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Coatings for medical devices comprising a therapeutic agent and a metallic material

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Coatings for medical devices comprising a therapeutic agent and a metallic material


The invention relates generally to an implantable medical device for delivering a therapeutic agent to the body tissue of a patient, and a method for making such a medical device. In particular, the invention pertains to an implantable medical device, such as an intravascular stent, having a coating comprising a first coating composition comprising a therapeutic agent and, optionally, a polymer; and a second coating composition comprising a metallic material.

Browse recent Boston Scientific Scimed, Inc. patents - Maple Grove, MN, US
Inventor: Pu Zhou
USPTO Applicaton #: #20120323308 - Class: 623 116 (USPTO) - 12/20/12 - Class 623 
Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor > Arterial Prosthesis (i.e., Blood Vessel) >Stent Structure >Having Multiple Connected Bodies



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The Patent Description & Claims data below is from USPTO Patent Application 20120323308, Coatings for medical devices comprising a therapeutic agent and a metallic material.

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FIELD OF THE INVENTION

The invention relates generally to implantable medical devices for delivering a therapeutic agent to the body tissue of a patient, and methods for making such medical devices. In particular, the invention pertains to implantable medical devices, such as intravascular stents, having a coating comprising a first coating composition comprising a therapeutic agent and a second coating composition comprising a metallic material.

BACKGROUND OF THE INVENTION

Medical devices have been used to deliver therapeutic agents locally to the body tissue of a patient. For example, intravascular stents comprising a therapeutic agent have been used to locally deliver therapeutic agents to a blood vessel. Often such therapeutic agents have been used to prevent restenosis. Examples of stents comprising a therapeutic agent include stents that comprise a coating containing a therapeutic agent for delivery to a blood vessel. Studies have shown that stents having a coating with a therapeutic agent are effective in treating or preventing restenosis.

Even though medical devices having a coating with a therapeutic agent are effective in preventing restenosis, many coated medical devices, in addition to being coated with a therapeutic agent, are also coated with a polymer. The benefits of using a polymer in such coatings include easier loading of therapeutic agents onto the surface of a medical device and the ability to control or regulate the rate of release of the therapeutic agent.

However, the use of polymers in medical device coatings can also have some disadvantages. For example, depending on the type of polymer used to coat the medical device, some polymers can cause inflammation of the body lumen, offsetting the effects of the therapeutic agent. Additionally, some polymers may also cause thrombosis.

Accordingly, there is a need for coatings for a medical device that prevent or at least reduce the disadvantages associated with polymer coatings, such as inflammation caused by contact with the body lumen. Moreover, there is a need for a coating for medical devices that can control or regulate the release rate of a therapeutic agent without the use of polymer coatings. There is also a need for methods of making such medical devices.

SUMMARY

OF THE INVENTION

These and other objectives are accomplished by the present invention. The present invention provides a medical device, such as an implantable, intravascular stent comprising a coating. The coating is designed to eliminate or at least reduce the amount of polymer contact with the body tissue, such as a body lumen, while still providing a suitable release rate of the therapeutic agent. The coating comprises a first coating composition comprising a therapeutic agent and a second coating composition comprising a metallic material. Optionally, the first coating composition can further comprise a polymer.

The coating can comprise a first coating composition comprising a therapeutic agent, disposed on the surface of a medical device; and a second coating composition, which comprises a metallic material and which is substantially free of any polymer, disposed on at least a portion of the first coating composition. Metallic materials are materials containing a metal including but not limited to, metals alloys and oxides. As used herein and unless otherwise defined the phrase “substantially free of any polymer” means having less than or equal to 50% of polymer by volume of the composition. With such coatings, polymer contact with the body lumen is reduced or eliminated.

