Implantable or insertable medical device resistant to microbial growth and biofilm formation

Disclosed are implantable or insertable medical devices which provide resistance to microbial growth on and in the surroundings of the device and resistance to microbial adhesion and biofilm formation on the gadget. Specifically, the invention discloses implantable or insertable medical instruments which comprise a minumum of one biocompatible matrix polymer region, an antimicrobial agent for supplying resistance to microbial growth and also a microbial adhesion/biofilm synthesis inhibitor for inhibiting the attachment of germs and the synthesis and accumulation of biofilm on the surface of their medical device. Also disclosed are methods of fabricating such devices under conditions which substantially prevent preferential partitioning of any one of said bioactive agents to a surface of this biocompatible matrix polymer and also substantially prevent chemical modification of stated bioactive agents.

 

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BACKGROUND

 

 
Implantable or insertable medical devices like stents made of metallic, polymeric or a composite of metallic and polymeric materials frequently occlude because of microbial colonization and adhesion. This issue is particularly prevalent withmedical devices which are adapted to remain planted for a comparatively long time, i.e., from approximately 30 days to approximately 12 months or more. Microbes such as germs frequently colonize on and around the medical device and, on attaching to surfaces of thedevice, proliferate and form aggregates within a complex matrix comprising extracellular polymeric substances, normally polysaccharides. The mass of connected microorganisms and the related extracellular polymeric substances is generally referredto as a biofilm or slime. Antimicrobial agents have difficulty penetrating biofilms and killing or inhibiting the growth of the microorganisms within the biofilm. The colonization of the microbes on and around the device and also the synthesis ofthe biofilm barrier eventually lead to encrustation, occlusion and collapse of the device.
 

 
Previous approaches to lessen this issue have included the use of low surface energy materials such as Teflon.RTM. In implantable medical devices and the use of surface coatings on such medical apparatus. Surface coatings possess typicallycomprised only antimicrobials or even 1-2 antibiotics.
 

 

By Way of Example, U.S. Pat.

No. 5,853,745 discloses an implantable medical device having a durable protective coating layer within an antimicrobial coating layer. The coat layers are formed by employing an antimicrobial coating layer to at least aportion of the face of their medical device, employing a durable coating over the antimicrobial coating layer, and employing a heated coating layer within the durable coating layer.
 

 

U.S. Pat.

No. 5,902,283 reveals a non-metallic antimicrobial impregnated implantable medical device in which the antimicrobial composition is applied to the device under conditions in which the antimicrobial article illuminates the material ofthe device.
 

 

U.S. Pat.

No. 5,772,640 discloses polymeric medical devices that were impregnated and/or coated with chlorhexidine and triclosan by dipping or soaking the medical apparatus in a solution of a hydrophobic or hydrophilic polymer containingchlorhexidine and triclosan.
 

 

Published International Application No.

WO 99/47595 discloses a plastics material which may be utilised in certain medical programs containing an acrylic polymer containing 5-50percent of a rubbery copolymer and a biocidal compound. The patent alsodiscloses adding antimicrobial agent to the polymer melt by way of a liquid injection method.
 

 

U.S. Pat.

No. 5,679,399 discloses membranes which may include one or more permeable or semipermeable layers containing substances such as biocides. The layers allow the transmission of environmental fluids inwardly and the outward dispersionof the biocides. These membranes may also incorporate a sealing or coating to entrap agents like biocides therein.
 

 
Of the previous tactics, coatings have fulfilled the best success because of their proximity to the bacterial environment and hence their effective approach to preventing bacterial colonization and attachment. But this approach hasproven insufficient because of the prospect of bacterial resistance to one narrow spectrum active representative, since the quantity of active agent which can be integrated into such coatings is usually low, and since externally coated tubular devicesrelease active representatives into the environment external to the device but not intraluminally.
 

 
In an effort to alleviate the foregoing and other disadvantages of the prior art, Applicants have developed an implantable or insertable medical device acceptable for long-term implantation and a method for manufacturing such a device, whereas thedevice offers immunity to microbial growth on and around the device and biofilm formation on the device. The device of the present invention, hence, overcomes the disadvantages related to the usage of coatings as discussed previously, and providesa reduced danger of biofilm fouling that finally results in encrustation, occlusion and collapse of the device.
 

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