Implantable Neuro-Stimulation Electrode with Drug Elution Material

Abstract

An implantable electrode with a fluid reservoir is described. An implantable electrode carrier has an outer surface including electrode contacts for electrically stimulating nearby neural tissue. A fluid reservoir within the electrode carrier stores a volume of therapeutic fluid. At least one fluid delivery port connects the fluid reservoir to the outer surface of the electrode carrier for delivering the therapeutic fluid from the fluid reservoir to the outer surface. A delivery septum port is in fluid communication with the fluid reservoir for delivering the therapeutic fluid to the fluid reservoir.

1 . A cochlear implant electrode array comprising: 
 a cochlear electrode array for electrically stimulating cochlear tissue, the array including a drug eluting portion having a pharmaceutical agent incorporated into a polymer material,    wherein the drug eluting portion is adapted to release over time a therapeutically effective amount of the pharmaceutical agent for the inner ear.    
   
   
       2 . An electrode array according to  claim 1 , wherein the electrode array includes a slot containing the polymer material.  
   
   
       3 . An electrode array according to  claim 2 , wherein the geometry of the slot determines the rate at which the pharmaceutical agent is released.  
   
   
       4 . An electrode array according to  claim 1 , wherein the pharmaceutical agent is a gel or powder incorporated into the polymer material.  
   
   
       5 . An electrode array according to  claim 1 , wherein the polymer material is a silicon-based elastomer.  
   
   
       6 . An electrode array according to  claim 1 , wherein the drug eluting portion is a layer of polymer material sandwiched between two layers of non-drug eluting material.  
   
   
       7 . An electrode array according to  claim 1 , wherein the drug eluting portion comprises 1% to 2% of the mass of the electrode array.  
   
   
       8 . An electrode array according to  claim 1 , wherein the drug eluting portion is embedded within non-drug eluting material.  
   
   
       9 . An electrode array according to  claim 8 , wherein the thickness of the non-drug eluting material determines the rate at which the pharmaceutical agent is released.  
   
   
       10 . An electrode array according to  claim 1 , wherein the drug eluting portion begins at 3 mm or more from where the electrode array enters the inner ear.  
   
   
       11 . An electrode array according to  claim 1 , wherein the release rate of the pharmaceutical agent is based on cross-linked density of the polymer material in the drug eluting portion.  
   
   
       12 . An electrode array according to  claim 1 , wherein the release rate of the pharmaceutical agent is based on the amount of surface area of the drug eluting portion which is exposed to the fluid of the inner ear.  
   
   
       13 . An electrode array according to  claim 1 , wherein the release rate of the pharmaceutical agent is based on the volume of the drug eluting portion.  
   
   
       14 . An electrode array according to  claim 1 , wherein the drug eluting portion includes first and second drug eluting portions, each portion adapted to release a different pharmaceutical agent.  
   
   
       15 . An electrode array according to  claim 1 , wherein the electrode array includes a plurality of electrical contacts for electrically stimulating the cochlear tissue, at least one of the contacts being coated with the pharmaceutical agent.  
   
   
       16 . An electrode array according to  claim 1 , wherein the pharmaceutical agent is in the form of solid particles of less than 200 μm mixed into the material of the drug eluting portion.  
   
   
       17 . An electrode array according to  claim 1 , wherein the release rate of the pharmaceutical agent is based on having particles of the pharmaceutical agent in a plurality of defined sizes.  
   
   
       18 . An electrode array according to  claim 17 , wherein at least 90% of the particles are less than 200 μm.  
   
   
       19 . An electrode array according to  claim 17 , wherein at least 50% of the particles are less than 50 μm.  
   
   
       20 . An electrode array according to  claim 1 , wherein the pharmaceutical agent is a corticosteroid.  
   
   
       21 . An electrode array according to  claim 20 , wherein the corticosteroid includes betamethasone, clobethasole, diflorasone, fluocinonide, triamcilione, or a salt or combination thereof.  
   
   
       22 . An electrode array according to  claim 21 , wherein the corticosteroid is dexamethasone.  
   
   
       23 . An electrode array according to  claim 2 , wherein the electrode array is adapted to release between 5 mg and 600 mg of dexamethasone during an initial 24 hour period of use.  
   
   
       24 . An electrode array according to  claim 1 , wherein the pharmaceutical agent is an anti-inflammatory agent.  
   
   
       25 . An electrode array according to  claim 1 , wherein the pharmaceutical agent is a bactericide.