WO1994011058A1

WO1994011058A1 - Iontophoretic structure for medical devices

Info

Publication number: WO1994011058A1
Application number: PCT/US1993/010911
Authority: WO
Inventors: Fredric L. Milder
Original assignee: Implemed, Inc.
Priority date: 1992-11-12
Filing date: 1993-11-10
Publication date: 1994-05-26
Also published as: US5322520A; US5725817A; US5498248A; EP0678047A1; JP3555684B2; EP0678047A4; JPH08506027A; CA2149216A1; CA2149216C

Abstract

An iontophoretic structure for medical devices is provided that uses controlled electrical current derived from two dissimilar galvanic materials to drive oligodynamic metal ions (38) into solution to kill bacteria on and near the device to which the structure is affixed. In one embodiment, a first galvanic material (32) separated from a second galvanic material (34) by a resistive material (30) produces an anti-bacterial current flow when placed in contact with an electrolytic fluid. In another embodiment, a cylindrical elastomeric catheter (10) incorporates a first and a second galvanic material separated by a resistive material which controls a current flow between the galvanic materials when the catheter is immersed in an electrolytic fluid. The galvanic materials can be dissimilar metal powders embedded in a conductive polymer substrate that forms an iontophoretic composite material, or dissimilar metals arranged in layers (76, 80) separated by a resistive layer (78). In yet another embodiment, the iontophoretic composite material is configured as an infection control sleeve (60) that covers a portion of an ordinary catheter or cannula. Methods of protecting implantable medical devices and body structures with the iontophoretic structures are also provided.

Description

IONTOPHORETIC STRUCTURE FOR MEDICAL DEVICES

FIELD OF THE INVENTION

The invention relates to oligodynamic iontophoresis, an more particularly to an electrically conductive structure fo medical devices that reduces or eliminates bacteria infection by killing bacteria with controlled oligodynami iontophoresis.

BACKGROUND OF THE INVENTION Oligodynamic metals, such as silver, are effective i minute quantities as bacteriostats and bactericides. Th most active form of these oligodynamic metals is as ions i solution. While the precise nature of the bactericida effect is unknown, it is believed to involve altering th function of the cell membrane or linking to the cell's DN to disrupt cell function. The bactericidal action i effective against a broad spectrum of bacteria, including al of the common strains which cause infection. When thes metals are used in the minute concentrations required to kil or stem the growth of bacteria, they do not have an detrimental effect on normal mammalian cells. Silver is used routinely in antibacterial salves, suc as silver sulfadiazine, and has also been used in clinica trials to coat gauze for burn dressings. Medical devices, such as catheters, with silver impregnated in a solubl collagen or polymer coating are also known. After thes catheters are placed, the coating slowly dissolves and th silver is released over time into the environment. Th infection rates with these products are reported to be tw to four times lower than standard catheters.

One catheter that uses silver as an antibacterial agen has had only limited success because the device, consistin of a silver impregnated collagen cuff which is inserted jus below the skin, is difficult to place correctly. The cuf is also expensive, increasing the cost of a central venou catheter almost three-fold. Other catheters for reducin infection rates use well known approaches, most of the varying only in the type and solubility of the silver o silver-alloy coating.

Many of the prior art catheters that use oligodynami metals as bacteriostats fail to adequately prevent infectio for one or more of the following reasons: 1) Silver release from soluble coatings is not always in the same charge stat and often is not charged at all, therefore its bactericida potential is not optimized; 2) With soluble-coated catheters once the coating dissolves, usually over about two week there is no further antibacterial protection; 3) A non soluble silver, silver alloy or silver-oxide coating ca prevent colonization of the catheter to a limited extent, bu the oligodynamic metal is not released into the surroundin fluid or tissue; 4) Due to the substantial change in th catheter placement procedure, the use of these catheter requires additional personnel training; and 5) Althoug infection can enter the body through either the interior o the exterior of the catheter, not all catheters provide bot interior and exterior protection. Furthermore, despite th capability of silver-alloy coated devices to produce a tw to four fold reduction in bacterial colonization, their hig cost greatly detracts from their modest capabilities.