For example, the present invention is directed to an implantable intravascular stent comprising: (a) a stent sidewall structure having a surface; and (b) a coating comprising: (i) a first coating composition comprising a therapeutic agent disposed upon at least a portion of the surface of the stent sidewall structure, wherein the first coating composition, when disposed on the portion of the surface of the stent sidewall structure, has an outer surface; and (ii) a second coating composition comprising a metallic material disposed on at least a portion of the first coating composition, wherein the second coating composition is substantially free of any polymer when applied to the portion of the first coating composition; and wherein after the second coating composition is applied to the portion of the first coating composition the second coating composition comprises an outer surface and a plurality of pores, in which the pores extend from the outer surface of the first coating composition to the outer surface of the second coating composition. In certain embodiments of the present invention the second coating composition is disposed on less than the entire outer surface of the first coating composition. Additionally, the second coating composition can also be further disposed on a portion of the surface of the stent sidewall structure.

The stent sidewall structure can be an abluminal surface or an adluminal surface. In certain embodiments, the coating is disposed on at least a portion of the abluminal surface. In other embodiments, the first coating composition is disposed on at least a portion of the abluminal surface and the second coating composition is disposed on at least a portion of the first coating composition disposed on the adluminal surface. In still other embodiments, the first coating composition is disposed on at least a portion of the abluminal surface and the adluminal surface is free of the second coating composition.

Additionally, the stent sidewall structure can comprise a plurality of struts wherein the surface of the stent sidewall structure is the abluminal surface or adluminal surface of at least one of the struts. When the stent sidewall structure comprises a plurality of struts, the coating can be disposed on at least a portion of the abluminal or adluminal surface of at least one of the struts. For example, the present invention is directed to an implantable intravascular stent comprising: (a) a stent sidewall structure comprising a plurality of struts each having an abluminal surface and an adluminal surface (b) a first coating disposed on the abluminal surface of at least one strut comprising: (i) a first coating composition comprising as anti-restenosis agent disposed upon at least a portion of the abluminal surface of the strut, wherein the first coating composition, when disposed on the portion of the surface of the abluminal surface of the strut has an outer surface; and (ii) a second coating composition comprising a metallic material disposed on at least a portion of the first coating composition, wherein the second coating composition is substantially free of any polymer; and wherein after the second coating composition is applied to the portion of the first coating composition the second coating composition comprises an outer surface and a plurality of pores, in which the pores extend from the outer surface of the first coating composition to the outer surface of the second coating composition; and (c) a second coating disposed on at least a portion of the adluminal surface of the at least one strut comprising the first coating composition.

In certain embodiments, the first coating composition is disposed on at least a portion of the adluminal surface of at least one of the struts and at least a portion of the adluminal surface of at least one of the struts is free of the second coating composition. In other embodiments, the first coating composition is disposed on at least a portion of the adluminal surface of at least one of the struts and the second coating composition is disposed on at least a portion of the first coating composition that is disposed on the adluminal surface.

In certain embodiments, the stent sidewall structure can further comprise a plurality of openings therein. When the stent sidewall structure has a plurality of openings, the first and second coating compositions can conform to the stent sidewall structure to preserve the openings in the stent sidewall structure. For example the present invention includes an implantable intravascular stent comprising: (a) a stent sidewall structure comprising (1) a plurality of struts each having an abluminal surface and an adluminal surface, and (2) openings in the stent sidewall structure; (b) a first coating disposed on the abluminal surface of at least one strut comprising: (i) a first coating composition comprising an anti-restenosis agent disposed upon at least a portion of the abluminal surface of the strut, wherein the first coating composition, when disposed on the portion of the surface of the abluminal surface of the strut, has an outer surface; and (ii) a second coating composition comprising a metallic material disposed on at least a portion of the first coating composition, wherein the second coating composition is substantially free of any polymer; and wherein after the second coating composition is applied to the portion of the first coating composition, the second coating composition comprises an outer surface and a plurality of pores, in which the pores extend from the outer surface of the first coating composition to the outer surface of the second coating composition; and (c) a second coating disposed on at least a portion of the adluminal surface of the at least one strut comprising the first coating composition, wherein the adluminal surface of the at least one strut is free of the second coating composition; and wherein the first and second coatings conform to the stent sidewall structure to preserve the openings therein.

