Coatings Comprising Self-Assembled Molecular Structures

Abstract

A coating for an implantable medical device is disclosed, the coating including a self-assembled molecular structure. The coating can be used for altering the release rate of a therapeutic substance from the implantable device.

1 . A coating for an implantable medical device comprising:
 a drug;   a polymer layer having a crystalline structure, wherein the structure of the polymer becomes less crystalline when the polymer is exposed to a electric signal, and wherein when the electric signal is terminated, the structure of the polymer returns back to essentially the same degree of crystallinity or a more crystalline structure than that of when the polymer was exposed to the electric signal.   
   
   
       2 . The coating of  claim 1 , wherein the coating further comprises a drug reservoir layer comprising the drug. 
   
   
       3 . The coating of  claim 1 , wherein drug reservoir layer further comprises a polymer. 
   
   
       4 . The coating of  claim 3 , wherein the polymer layer is chemically bonded to the drug reservoir layer. 
   
   
       5 . The coating of  claim 3 , wherein the polymer of the reservoir layer includes at least one reactive functional group. 
   
   
       6 . The coating of  claim 3 , wherein the reactive functional group is selected from the group consisting of hydroxyl, carboxyl, amino, and thiol. 
   
   
       7 . The coating of  claim 3 , wherein the polymer of the reservoir layer is selected from the group consisting of poly(ethylene-co-vinyl alcohol), poly(butyl methacrylate-co-2-hydroxyethyl methacrylate), poly(2-hydroxyethyl methacrylate), and poly(amino acid). 
   
   
       8 . The coating of  claim 3 , wherein the drug comprises anti-inflammatory corticoids. 
   
   
       9 . The coating of  claim 8 , where the drug is selected from the group consisting of dexamethasone acetate, dexamethasone sodium phosphate and mixtures thereof. 
   
   
       10 . The coating of  claim 1 , wherein the compound of the polymer layer comprises at least one reactive functional group. 
   
   
       11 . The coating of  claim 10 , wherein the reactive functional group is selected from the group consisting of hydroxyl, carboxyl, sulfonyl, isocyanate, epoxy, amino, thiol, and acrylic. 
   
   
       12 . The coating of  claim 1 , wherein the polymer layer comprises a compound of the following formula: R-A-R′, wherein each of R and R′ is independently a hydrogen, methyl, hydroxyl, carboxyl, sulfonyl, acetate, trifluoro acetate, benzoate, isocyanate, epoxy, amino, thiol, or acrylic group and A is a methylene or a silicone chain. 
   
   
       13 . The coating of  claim 1 , the polymer layer comprises a compound of the following formula: R-A-R′, wherein at least one of R or R′ is a reactive group, and A is a methylene or silicone chain. 
   
   
       14 . The coating of  claim 1 , wherein the polymer layer comprises a compound of the following formula: R-A-R′, wherein at least one of R or R′ is an isocyanate, epoxy or hydroxyl group, and A is a silicone chain or a methylene chain. 
   
   
       15 . The coating of  claim 1 , wherein the polymer layer comprises a hydroxyl-terminated compound. 
   
   
       16 . The coating of  claim 1 , wherein the polymer layer comprises an isocyanate-terminated compound. 
   
   
       17 . The coating of  claim 1 , wherein the polymer layer comprises a carboxyl-terminated compound. 
   
   
       18 . A coating for an implantable medical device comprising:
 a reservoir layer comprising a polymer and a drug;   a second layer applied over the reservoir layer, the second layer comprising a self-assembled structure of molecules of an organic or elemento-organic substance having a crystalline structure, wherein the structure of the organic or elemento-organic substance becomes less crystalline and more amorphous when the organic or elemento-organic substance is exposed to an electric signal, and wherein when the electric signal is terminated, the structure of the organic or elemento-organic substance returns back to essentially the same degree of crystallinity or a more crystalline structure than the structure before exposure to the electric signal.