Research from the 1970's onward has been directed towar improving the antibacterial effects of oligodynamic metal by electrically injecting the metal ions into solution. Thi process, known as oligodynamic iontophoresis, is capable o reducing bacterial colonization fifteen to one-hundred fold Iontophoresis describes the movement of ions in a conductiv fluid under the influence of low-strength electric fields and in this context refers to the forcing of ions into conductive fluid environment using minute electric currents For example, if two electrodes made of a metal, such a silver, are introduced into a conductive medium, such a saline, blood or urine, and an electrical potential i applied across the electrodes, silver ions are driven int solution creating an enhanced bactericidal effect. Th current required to safely drive a sufficient amount o silver ions into solution to control infection is in th range of 1 to 400 microAmperes. This current range does no cause localized cell necrosis and it is below the sensory o pain threshold.

Despite its great potential, the oligodynami iontophoresis phenomenon has found limited use in conjunctio with medical devices, although urological or Foley catheter have progressed to animal experiments. With respect to Fole catheters, researchers have identified several deficiencie in prior art devices. Foremost is that the electrodes use to force ions into solution wear out, or corrode, at th interface between air and the conductive medium. Thi problem probably also arises in blood or saline environment as well as urine. Other significant drawbacks with prior ar iontophoretic devices include bulky, current-controlled powe sources required for driving the electrodes; electrod configurations that do not protect both the outside and th inside of the catheter; and manufacturing processes that ar labor intensive.

An example of an infection control catheter that use separate electrodes on the catheter and an external powe supply to drive ions into solution is U.S. Patent No 4,411,648 to Davis. Other prior art oligodynami iontophoresis devices do not use external power supplies For example, U.S. Patent No. 4,886,505 to Haynes, teache placing two metals in direct physical contact to produc electrical currents. The currents produced, however, ar likely to be too large to be safely used and possibly wil alter the pH of the environment. In German Patent Documen DE 3,830,359, two dissimilar metal powders not in electrica contact with each other are embedded in a nonconductiv catheter material, such as electrically insulating polymers Because of the separation of dissimilar metals by a insulator, it is not likely that there is any iontophoresi effect in this device as a result of a potential bein created by the dissimilar metals, except for the possibilit of when a biofil forms on the catheter surface to complet the circuit. Were an electrical circuit to be formed in thi manner, the current density would not be regulated o predictable, and the current produced therefore could b either too high to be safe or too low to be effective. An oligodynamic iontophoresis catheter which uses th properties of metals to generate a current and to form an io barrier for killing bacteria at a localized body entry i disclosed in U.S. Patent No. 4,569,673 to Tesi. Tesi teache placing a strip of an oligodynamic metal on a nonconductiv substrate. The oligodynamic metal acts as a sacrificia galvanic anode and gives off ions when placed in conductiv contact with a dissimilar metal by placing the catheter i an electrolytic solution. Because the conductivity and p of urine, for example, varies over time within the sam person, as well as from individual to individual, it woul be extremely difficult to achieve a specific current densit at a given time with any precision or predictability Additionally, the Tesi device only provides localize infection control. Thus, none of these devices fulfill the promise held ou by oligodynamic iontophoresis for reducing infection in long term indwelling medical devices.

SUMMARY OF THE INVENTION

The present invention provides an iontophoreti structure for a medical device that reduces the risk o infection associated with prolonged medical devic implantation in the body. Specifically, the invention i directed toward meeting performance goals of genera antibacterial effectiveness; minimal electrode corrosion precise control of electrical current; portability of th current source; and ease of manufacture. These performanc requirements can be readily addressed by a number o embodiments in which a controlled electrical current drive oligodynamic metal ions into solution to kill bacteria on an near the iontophoretic structure.

