Sterilization of medical devices with enhanced antimicrobial properties

Abstract

The present invention relates to a sterilized medical dressing for treating wounds comprised of a polymer sponge containing an antimicrobial agent and a silicon adhesive secured to the dressing surface. The dressing can be exposed initially to gamma radiation and later sterilized by ethylene oxide or alternatively it can be sterilized by ethylene oxide and later irradiated by gamma radiation. z The sponge dressing can also contain at least one biofilm reducing agent, at least one chelating agent and an ionic and non-ionic surfactant.

What is claimed is: 
     
         1 . A sterile device for medical use comprising a shaped polymer structure containing an antimicrobial agent, said shaped polymer structure having been subjected to both gamma radiation and ethylene oxide, and a silicon adhesive secured to said structure surface to hold said structure in a substantially fixed position. 
     
     
         2 . The sterile device of  claim 1  wherein said polymer is taken from a group of polymers consisting of polyvinyl formal, polyvinyl acetal, polyurethane, or a mixture of polymers. 
     
     
         3 . The sterile device of  claim 1  wherein said device is a sponge having a morphology characterized by an average pore throat diameter of 0.5-500 μm, a fluid retention of 5.5-25.0 mL fluids/g porous material, a density of 0.05-0.15 g polymer/cm 3  porous material, and a porosity of 60% to 99.5%. 
     
     
         4 . The sterile device of  claim 1  wherein said device is a dressing sponge which contains biofilm reducing agents taken from a group consisting of amylase enzymes (e.g. amyloglucosidase, bacterial amylo novo), protease enzymes (e.g. savinase and everlase) fibrinolytic agents (e.g. plasmin, streptokinase, and nattokinase, and TrypLE), deoxyribonuclease I, glycoside hydrolase dispersin B, and cellulase. 
     
     
         5 . The sterile device of  claim 1  wherein said device is a stent. 
     
     
         6 . The sterile device of  claim 5  wherein said stent is constructed of polyurethane. 
     
     
         7 . The sterile device of  claim 5  wherein said stent is constructed of polyvinyl acetal. 
     
     
         8 . The sterile device of  claim 1  wherein said stent is constructed of polyurethane. 
     
     
         9 . The sterile dressing of  claim 1  wherein said device is constructed of polyvinyl acetal. 
     
     
         10 . A sterile dressing for treating wounds comprised of a polymer sponge containing at least one antimicrobial agent and a silicon adhesive secured to a surface of said polymer sponge, said dressing being exposed to gamma radiation for a period suitable to apply gamma radiation ranging from about 5 to about 36 kilogray to said sponge dressing and to a standard treatment of ethylene oxide, and containing at least one biofilm reducing agent. 
     
     
         11 . The sterile dressing of  claim 10  wherein said sponge contains chelating agents to sequester the metals that crosslink polysaccharides in the biofilm taken from a group consisting of ethylenediaminetetraacetic acid (EDTA), citrates, phosphonates and phosphonic acids. 
     
     
         12 . The sterile device of  claim 1  wherein said dressing is constructed of polyurethane. 
     
     
         13 . The sterile dressing of  claim 1  wherein said dressing is constructed of polyvinyl acetal. 
     
     
         14 . A process of sterilizing a polymer medical device comprising the steps of
 a) applying an antimicrobial agent to said medical device;   b) exposing the treated medical device to gamma radiation to obtain sterilization; and   c) treating the radiated device with an EO sterilization having a cycle temperature of about 108° F., a cycle humidity of about 30% RH and an EO sterilant concentration of about 600 mg/L   
     
     
         15 . The process of  claim 14  wherein said medical device is a foamed polymer sponge dressing. 
     
     
         16 . The process of  claim 15  wherein in step b} gamma radiation is applied in an amount ranging from about 5 to about 36 kilogray to said sponge dressing; 
     
     
         17 . The process of  claim 14  wherein said medical device is a sterile dressing for treating wounds. 
     
     
         18 . The process of  claim 17  wherein said sterile dressing is constructed of polyurethane. 
     
     
         19 . The process of  claim 17  wherein said sterile dressing is constructed of polyvinyl acetal. 
     
     
         20 , The process of  claim 14  after step c) packing said device in a sealed disposable package. 
     
     
         20 . The dressing of  claim 19  wherein said polymer dressing is taken from a group of polymers consisting of polyvinyl formal, polyvinyl acetal, polyurethane, and a mixture of said polymers.