Barriers for polymer-coated implantable medical devices and methods for making the same

• US 6,953,560 B1
• Filed: 10/03/2003
• Issued: 10/11/2005
• Est. Priority Date: 09/28/2000
• Status: Expired due to Fees

• Current Assignee: Advanced Cardiovascular Systems Incorporated (Abbott Laboratories)
• Original Assignee: Advanced Cardiovascular Systems Incorporated (Abbott Laboratories)
• Inventors: Castro, Daniel, Pacetti, Stephen D.
• Primary Examiner(s): Azpuru, Carlos A.
• Application Number:
  US10/678,346
• Time in Patent Office: 739 Days
• Field of Search: 424/423, 623/1.1, 623/1.15, 623/1.23
• US Class Current: 423/423
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2/86 Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61F 2310/0097 Coating or prosthesis-covering structure made of pharmaceutical products, e.g. antibiotics
• CPC Class Codes: A61L 2300/416 Anti-neoplastic or anti-proliferative or anti-restenosis or anti-angiogenic agents, e.g. paclitaxel, sirolimus
• CPC Class Codes: A61L 2300/602 Type of release, e.g. controlled, sustained, slow
• CPC Class Codes: A61L 2300/606 Coatings
• CPC Class Codes: A61L 2420/08 Coatings comprising two or more layers
• CPC Class Codes: A61L 27/306 Other specific inorganic materials not covered by A61L27/303 - A61L27/32
• CPC Class Codes: A61L 27/34 Macromolecular materials
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 31/088 Other specific inorganic materials not covered by A61L31/084 or A61L31/086
• CPC Class Codes: A61L 31/10 Macromolecular materials
• CPC Class Codes: A61L 31/16 Biologically active materials, e.g. therapeutic substances A61L31/047 takes precedence
• CPC Class Codes: C08L 31/04 Homopolymers or copolymers of vinyl acetate
• CPC Class Codes: C08L 33/10 Homopolymers or copolymers of methacrylic acid esters

Abstract

An implantable medical device and methods for making the implantable medical device are disclosed. The implantable medical device includes a substrate. At least a portion of the substrate is coated with a first layer including a polymer containing a drug. A barrier overlies the first layer. The barrier significantly reduces the rate of release of the drug from the polymer, thereby sustaining release of the drug from the medical device for a longer time.

The barrier may be a homogeneous layer overlying the first layer, or a number of discrete deposits over the first layer. Alternatively, the barrier may be intermixed with an outer portion of the first layer. The barrier material is biocompatible, and typically has a thickness ranging from about 50 angstroms to about 20,000 microns. Suitable materials for the barrier include, but are not limited to, inorganic compounds, such as inorganic silicides, oxides, nitrides, carbides, as well as pure metals such as aluminum, chromium, gold, hafnium, iridium, niobium, palladium, platinum, tantalum, titanium, tungsten, zirconium, and alloys of these metals. The barriers disclosed may be applied to the first layer by several techniques, depending on the material being applied. Exemplary deposition techniques include physical vapor deposition, alkoxide hydrolysis, and electroless plating.

The implantable device may be a stent or a graft, among other possibilities.

Claims

1. An implantable medical device comprising:

a substrate;

a polymeric coating including a therapeutic agent supported by the substrate, wherein the polymeric coating includes a mixture of poly(butyl methacrylate) and poly(ethylene co-vinyl acetate) and the therapeutic agent includes rapamycin; and

a barrier layer over at least a portion of the polymeric coating, wherein the barrier reduces the rate of release of rapamycin.

2. The implantable medical device of claim 1, wherein the barrier layer is biodegradable.

3. The implantable medical device of claim 1, wherein the therapeutic agent has a lower diffusivity in the barrier layer than in the polymeric coating.

4. The implantable medical device of claim 1, wherein the barrier layer is a homogeneous layer.

5. The implantable medical device of claim 1, wherein the device is a stent.