In one embodiment, an iontophoretic structure for medical device includes a first and second galvanic materia separated by a resistive material, which when placed i contact with an electrolytic solution creates a current flo which injects anti-bacterial oligodynamic metal ions into th solution.

In another embodiment, an elastomer incorporates a firs and a second galvanic material separated by resistiv material which controls a current flow between the galvani materials when the elastomer is immersed in an electrolyti fluid. The first and second galvanic materials can be meta powders in a conductive polymer that forms a composit material which may be dip-coated over an existing cathete or extruded to form the catheter itself. Alternatively, th galvanic materials can be configured in layered structures, wherein each metal layer is separated from the other by resistive layer. The layered structures can be placed o surfaces of the catheter where antibacterial action i desired. In another embodiment, two dissimilar metal powder embedded in a conductive polymer substrate create a infection control sleeve that covers an ordinary catheter. When the sleeve is placed in an electrolytic fluid t complete a circuit between the metal powders, metal ions ar driven into solution where they have an antibacterial effect. This embodiment is also useful as a catheter introduce sheath.

In yet another embodiment, a method is provided fo giving an implantable medical device antibacterial propertie by placing an iontophoretic structure on its surface prio to implantation. The iontophoretic structure can be eithe a coating including two dissimilar metal powders in conductive polymer substrate, or a layered structure havin two dissimilar metal layers separated by a conductive layer

In still another embodiment, a method is provided fo protecting a natural body structure with an iontophoreti structure comprising two dissimilar metal powders in conductive base material. The iontophoretic structure i painted onto the body structure when the base material is i a softened or uncured state. The base material is the allowed to harden or cure.

DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from th following detailed description taken in conjunction with th accompanying drawings in which: Fig. 1 is a perspective view of an iontophoresi catheter incorporating a composite material comprising meta powders in a conductive elastomeric matrix;

Fig. 2 is a partial sectional view of the iontophoresi catheter of Fig. 1; Fig. 3 is a depiction of the iontophoresis effec created by the composite material in the catheter of Fig. 1

Fig. 4 is a perspective view of a pacing lead coate with the composite material of Fig. 1;

Fig. 5 is a perspective view of an artificial hip join partially coated with the composite material of Fig. 1;

Fig. 6A is a perspective view of an infusion pump coate with the composite material of Fig. 1;

Fig. 6B is a perspective view of a tooth coated with th composite material of Fig. 1; Fig. 7 is a perspective view of a catheter with a iontophoresis infection control sheath;

Fig. 8 is a perspective view of a catheter with a iontophoresis infection control introducer sheath;

Fig. 9 is a perspective view of an iontophoresi catheter having a plurality of layered electrodes; Fig. 10 is a perspective view of an alternativ embodiment of an iontophoresis catheter having a pluralit of layered electrodes arranged in strips; and

Fig. 11 is a partial sectional view of the iontophoresi catheter of Fig. 10.

DETAILED DESCRIPTION OF THE INVENTION Iontophoretic structures in accordance with th invention may be divided into two categories: a composit material used to coat a medical device, or a plurality o discrete layered electrodes placed on the medical device, both of which categories are disclosed hereinbelow. Th medical device can be a short-term, long-term, or permanen implant and includes such devices as: urinary catheters, vascular access catheters and introducer sheaths, flui introduction tubing and fittings such as intra-venous tubing, urinary drainage bags and tubing, chest drainage tubes, infusion pumps, pacing leads, tracheotomy tubes, ventilatio tubes, prosthetic joints, heart valves, wound dressings, orthopedic pins or plates, or any other medical device use in an environment or application where anti-bacteria properties are a consideration. However, because urinar catheters are an especially attractive application for th iontophoretic structures, the ensuing detailed descriptio is directed thereto. With respect to the first category of iontophoreti structure for a medical device, Fig. 1 illustrates a exemplary iontophoresis catheter 10 that uses the composit material approach to kill bacteria. The iontophoresi catheter 10 is substantially identical to a normal or non infection controlling catheter in that it is a hollo flexible tube comprising an elastomeric wall 12 having a inner surface 14 and an outer surface 16, a proximal end 18 and a distal end 20. The generally cylindrical inner surfac 14 defines a lumen 22 for the passage of fluid. Both th proximal end 18 and the distal end 20 are provided with on or more openings 26 to allow the fluid to be introduced or evacuated from the lumen 22. The distal end 20 is shaped to facilitate insertion or placement of the iontophoresis catheter 10 into the body. The iontophoresis catheter 10 may also be fitted with a retention device 28, such as a balloon fitting, to prevent unintentional withdrawal of the iontophoresis catheter 10 from the body.

