Stent Coating For Eluting Medication

• US 20100198335A1
• Filed: 04/07/2010
• Published: 08/05/2010
• Est. Priority Date: 01/28/2005
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Frysz, Christine A., O'Brien, Robert C.
• Granted Patent: US 8,367,151 B2
• Time in Patent Office: Days
• US Class Current: 623/1.15
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61F 2250/0068 the pharmaceutical product being in a reservoir
• CPC Class Codes: A61L 2300/108 Elemental carbon, e.g. charcoal
• CPC Class Codes: A61L 31/084 Carbon; Graphite
• CPC Class Codes: A61L 31/146 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 31/16 Biologically active materials, e.g. therapeutic substances A61L31/047 takes precedence
• CPC Class Codes: Y10T 29/49885 with coating before or during assembling

Abstract

A vascular stent comprising a drug-eluting outer layer of a porous sputtered columnar metal having each column capped with a biocompatible carbon-containing material is described. This is done by placing the stent over a close-fitting mandrel and rotating the assembly in a sputter flux. The result is a coating that is evenly distributed over the outward-facing side of the stent'"'"'s wire mesh while preventing the sputtered columnar coating from reaching the inward facing side where a smooth hemocompatible surface is required. The stent is then removed from the mandrel, exposing all surfaces, and finally coated with a layer of carbon such as amorphous carbon or diamond-like carbon. The carbonaceous coating enhances biocompatibility without preventing elutriation of a therapeutic drug provided in the porosity formed between the columnar structures. The result is a stent that is adapted to both the hemodynamic and the immune response requirements of its vascular environment.

Claims

1. A method for providing a stent suitable for insertion and expansion into a vasculature to support an adjacent vasculature region, comprising the steps of:

a) providing a plurality of wires forming an elongated and selectively expandable and constrictable hollow tube, each wire providing a substrate having a cross-section comprising an outside-facing surface portion and an inside-facing surface portion;

b) adhering an intermediate coating to the outside-facing surface portion of each substrate wire, the intermediate coating comprising a plurality of columnar structures having a sidewall extending between a proximal end adhered to the substrate wire and a distal end spaced therefrom, wherein the sidewalls of immediately adjacent columns do not contact each other to thereby provide porosity there between;

c) capping the distal end of each of the plurality of columnar structures with a carbon-containing material; and

d) filling an elutable material into the porosity provided between each of the plurality of columnar structures.

2. The method of claim 1 including expanding the stent to near an elastic stress limit of the plurality of wires prior to providing the intermediate coating thereon.

3. The method of claim 1 including providing the stent comprising a nickel titanium shape memory alloy heated to near an elastic stress limit of the plurality of wires prior to providing the intermediate coating thereon.

4. The method of claim 1 including heating the nickel titanium shape memory alloy to near its elastic stress limit in a sputter chamber.

5. The method of claim 1 including providing the an elutable material as a medication filled into the porosity between the columnar structures and comprising a polymer selected from the group consisting of polyurethane, silicone, polyesters, polycarbonate, polyethylene, polyvinyl chloride, polypropylene methylacrylate, para-xylylene, and mixtures thereof.

6. The method of claim 1 including providing a polymeric material covering the carbonaceous caps.

7. The method of claim 1 including adhering the intermediate coating to the substrate and capping the distal end of each of the plurality of columnar structures with the carbon-containing coating by one of the deposition techniques selected from the group consisting of sputtering, chemical vapor deposition, pulsed laser deposition, reactive evaporation, and as a thermal spray.

8. A method for providing a stent suitable for insertion and expansion into a vasculature to support an adjacent vasculature region, comprising the steps of:

a) providing a plurality of wires comprising a shape memory alloy forming an elongated and selectively expandable and constrictable hollow tube, each wire providing a substrate having a cross-section comprising an outside-facing surface portion and an inside-facing surface portion;

b) heating the shape memory alloy to near its elastic stress limit;

c) adhering an intermediate coating on the outside-facing surface portion of each substrate wire, the intermediate coating comprising a plurality of columnar structures having a sidewall extending between a proximal end adhered to the substrate wire and a distal end spaced therefrom, wherein the sidewalls of immediately adjacent columns do not contact each other to thereby provide porosity there between;

d) capping the distal end of each of the plurality of columnar structures with a carbon-containing material formed thereon; and

e) filling an elutable material into the porosity provided between each of the plurality of columnar structures.

9. The method of claim 8 including providing the stent comprising a nickel titanium shaped memory alloy.