COATINGS AND METHODS FOR CONTROLLED ELUTION OF HYDROPHILIC ACTIVE AGENTS
Embodiments of the invention include multi-layer coatings and methods for controlling the elution of hydrophilic active agents. In an embodiment, the invention includes a medical device including a substrate, a primer polymer layer disposed on the substrate, an expandable layer disposed on the primer polymer layer, and a hydrophilic active agent dispersed within the expandable layer. In an embodiment, the invention includes a method of forming a medical device including depositing a primer layer onto a substrate, the primer layer comprising a primer polymer. The method can further include depositing an expandable layer onto the primer layer, the expandable layer including an expandable polymer, and a hydrophilic active agent. The expandable layer can be deposited with a solvent that is effective to solvate both the expandable polymer and the primer polymer. Other embodiments are also included herein.
1 . A medical device comprising:
a substrate;
a primer polymer layer disposed on the substrate;
an expandable layer disposed on the primer polymer layer; and
a hydrophilic active agent dispersed within the expandable layer.
2 . The medical device of claim 1 , further comprising a top coat disposed on the expandable layer, the top coat comprising polyethylene-co-vinyl acetate (PEVA).
3 . The medical device of claim 2 , the polyethylene-co-vinyl acetate having a vinyl acetate concentration of between about 12 percent and 33 percent by weight.
4 . The medical device of claim 1 , the expandable layer configured to expand in volume at least about 5% after insertion into a subject.
5 . The medical device of claim 2 , the expandable layer comprising polyethylene-co-vinyl acetate (PEVA).
6 . The medical device of claim 5 , the polyethylene-co-vinyl acetate in the expandable layer having a vinyl acetate concentration of greater than or equal to about 33 percent by weight and less than or equal to about 40 percent by weight.
7 . The medical device of claim 1 , the expandable layer comprising at least one selected from the group consisting of cross-linked polysiloxane (silicone rubber) and butyl rubber.
8 . The medical device of claim 1 , the expandable layer comprising a hydrogel.
9 . The medical device of claim 1 , the expandable layer comprising poly lactide-co-glycolide (PLGA).
10 . The medical device of claim 1 , the expandable layer having a thickness of at least about 5 microns.
11 . The medical device of claim 1 , the primer layer configured to expand in volume less than about 5% after insertion into a subject.
12 . The medical device of claim 1 , the primer polymer layer comprising poly-n-butyl methacrylate (PBMA).
13 . The medical device of claim 1 , the primer polymer layer comprising polystyrene.
14 . The medical device of claim 1 , the primer polymer layer having a thickness of at least about 1 micron.
15 . The medical device of claim 1 , the hydrophilic active agent comprising at least one selected from the group consisting of a protein and a nucleic acid.
16 . The medical device of claim 1 , the expandable layer comprising at least trace amounts of a solvent effective to solvate the primer polymer layer disposed on the substrate.
17 . The medical device of claim 1 , the substrate comprising a portion of at least one selected from the group consisting of an eye coil, a stent, an electrical stimulation lead, and a bone screw.
18 . The medical device of claim 1 , the substrate selected from the group consisting of glasses, metals, and ceramics.
19 . A method of forming a medical device comprising:
depositing a primer layer onto a substrate, the primer layer comprising a primer polymer; and
depositing an expandable layer onto the primer layer, the expandable layer comprising
a expandable polymer, and
a hydrophilic active agent;
wherein the expandable layer is deposited with a solvent that is effective to solvate both the expandable polymer and the primer polymer.
20 . The method of claim 19 , further comprising depositing a top coat onto the expandable layer.