Fig. 2 is a partial sectional view of the iontophoresis catheter 10 of Fig. 1, taken along the line A-A' , that depicts details of a composite material comprising galvanic materials, such as metal powders, in a conductive elastomeric matrix 30 that distinguishes the iontophoresis catheter 10 from prior art catheters. The wall 12 of the catheter comprises the conductive base material 30, and a first and a second dissimilar metal powder, 32 and 34 respectively. The base material 30 is a conductive polymer similar to that used in static-proof bags for packaging charge-sensitive electronics in which the conductivity (resistivity) is controlled to a predetermined value by its composition. Exemplary conductive polymers can be made from polymers including polyvinyl, polyester, polyethylene, or a naturally conductive polyvinylidene fluoride. When loaded with carbon or other conductive fillers, for example, these polymers can be made conductive and thereby used as the base material 30 for an iontophoresis catheter 10. Exemplary first and second metal powder combinations having an electrochemical half-cell potential difference include silver and gold, silver and copper, or silver and platinum mixed into the polymer at very low volume concentrations prior to extrusion fabrication of the composite catheter 10. Although these exemplary powders are relatively expensive, they are used in such minute quantities that their use does not adversely impact overall cost of the iontophoresis catheter 10.

For catheter applications in which the elastomeric wall 12 is extruded, it is feasible to make the entire wall 12 from the composite material 30, 32, 34. However, Foley catheters which are typically made of latex and/or silicone rubber are not extruded, but are generally dip-cast, and finish-coating in a final dip is a natural processing step in their manufacture. Therefore, the iontophoresis catheter 10 can be made by finish-coating it with the composite material 30, 32, 34. Since rubber is generally inferior to plastic in terms of infection rates, overcoating with a castable plastic is advantageous in and of itself.

When the composite catheter 10 is placed in contact wit or immersed in a fluid that is electrolytic, such as saline, blood, drug preparations, or urine, the first and second metal powders 32, 34 become an array of small batteries. Specifically, each powdered metal granule embedded in the base material 30 that makes contact with the electrolytic fluid 24 becomes either an anode or a cathode, depending on the particular metals chosen as the first and second metal powders 32, 34.

Referring to Fig. 3, a depiction of the iontophoresis effect created by the composite material 30, 32, 34 in the catheter of Fig. 2 is shown. The first and second metal powders 32, 34 act as electrodes and create a voltag potential therebetween, whereby electrons 36 migrate throug the base material 30 and generate an electric current. Meta ions 38 are thus driven into the conductive fluid 24 b iontophoresis. The electric current is regulated by th quantity and nature of metal powder 32, 34 embedded in th base material 30 and by the conductivity of the base material 30. These factors are adjusted so that the current an ultimate metal ion densities are in an efficacious and saf range by use of the following formula: j ( ^AMI) = JL m^f -^2/3 CM² ) 4rp -2/₃_-

wherein: "I" is the total average current per unit surface are (amperes per

; "p" is the volume resistivity of the conductive bas material 30 (ohm-cm) ;

"r" is the average metal powder granule radius (cm) ; "V" is the voltage produced by the two dissimilar metal powders 32, 34 in the electrolytic fluid; and

"L" is the metal powder volume loading of the bas material as a fraction (ie 0-1) .