Also the present invention is directed to an implantable intravascular stent comprising: (a) a stent sidewall structure having a surface; and (b) a coating comprising (i) a first coating composition comprising a therapeutic agent disposed upon at least a portion of the surface of the stent sidewall structure wherein the first coating composition has a first thickness; and (ii) a second coating composition comprising a metallic material disposed upon at least a portion of the surface of the stent sidewall structure, wherein the second coating composition has a second thickness and is substantially free of any polymer; and wherein the first thickness of the first coating composition is not greater than the second thickness of the second coating composition. The first coating composition can also further comprise a polymer.

In certain embodiments, the second thickness of the second coating composition can be greater than the first thickness of the first coating composition. Alternatively, the first thickness of the first coating composition can be equal to the second thickness of the second coating composition. Moreover, the second coating composition can be disposed adjacent to the first coating composition on the surface of the stent side wall structure.

In any of the embodiments described above, the first thickness of the first coating composition can be about 1 micron to about 30 microns and the second thickness of the second coating composition can be about 0.1 microns to about 50 microns.

The therapeutic agent in the first coating composition can comprise an agent that inhibits smooth muscle cell proliferation. The therapeutic agent in the first coating composition can also comprise an anti-thrombogenic agent, anti-angiogenesis agent, anti-proliferative agent, antibiotic, anti-restenosis agent, growth factor, immunosuppressant or radiochemical. For example the therapeutic agent can comprise paclitaxel, sirolimus, tacrolimus, pimecrolimus, everolimus or zotarolimus.

Additionally, the first coating composition further comprises at least one polymer. Suitable polymers include, but are not limited to, styrene-isobutylene copolymers, polylactic acid and poly(methylmethacrylate-butyl acrylate-methyl methacrylate).

The metallic material of the second coating composition can be selected from the group consisting of stainless steel, nickel, titanium, chromium and alloys thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be explained with reference to the following drawings.

FIG. 1 shows a cross-sectional view of an embodiment of a coating disposed on at least a portion of a medical device.

FIG. 2 shows a cross-sectional view of another embodiment of a coating disposed on at least a portion of a medical device.

FIG. 3 shows a portion of a medical device that is suitable for use in the present invention.

FIG. 4 shows a cross-sectional view of a stent.

FIG. 4a shows a cross-sectional view of a strut of a stent having a coating thereon.

FIG. 4b shows a cross-sectional view of another embodiment of a strut of a stent having a coating thereon.

FIG. 5 shows a perspective view of an embodiment of a coating disposed on at least a portion of a stent.

FIG. 6 shows a perspective view of another embodiment of a coating disposed on at least a portion of a stent.

FIG. 7 shows a perspective view of yet another embodiment of a coating disposed on at least a portion of a stent.

FIG. 8 shows a perspective view of yet another embodiment of a coating disposed on at least a portion of a stent.

FIG. 9 shows a cross-sectional view of another embodiment of a coating disposed on at least a portion of a medical device.

FIG. 10 shows a cross-sectional view of yet another embodiment of a coating disposed on at least a portion of a medical device.

FIG. 11 shows a cross-sectional view of yet another embodiment of a coating disposed on at least a portion of a medical device.

DETAILED DESCRIPTION

The present invention is directed to a medical device comprising a coating comprising a first coating composition containing a therapeutic agent and optionally a polymer. The medical device also includes a second coating composition containing a metallic material and is substantially free of any polymer.

In certain embodiments, the coating comprises a first coating composition comprising a therapeutic agent disposed on the surface of the medical device and a second coating composition comprising a metallic material disposed on the first coating composition. The second coating composition is substantially free of any polymer. Also, after the second coating composition is disposed on the first coating composition, wherein the second coating composition comprises a plurality of pores that extend from the outer surface of the first composition to the outer surface of the second coating composition.

FIG. 1 shows a cross-sectional view an embodiment of a coating disposed on at least a portion of a medical device such as a stent. In this embodiment, medical device 10 has a surface 12 and a coating 20. Coating 20 includes a first coating composition 22 comprising a therapeutic agent 30 disposed on at least a portion of the surface 12 of the medical device 10. When disposed on the surface 12, the first coating composition 22 has an outer surface 22a. The coating also includes a second coating composition 24 disposed on at least a portion of the first coating composition 22. The second coating composition 24 comprises a metallic material and is substantially free of any polymer. The second coating composition 24 can be disposed on a portion of or the entire first coating composition 22.

