Antimicrobial coatings for medical devices

Abstract

Antimicrobial formulations and coatings for medical devices and processes therefor are disclosed. The formulations include at least one water permeable polymer with at least one antimicrobial agent in a liquid medium and are prepared by wet milling the components and can form antimicrobial coatings having uniformly dispersed particles having an average size of no greater than 50 microns.

What is claimed is: 
     
         1 . A medical device comprising an antimicrobial coating, wherein the coating comprises at least one water permeable polymer and uniformly dispersed particles therein of at least one antimicrobial agent, and wherein the particles and any agglomerations of the antimicrobial agent have an average size of no greater than 50 microns. 
     
     
         2 . The medical device of  claim 1 , wherein the average size is no greater than 20 microns. 
     
     
         3 . The medical device of  claim 2 , wherein the average size is no greater than 5 microns. 
     
     
         4 . The medical device of  claim 1 , wherein the at least one water permeable polymer encapsulates the at least one antimicrobial agent. 
     
     
         5 . The medical device of  claim 1 , wherein the at least one water permeable polymer includes at least one of a polyurethane or a thermoplastic polyurethane elastomer. 
     
     
         6 . The medical device of  claim 1 , wherein the at least one polymer includes at least one of a polyurethane, thermoplastic polyurethane elastomer, polyester, polylactic acid, polyglycolic acid, polytetramethylene glycol, polyacrylamide, polyacrylic acid, polyacrylate, poly(2-hydroxyethyl methacrylate), polyethylene-imine, poly-sulfonate and copolymers thereof. 
     
     
         7 . The medical device of  claim 1 , wherein the at least one polymer has a weight average molecular weight of from about 70,000 to about 120,000 Daltons. 
     
     
         8 . The medical device of  claim 1 , wherein the at least one antimicrobial agent comprises silver sulfadiazine, and wherein the coating has a release profile wherein at least 0.50 micrograms per centimeter (μg/cm) of silver is continuously released after 72 hours. 
     
     
         9 . The medical device of  claim 1 , wherein the coating further comprises chlorhexidine diacetate, and at least 10 μg/cm of chlorhexidine diacetate is continuously released after 72 hours. 
     
     
         10 . The medical device of  claim 1 , wherein the at least one antimicrobial agent comprises a silver-based salt and a polybiguanide salt. 
     
     
         11 . The medical device of  claim 10 , wherein the silver-based salt is silver sulfadiazine, and the polybiguanide salt is chlorhexidine diacetate. 
     
     
         12 . The medical device of  claim 11 , wherein the coating comprises from about 2 weight percent (wt. %) to about 10 wt. % of silver sulfadiazine, wherein the coating comprises at least 9 wt. % of chlorhexidine diacetate, and wherein the coating comprises from about 70 wt. % to about 90 wt. % of the water permeable polymer. 
     
     
         13 . The medical device of  claim 12 , wherein the coating comprises from about 3.5 wt. % to about 7 wt. % silver sulfadiazine. 
     
     
         14 . The medical device of  claim 13 , wherein the coating has a release profile wherein at least 0.50 μg/cm of silver is continuously released after 150 hours. 
     
     
         15 . The medical device of  claim 12 , wherein the coating comprises at least 11 wt. % of chlorhexidine diacetate. 
     
     
         16 . The medical device of  claim 15 , wherein the coating has a release profile wherein at least 10 μg/cm of chlorhexidine diacetate is continuously released after about 150 hours. 
     
     
         17 . The medical device of  claim 1 , wherein the coating has a thickness of between about 20 microns to about 80 microns. 
     
     
         18 . An antimicrobial formulation for coating a medical device prepared according to a process comprising:
 milling at least one water permeable polymer which is dissolved in a liquid medium with at least one antimicrobial agent which is insoluble in the liquid medium to form the antimicrobial formulation in which the at least one water permeable polymer encapsulates the at least one antimicrobial agent; and   adding a primary C 1-6  alcohol to the antimicrobial formulation,   wherein the at least one antimicrobial agent includes a silver-based antimicrobial agent, and wherein the at least one water permeable polymer includes at least one of a polyurethane or a thermoplastic polyurethane elastomer.   
     
     
         19 . The antimicrobial formulation of  claim 18 , wherein the at least one antimicrobial agent includes a combination of the silver-based antimicrobial agent and a polybiguanide or salt thereof. 
     
     
         20 . The antimicrobial formulation of  claim 18 , wherein the at least one antimicrobial agent includes a combination of silver sulfadiazine and chlorhexidine diacetate.