With respect to the above formula, the metal powders ar assumed to be of the same granule size and of the same volum loading. In practice, they do not have to be the same siz and volume loading. To achieve a current density between 10^' to 10'⁶ Amperes per mm², which is the desired range to b bacteriostatic or bactericidal and yet not be so high as t cause pH changes or other deleterious mammalian cel reactions, the following exemplary values can be used in th above equation to define the composite materia specifications:

V = 0.12 volts (for silver and gold in an NaC electrolyte) ; r = 10-³cm; p = 1.5 X 10⁶ to 1.5 X 10⁴ ohm-cm; and L = 0.01.

An iontophoresis catheter 10 incorporating the abov described composite material has numerous advantages over th prior art with respect to effectiveness, controllability, an ease of use. Foremost, bacterial potency is maximize because metal is guaranteed to go into solution as ions, thu producing a minimum ten-fold reduction in bacteria colonization rate. Also, the iontophoresis catheter 10 doe not need an external current source or controller because th iontophoresis current is self-generating and self-regulating

Furthermore, because the metal powders 32, 34 (electrodes are dispersed through the base material 30, and because th current level is very low, the electrodes are functional fo months of use. There is also no place in the circuit wher corrosion of the electrodes at the air/electrolyte interfac - 14 -

Fig. 10 depicts an alternative configuration of th iontophoresis catheter 70, wherein the plurality of layere structures 72 are bands that surround the wall 12 Alternatively, the layered structures 72 can be a pluralit of longitudinal strips. The embodiments of Figs. 9 and 1 permit selective placement of a layered structure 72 on a isolated region of the wall 12, or distribution of th layered structures 72 on the entire wall 12.

Referring to Fig. 11, a partial cross section of th iontophoresis catheter 70 of Fig. 10 along the line B-B' i shown, wherein the layered structures 72 are bands adhere to the inner surface 14 and outer surface 16 of the wall 12 Each layered electrode 72 comprises a first metal electrod 76, a resistive layer 78, and a second metal electrode 80 As with the iontophoresis catheter 10 of Fig. 1, the metal are biocompatible and form an electrical potential differenc between them in an electrolytic fluid. Whereas, in th iontophoresis catheter 10 of Fig. 1 the conductiv (resistive) base material 30 regulates the current flo between the first and second metals 32, 34, in thi embodiment the (conductive) resistive layer 78 regulates th current flow between the dissimilar metals of the first an second electrodes 76, 80.

For the iontophoresis catheter 70 of Figs. 9 and 10 wherein the first and second metal electrodes 76, 80 of th layered structures 72 have a 1 volt potential between them a current density of 10"⁸ Amperes per mm² results if th thickness of the resistive layer 78 is approximately 1 micrometers and has a bulk conductivity of 10¹¹ Ohm-cm and th exposed area of each of the electrodes 76, 80 in the layere structures 72 is the same. Typical combinations of metal used for the first and second metal electrodes 76, 8 generate between 0.1 to 2 Volts. Therefore, the thicknes of the above described resistive layer 78 can be between and 20 micrometers. Many other combinations of conductivit - 11 - can cause the entire catheter to become non-functional wit regard to its infection resistance. Finally, there is n change in procedure for placing or maintaining th iontophoresis catheter 10 because it is in many way virtually identical to existing non-infection control device in size and shape.

As previously discussed, the composite material approac finds ready application on numerous other medical device where antibacterial properties are desirable. Fig. 4 is a illustration of the composite material 30, 32, 34 used t protect a pacing lead 40. The pacing lead 40 connects th heart tissue to the control and monitoring apparatus of cardiac pacemaker (not shown) via a wire 42 and an electrod 44 in the tissue. The wire 42 is shown covered with th composite material 30, 32, 34. Fig. 5 is a depiction of th composite material 30, 32, 34 used with a prosthetic device such as an artificial hip joint 46. The shaft 48 is show coated with composite material 30, 32, 34 and implanted int a femur 50. Fig. 6A shows an infusion pump 52 coated wit the composite material 30, 32, 34 and connected to tubing 5 which may also be coated.