As shown in FIG. 1, the second coating composition 24 after being applied to the first coating composition 22 has an outer surface 24a and also has a plurality of pores 42. At least some of the pores 42 extend from the outer surface 22a of the first coating composition 22 to the outer surface 24a of the second coating composition 24. The pores 42 can be partially or completely filled with the first coating composition 22. In either case having the pores that extend from the outer surface 22a of the first coating composition 22 to the outer surface 24a of the second coating composition 24 allows the therapeutic agent 30 to be released from the first coating composition 22 underlying the second coating composition 24. Additionally, having pores 42 that allow for fluid communication between the outer surfaces 22a and 24a can aid in vascularization, provide long term non-inflammation and minimize or eliminate thrombosis. Furthermore, some or all of the pores 42 in the second coating composition 24 can be interconnected to other pores 42 within the second coating composition 24. In some embodiments, the pores 42 may be disposed in a desired pattern.

In addition, the pores 42 in the second coating composition 24 may have any shape. For example, the pores 42 can be shaped like channels, void pathways or microscopic conduits, spheres or hemispheres. Additionally, the pores 42 in the second coating composition 24 may have any size or range of sizes. In some instances, the pores 42 can be micropores or nanopores. Also, in some embodiments, it may be preferable that the width or diameter of the pores 42 is between about 1 nm and about 10 μm.

The size of the pores 42 can also be used to control the release rate of the therapeutic agent 30. For example, pores 42 having a larger width will allow the therapeutic agent 30 to be released more quickly than pores 42 with a smaller width. Also, the number of pores 42 in the second coating composition 24 can be adjusted to better control the release rate of the therapeutic agent 30. For example, the presence of more pores 42 per unit volume or weight of the second coating composition 24 can allow for a higher release rate of the therapeutic agent 30 than a material having fewer pores 42 therein.

In other embodiments, the coating comprises a first coating composition comprising a therapeutic agent and a polymer disposed on the surface of a medical device and a second coating composition comprising a metallic material disposed on the first coating composition. The second coating composition is substantially free of any polymer. Also, the after the second coating composition is disposed on the first coating composition, the second coating composition comprises a plurality of pores that extend from the outer surface of the first composition to the outer surface of the second coating composition.

FIG. 2 shows a cross-sectional view of another embodiment of a coating disposed on at least a portion of a surface of a medical device. In this embodiment medical device 10 has a surface 12 and a coating 20. Coating 20 has a first coating composition 22 comprising a therapeutic agent 30 and a polymer 32 disposed on the surface 12 of the medical device 10. The first coating composition 21 when disposed on the surface 12 has an outer surface 22a. A second coating composition 24 comprising a metallic material 40 is disposed on at least a portion of the first coating composition 22. As shown in FIG. 2, the second coating composition 24, when applied on the first coating composition 22, has an outer surface 24a and a plurality of pores 42. Like FIG. 1, the pores 42 extend from the outer surface 22a of the first coating composition 22 to the outer surface 24a of the second coating composition 24.

As shown in FIGS. 1 and 2, the first and second coating compositions can be disposed on the surface of a medical device in the form of layers. The coating can comprise one layer of each of the first and second coating compositions, as shown in FIGS. 1 and 2. However, more than one layer of each of the first and second coating compositions can be disposed on the surface of a medical device.

In other embodiments, the first coating composition disposed on the surface of medical device in a layer can have a thickness of about 1 micron to about 30 microns or about 1 micron to about 10 microns. Preferably, the first coating composition can have a thickness of about 3 microns to about 15 microns or about 0.8 microns to about 3.5 microns. In some instances, a relatively thicker layer may be preferred to incorporate greater amounts of the therapeutic agent. In addition, a relatively thicker layer may allow a greater amount of a therapeutic agent to be released over time.

The second coating composition comprising a metallic material, when disposed on the first coating composition, can have a thickness of about 0.1 micron to about 30 microns. Preferably, the second coating composition comprising a metallic material, when disposed on the first coating composition, can have a thickness of about 1 micron to about 10 microns. In addition, a relatively thicker film may allow the therapeutic agent to be released more slowly over time.

