the composition while moving the stent in a linear direction along the longitudinal axis of the stent.  
     
     
         8 . The method of  claim 1  wherein the composition includes a therapeutic substance and wherein the temperature of the chamber is adjusted to a temperature that does not adversely affect the therapeutic substance.  
     
     
         9 . The method of  claim 8  wherein the composition comprises a polymer dissolved in the solvent.  
     
     
         10 . A method of forming a coating for an implantable medical device, comprising 
 i) inserting the device into a chamber;    ii) adjusting the pressure of the chamber to a pressure greater than ambient pressure;    iii) followed by applying a composition comprising a solvent to the implantable device while the device is disposed in an environment having the pressure at greater than ambient pressure, wherein the pressure and temperature in the chamber are in a range of values such that the solvent evaporates during the formation of the coating on the device.