The composite material 30, 32, 34 can also be coate onto a natural body structure 55, such as a tooth, a illustrated in Fig. 6B. This is accomplished by painting th composite material 30, 32, 34 onto the surface to b protected while the base material 30 is in a liquified o softened state and then letting the base material 30 harden In an alternative embodiment the base material 30 is binar adhesive, such as a catalytic, two-part, conductive epox mix.

With further regard to catheters, a vascular access add on device that benefits from the composite material approac for an iontophoretic structure is shown in Fig. 7, wherei an ordinary catheter 56 is shown fitted with an infectio control kit 58 incorporating the composite material 30, 32 34. The infection control kit 58 is an after-market devic - 12 - which includes a replaceable iontophoretic infection control sleeve 60 and an iontophoretic Luer adaptor 62 for connecting the proximal end 18 of the catheter 56 to intravenous (I.V.) tubing 64. The sleeve 60, made of or coated with the composite material 30, 32, 34 slips over the outer surface 16 of the catheter 56 to be inserted the body. The sleeve 60 covers only a short section of the catheter 56 near its proximal end 18, but is long enough to enter the body wherein moisture will activate the iontophoresis process. The sleev 60 thus protects the catheter surface 16 from infection. The Luer adaptor 62 may also be made of or coated on the inner surface with the composite material 30, 32, 34 to protect the inner surface 14 of the catheter 56 from bacterial colonization progressing down to the catheter 56 from the inside of the I.V. tube 64. The sleeve 60 is fabricated fro one of the above referenced conductive base materials 30; and the Luer adaptor 62 is made of a harder plastic, such as acrylic or polycarbonate. The sleeve 60 may be configured to accommodate a variety of catheter sizes. An adaptation of the composite material sleeve 60 ca also be configured as a catheter introducer sheath 66, show in Fig. 8, for inserting pulmonary artery (Swan-Ganz o thermodilution) catheters, temporary pacing leads, etc., which may remain in place for several weeks. Under norma circumstances, an introducer sheath is left in place with th catheter which it surrounds for a portion of its length, including the region where the device penetrates the skin. Iontophoretic introducer sheaths 66 are easily manufacture with the composite material approach because they ar predominantly made of polytetrafluorethylene (Teflon®) , viny (PVC) , or polyethylene (PE) , materials which can be loade with carbon or other conductive fillers or made conductiv by other means known in the art and then loaded as well a the first and second metal powders 32, 34. Fig. 8 shows the introducer sheath 66 used i conjunction with a thermodilution catheter 68. Balloon an - 13 - temperature sensing elements, 74 and 75 respectively, know to those skilled in the art, are shown on the distal end 20. Because the inside of the introducer sheath 66 is in intimat contact with the outer surface 16 of the elastomeric wall 12, the composite material 30, 32, 34 of the introducer sheat 66 protects both the sheath 66 and the outer wall 12 of th thermodilution catheter 68. Like the iontophoresis cathete 10, and the catheter 56 having an iontophoresis infectio control kit 58, the introducer sheath 66 is virtuall identical in size, shape, and use as prior art devices.

As described with respect to Figs. 1-8, variou embodiments of the composite material category of th iontophoretic structure for a medical device have bee illustrated. In composite material embodiments, the integral power source for driving oligodynamic metal ions int solution is the electromotive force created by dissimila metal powders 32, 34 embedded in and separated from eac other by the conductive base material 30 of specificall created resistivity. Referring now to Figs. 9-11, a variety of embodiment of the other category of iontophoretic structure for medical device are shown which incorporate the plurality o discrete layered structures. In these embodiments plurality of layered structures comprise dissimilar galvani materials separated by a resistive layer. These structure may be incorporated in the above-recited medical device during manufacture, or adhered to the surface of the device as an aftermarket item.