For the second coating composition, suitable metallic materials include any material that includes a metal such as, but not limited to metals, metal alloys or metal oxides that are biocompatible. Such metallic materials include, but are not limited to, metals and alloys based on titanium (such as nitinol, nickel titanium alloys, thermo-memory alloy materials); stainless steel; tantalum; tungsten; molybdenum; nickel-chrome; or certain cobalt alloys including cobalt-chromium-nickel alloys such as Elgiloy® and Phynox®; PERSS (Platinum EnRiched Stainless Steel) and Niobium. Metallic materials also include clad composite filaments, such as those disclosed in WO 94/16646. Preferred, metallic materials include, platinum enriched stainless steel and zirconium and niobium alloys. Additionally, combinations of more than one metal or alloy can be used in the coatings of the present invention.

In some embodiments, the metallic material comprises at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, at least 99% or more by weight of the second coating composition. Preferably, the metallic material is about 1% to about 80% by weight of the first coating composition. More preferably, the metallic material is about 50% to about 100% by weight of the second coating composition.

The second coating composition is substantially free of any polymer, i.e. contains less than about 50% of polymer by weight of the second coating composition. In some embodiments, the second coating composition is free of any polymer.

The coating can be disposed on the entire surface of the medical device or the coating can be disposed on a portion of the medical device. For example, if a medical device, such as a stent, that has an abluminal surface, i.e. the surface that contacts the body tissue, and an adluminal surface i.e. the surface that faces the lumen of the stent and is opposite the abluminal surface, the coating can be disposed on the abluminal surface while the adluminal surface can be free of the coating.

FIG. 3 shows an example of a portion of a stent that is suitable for use in the present invention that has an abluminal and adluminal surface. FIG. 3 shows an implantable intravascular stent 50 comprising a sidewall 52, which comprises a plurality of struts 60 and openings 55 in the sidewall 52. Generally, the openings 55 are disposed between adjacent struts 60. Also, the sidewall 52 may have a first sidewall surface 56 and an opposing second sidewall surface, which is not shown in FIG. 3. The first sidewall surface 56 can be an abluminal surface or outer sidewall surface, which faces the body tissue when the stent is implanted, or an adluminal surface or inner sidewall surface, which faces away from the body tissue. Likewise, the second sidewall surface can be an abluminal surface or an adluminal surface.

In certain embodiments, when the medical device, such as a stent, has a sidewall structure with openings therein it is preferable that the first coating composition and second coating composition disposed on the surface medical device, conform to the sidewall structure of the medical device so that the openings in the sidewall structure are preserved, e.g. the openings are not entirely or partially occluded with coating material.

FIG. 4 shows a cross-sectional view of an intravascular stent 100 that comprises a plurality of struts 105 and a lumen 130. The struts 105 each comprise an abluminal surface 110, which faces away from the lumen 130, and contact the body tissue, such as a blood vessel, when the stent 100 is implanted. The struts 105 each comprise an adluminal surface 120, which faces the lumen 130 when the stent 100 is implanted.

FIGS. 4a and 4b show two embodiments where the struts of the stent 100 of FIG. 4 include the coatings of the present invention. In particular, FIG. 4a shows an embodiment where the first coating composition 22 is disposed on at least a portion of the abluminal surface 12a and the adluminal surface 12b of a strut 105. The first coating composition 22 comprises a therapeutic agent 30 and optionally a polymer. A second coating composition 24 comprising a metallic material 40 is disposed on at least a portion of the first coating composition 22 that is disposed on the abluminal surface 12a and the adluminal surface 12b of the strut 105. The second coating composition 24 when applied on the first coating composition 22 has an outer surface 24a and a plurality of pores 42. The pores 42 extend from the outer surface 22a of the first coating composition 22 to the outer surface 24a of the second coating composition 24.

FIG. 4b shows an embodiment where the first coating composition 22 is disposed on at least a portion of the abluminal surface 12a and the adluminal surface 12b of a strut 105. The first coating composition 22 comprises a therapeutic agent 30 and optionally a polymer. A second coating composition 24 comprising a metallic material 40 is disposed only on at least a portion of the first coating composition 22 that is disposed on the abluminal surface 12a. The second coating composition 24 is not disposed on the portion of the first coating composition 22 that is disposed on the adluminal surface 12b of the strut 105. Like FIG. 4a, the second coating composition 24 when applied on the first coating composition 22 has an outer surface 24a and a plurality of pores 42. The pores 42 extend from the outer surface 22a of the first coating composition 22 to the outer surface 24a of the second coating composition 24.

The second coating composition can be disposed completely over the first coating composition or the second coating composition can be disposed over a portion of the first coating composition. Additionally the second coating composition can be disposed on the first coating composition in any configuration such as, rings, bands, stripes or dots.

FIG. 5 shows a perspective view of a round stent strut 200 comprising a surface 205 and a coating 210. Coating 210 is disposed on surface 205. Coating 210 comprises a first coating composition 215 comprising a therapeutic agent 220 and a polymer 225 disposed on surface 205 and a second coating composition 230 comprising a metallic material 240 disposed on the first coating composition 215. In this embodiment, the second coating composition 230 is disposed on the first coating composition 215 in the configuration of rings 250.

FIG. 6 shows a perspective view of a square-shaped stent strut 300 comprising a surface 305 and a coating 310. Coating 310 is disposed on surface 305. Coating 310 comprises a first coating composition 315 comprising a therapeutic agent 320 and a polymer 325 disposed on surface 305 and a second coating composition 330 comprising a metallic material 340 with pores as discussed above, disposed on the first coating composition 315. In this embodiment, the second coating composition 330 is disposed on the first coating composition 315 in the configuration of bands 350.

In another embodiment, second coating composition can be in the configuration of parallel bands or stripes. FIG. 7 shows a stent strut 400 comprising a surface 405 and a coating 410. Coating 410 is disposed on surface 405. Coating 410 comprises a first coating composition 415 comprising a therapeutic agent 420 and a polymer 425 disposed on surface 405 and a second coating composition 430 comprising a metallic material 440 with pores as discussed above, disposed on the first coating composition 415. In this embodiment, the second coating composition 430 is disposed on the first coating composition 415 in the configuration of parallel bands or stripes 450.

FIG. 8 shows a stent strut 500 comprising a surface 505 and a coating 510. Coating 510 is disposed on surface 505. Coating 510 comprises a first coating composition 515 comprising a therapeutic agent 520 and a polymer 525 disposed on surface 505 and a second coating composition 530 comprising a metallic material 540 with pores as discussed above, disposed on the first coating composition 515. In this embodiment, the second coating composition 530 is disposed on the first coating composition 515 in the configuration of wavy bands or stripes 550.

FIGS. 5-8 show some examples of configurations of the first coating composition and the second coating composition; however, other configurations of the first coating composition and the second coating composition can be used.

Also, in some embodiments, the second coating composition can be disposed on the first coating composition, as well as, the surface of the medical device. FIG. 9 shows a cross-section view of another embodiment of a coating disposed on at least a portion of a medical device. In this embodiment medical device 600 has a surface 605 and coating 610 is disposed on surface 605 of medical device 600. Coating 610 includes a first coating composition 615 comprising a therapeutic agent 620 and optionally a polymer that is disposed on portions of the surface 605 of medical device 600. A second coating composition 630 comprising a metallic material 640 is disposed on the first coating composition 615, as well as on at least a portion of the surface 605 of the medical device 600. As shown in FIG. 9, the second coating composition 630 when disposed on the first coating composition 615 has an outer surface 630a and a plurality of pores 642. The pores 642 extend from the outer surface 615a of the first coating composition 615 to the outer surface 630a of the second coating composition 630.