Referring to Fig. 9 a perspective view of an embodimen of an iontophoresis catheter 70 is shown, wherein th oligodynamic iontophoresis effect is achieved using plurality of layered structures 72 on either the inne surface 14, the outer surface 16, or both of a non-conductiv wall 12. The layered structures 72, while depicted in circular configuration can be any shape, such as oval o square. and thickness for the resistive layer 78 are possible t obtain the target current density.

Although the invention has been shown and described wit respect to exemplary embodiments thereof, various othe changes, omissions and additions in form and detail thereo may be made therein without departing from the spirit an scope of the invention.

- 20 -

23. An iontophoresis catheter comprising: an elastomeric cylindrical wall having an outer wall surface and an inner wall surface, said inner wall surface defining a lumen for containing an electrolytic fluid, and a distal end and a proximal end, each said end having at least one opening to permit introduction or evacuation of said electrolytic fluid from said lumen, said elastomeric cylindrical wall comprising a plurality of layered electrodes comprising a first metal layer, a second metal layer, and a resistive layer therebetween, said resistive layer having a predetermined resistance for controlling an electric current produced between said first metal layer and said second metal layer when said iontophoresis catheter is immersed in said electrolytic fluid to produce a desired current density that has an antibacterial effect.

24. An iontophoresis infection control kit for a catheter having a distal end, a proximal end, an inner lumen, and an outer surface, comprising: an infection control sleeve comprising a first metal powder and a second metal powder embedded in a conductive elastomeric material having a predetermined resistance for controlling a current flow produced between said first metal powder and said second metal powder when said infection control sleeve is in contact with an electrolytic solution to produce a desired current density that has an antibacterial effect, said sleeve placed over said outer surface of said catheter near said proximal end.

25. The iontophoresis infection control kit of claim 24, wherein said infection control sleeve is an introducer sheath.

26. The iontophoresis infection control kit of claim 25, further comprising an adaptor for securing said infection control sleeve in place over said outer surface and for

Claims

- 16 -

CLAIMS I claim:

1. An iontophoretic structure for a medical device, comprising: a first galvanic material having a first electrical potential; a second galvanic material having a second electrical potential; and a conductive material separating said first galvanic material from said first galvanic material, said conductive material having a predetermined resistance for controlling a current flow produced between said first galvanic material and said second galvanic material when said iontophoretic structure is in contact with an electrolytic fluid.

2. The iontophoretic structure of claim 1, wherein said first galvanic material comprises silver and said second galvanic material comprises gold.

3. The iontophoretic structure of claim 1, wherein said first galvanic material comprises silver and said second galvanic material comprises platinum.

4. The iontophoretic structure of claim 1, wherein said first galvanic material comprises silver and said second galvanic material comprises copper.

5. The iontophoretic structure of claim 1, wherein said conductive material is a conductive polymer.

6. The iontophoretic structure of claim 5, wherein said conductive polymer is chosen from the group consisting of polyvinyl, polyester, polyethylene, polyurethane and polyvinylidene. - 19 -

18. The iontophoresis catheter of claim 9, wherein said first galvanic material comprises a first metal layer, said second galvanic material comprises a second metal layer, and said first and said second layers have a resistive layer therebetween, said first and second metal layers and said resistive layer comprising an antibacterial structure.

19. The iontophoresis catheter of claim 18, wherein said lumen comprises a plurality of said antibacterial structures on said outer wall surface.

20. The iontophoresis catheter of claim 19, wherein said lumen comprises a plurality of said antibacterial structures on said inner wall surface.

21. The iontophoresis catheter of claim 18, wherein said lumen comprises a plurality of said antibacterial structures on said inner wall surface and said outer wall surface.

22. An iontophoresis catheter comprising: an elastomeric cylindrical wall having an outer wall surface and an inner wall surface, said inner wall surface defining a lumen for containing an electrolytic fluid, and a distal end and a proximal end, each said end having at least one opening to permit introduction or evacuation of said electrolytic fluid from said lumen, said elastomeric cylindrical wall comprising a first metal powder and a second metal powder embedded in a conductive material having a predetermined resistance for controlling a current flow produced between said first metal powder and said second metal powder when said iontophoresis catheter is contact with said electrolytic fluid to produce a desired current density that has an antibacterial effect. - 21 - connecting said proximal end of said catheter to intravenous tubing.