In still other embodiments, the coating can comprise a first coating composition comprising a therapeutic agent and optionally a polymer disposed on the surface of a medical device, such as an implantable, intravascular stent and second coating composition comprising a metallic material also disposed on the surface of the medical device. FIG. 10 shows a cross-sectional view of an embodiment of a coating disposed on at least a portion of a medical device. In this embodiment medical device 700 has a surface 705 and a coating 710 disposed on the surface 705 of the medical device 700. Coating 710 includes a first coating composition 715 comprising a therapeutic agent 720 and optionally a polymer disposed on the surface 705 of the medical device 700. The coating 710 also includes a second coating composition 730 comprising a metallic material 740 that is also disposed on the surface 705 of the medical device 700. The second coating composition 730 is substantially free of any polymer. In some embodiments, the second coating composition 730 when applied to the surface 705 can but need not include the pores described above. As shown in FIG. 10, when disposed on the surface 705, both the first coating composition 715 and second coating composition 730 can have the same thickness, h.

Alternatively, as shown in FIG. 11, the thicknesses of the first coating composition 715 and the second coating composition 730 when disposed on the surface 705 of the medical device 700 can be different. As shown in FIG. 11, coating 710 has a first coating composition 715 comprising a therapeutic agent 720 and a polymer 725 and a second coating composition 730 comprising a metallic material 740. When the first coating composition 715 comprises a polymer 725, it may be preferable for the thickness, x, of the second coating composition 730 to be greater than the thickness, y, of the first coating composition 715. Having the thickness x of the second coating composition 730, which is substantially free of any polymer, greater than that of the thickness y of the first coating composition prevents the polymer 725 in the first coating composition 715 from contacting the body lumen. This may eliminate possible adverse effects to the body lumen caused by contact with a polymer.

A. Medical Devices

Suitable medical devices for the present invention include, but are not limited to, stents, surgical staples, cochlear implants, embolic coils, catheters, such as central venous catheters and arterial catheters, guidewires, cannulas, cardiac pacemaker leads or lead tips, cardiac defibrillator leads or lead tips, implantable vascular access ports, blood storage bags, blood tubing, vascular or other grails, intra-aortic balloon pumps, heart valves, cardiovascular sutures, total artificial hearts and ventricular assist pumps, extra-corporeal devices such as blood oxygenators, blood filters, hemodialysis units, hemoperfusion units or plasmapheresis units.

Medical devices which are particularly suitable for the present invention, include any stent for medical purposes, which are known to the skilled artisan. Suitable stents include, for example, vascular stents such as self-expanding stents, balloon expandable stents and sheet deploy able stents. Examples of self-expanding stents are illustrated in U.S. Pat. Nos. 4,655,771 and 4,954,126 issued to Wallsten and 5,061,275 issued to Wallsten et al. Examples of appropriate balloon-expandable stents are shown in U.S. Pat. No. 5,449,373 issued to Pinchasik et al in preferred embodiments, the stent suitable for the present invention is an Express stent. More preferably, the Express stent is an Express™ stent or an Express2™ stent (Boston Scientific. Inc. Natick, Mass.).

The framework of the suitable stents may be formed through various methods as known in the art. The framework may be welded, molded, laser cut, electro-formed, or consist of filaments or fibers which are wound or braided together in order to form a continuous structure.

Medical devices that are suitable for the present invention may be fabricated from metallic, ceramic, polymeric or composite materials or a combination thereof. Preferably, the materials are biocompatible. Metallic material is more preferable. Suitable metallic materials include metals and alloys based on titanium (such as nitinol, nickel titanium alloys, thermo-memory alloy materials); stainless steel; tantalum, nickel-chrome; or certain cobalt alloys including cobalt-chromium-nickel alloys such as Elgiloy® and Phynox®; PERSS (Platinum EnRiched Stainless Steel) and Niobium. Metallic materials also include clad composite filaments, such as those disclosed in WO 94/16646. Preferred, metallic materials include, platinum enriched stainless steel and zirconium and niobium alloys.

Suitable ceramic materials include, but are not limited to, oxides, carbides, or nitrides of the transition elements such as titanium, hafnium, iridium, chromium, aluminum, and zirconium. Silicon based materials, such as silica, may also be used.

Suitable polymeric materials for forming the medical devices may be biostable. Also, the polymeric material may be biodegradable. Suitable polymeric materials include, but are not limited to, styrene isobutylene copolymers, polyetheroxides, polyvinyl alcohol, polyglycolic acid, polylactic acid, polyamides, poly-2-hydroxy-butyrate, polycaprolactone, poly(lactic-co-clycolic)acid, and Teflon.