27. A method of providing antibacterial protection for an implantable medical device comprising: selecting a medical device having a surface that is exposed to bodily fluids when said medical device is implanted within a body; placing an iontophoretic structure on at least a portion of said surface, said iontophoretic structure including, a first plurality of metal particles having a first galvanic electrical potential, a second plurality of metal particles having a second galvanic electrical potential, and a non-conductive polymer loaded with a conductive material separating said first plurality of metal particles from said second plurality of metal particles, said conductive material providing said non-conductive polymer with a predetermined resistivity for controlling a current flow produced between said first plurality of metal particles and said second plurality of metal particles when said iontophoretic structure is in contact with an electrolytic fluid; and implanting said medical device within said body.

28. A method of providing antibacterial protection for an implantable medical device comprising: selecting a medical device having a surface that is exposed to bodily fluids when said medical device is implanted within a body; placing an iontophoretic structure on at least a portion of said surface, said iontophoretic structure including, a first metal layer having a first galvanic electrical potential, a second metal layer having a second galvanic electrical potential, and - 22 - a non-conductive polymer loaded with a conductive material separating said first metal layer from said second metal layer, said conductive material providing said non- conductive polymer with a predetermined resistivity for controlling a current flow produced between said first metal layer and said second metal layer when said iontophoretic structure is in contact with an electrolytic fluid; and implanting said medical device within said body.

29. A method of protecting a natural body structure with an iontophoretic structure including a first galvanic material having a first electrical potential, a second galvanic material having a second electrical potential, and a non- conductive polymer loaded with a conductive material separating said first galvanic material from said second galvanic material, said conductive material providing said non-conductive polymer with a predetermined resistivity for controlling a current flow produced between said first galvanic material and said second galvanic material when said iontophoretic structure is in contact with an electrolytic fluid, said first galvanic material including a first plurality of metal particles, said second galvanic material including a second plurality of metal particles, said first and said second plurality of metal particles embedded in said non-conductive polymer loaded with said conductive material, comprising the steps of: applying said iontophoretic structure in a pre-cured state to said natural body structure; and allowing said iontophoretic structure to cure.

30. The method of claim 29, wherein said non-conductive polymer loaded with a conductive material includes a binary adhesive.

31. The method of claim 29, wherein said body structure is a tooth. - 23 -

32. A method of providing antibacterial protection for an implantable medical device comprising: selecting a medical device having a surface that is exposed to bodily fluids when said medical device is implanted within a body; placing an iontophoretic structure on at least a portion of said surface, said iontophoretic structure including, a first plurality of metal particles having a first galvanic electrical potential, a second plurality of metal particles having a second galvanic electrical potential, and an inherently conductive polymer separating said first plurality of metal particles from said second plurality of metal particles, said inherently conductive polymer having a predetermined resistivity for controlling a current flow produced between said first plurality of metal particles and said second plurality of metal particles when said iontophoretic structure is in contact with an electrolytic fluid; and implanting said medical device within said body.

33. A method of protecting a natural body structure with an iontophoretic structure including a first galvanic material having a first electrical potential, a second galvanic material having a second electrical potential, and an inherently conductive polymer separating said first galvanic material from said second galvanic material, said inherently conductive polymer having a predetermined resistivity for controlling a current flow produced between said first galvanic material and said second galvanic material when said iontophoretic structure is in contact with an electrolytic fluid, said first galvanic material including a first plurality of metal particles, said second galvanic material including a second plurality of metal particles, said first - 24 - and said second plurality of metal particles embedded in said inherently conductive polymer, comprising the steps of: applying said iontophoretic structure in a pre-cured state to said natural body structure; and allowing said iontophoretic structure to cure.