Polymeric materials may be used for forming the medical device in the present invention include without limitation isobutylene-based polymers, polystyrene-based polymers, polyacrylates, and polyacrylate derivatives, vinyl acetate-based polymers and its copolymers, polyurethane and its copolymers, silicone and its copolymers, ethylene vinyl-acetate, polyethylene terephtalate, thermoplastic elastomers, polyvinyl chloride, polyolefios, cellulosics, polyamides, polyesters, polysulfones, polytetrafluorethylenes, polycarbonates, acrylonitrile butadiene styrene copolymers, acrylics, polylactic acid, polyglycolic acid, polycaprolactone, polylactic acid-polyethylene oxide copolymers, cellulose, collagens, and chitins.

Other polymers that are useful as materials for medical devices include without limitation dacron polyester, poly(ethylene terephthalate), polycarbonate, polymethylmethacrylate, polypropylene, polyalkylene oxalates, polyvinylchloride, polyurethanes, polysiloxanes, nylons, poly(dimethyl siloxane), polycyanoacrylates, polyphosphazenes, poly(amino acids), ethylene glycol I dimethacrylate, poly(methyl methacrylate), poly(2-hydroxyethyl methacrylate), polytetrafluoroethylene poly(HEMA), polyhydroxyalkanoates, polytetrafluorethylene, polycarbonate, poly(glycolide-lactide) co-polymer, polylactic acid, poly(γ-caprolactone), poly(γ-hydroxybutyrate), polydioxanone, poly(γ-ethyl glutamate), polyiminocarbonates, poly(ortho ester), polyanhydrides, alginate, dextran, chitin, cotton, polyglycolic acid, polyurethane, or derivatized versions thereof, i.e., polymers which have been modified to include, for example, attachment sites or cross-linking groups, e.g., RGD, in which the polymers retain their structural integrity while allowing for attachment of cells and molecules, such as proteins, nucleic acids, and the like.

Medical devices may also be made with non-polymeric materials. Examples of useful non-polymeric materials include sterols such as cholesterol, stigmasterol, β-sitosterol and estradiol; cholesteryl esters such as cholesteryl stearate; C12-C24 fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid; C18-C36-mono-, di- and triacylglycerides such as glyceryl monooleate, glyceryl monolinoleate, glyceryl monolaurate, glyceryl monodocosanoate, glyceryl monomyristate, glyceryl monodicenoate, glyceryl dipalmitate, glyceryl didocosanoate, glyceryl dimyristate, glyceryl didecenoate, glyceryl tridocosanoate, glyceryl trimyristate, glyceryl tridecenoate, glycerol tristearate and mixtures thereof; sucrose fatty acid esters such as sucrose distearate and sucrose palmitate; sorbitan fatty acid esters such as sorbitan monostearate, sorbitan monopalmitate and sorbitan tristearate; C16-C18 fatty alcohols such as ceryl alcohol, myristyl alcohol, stearyl alcohol, and cetostearyl alcohol; esters of fatty alcohols and fatty acids such as cetyl palmitate and cetearyl palmitate; anhydrides of fatty acids such as stearic anhydride; phospholipids including phosphatidylcholine (lecithin), phosphatidylserine, phosphatidylethanolamine, phosphatidylinositol, and lysoderivatives thereof; sphingosine and derivatives thereof; sphingomyelins such as stearyl, palmitoyl, and tricosanyl sphingomyelins; ceramides such as stearyl and palmitoyl ceramides; glycosphingolipids; lanolin and lanolin alcohols; and combinations and mixtures thereof. Non-polymeric materials may also include biomaterials such as stem sells, which can be seeded into the medical device prior to implantation. Preferred non-polymeric materials include cholesterol, glyceryl monostearate, glycerol tristearate, stearic acid, stearic anhydride, glyceryl monooleate, glyceryl monolinoleate, and acetylated monoglycerides.

B. Therapeutic Agents

The term “therapeutic agent” as used in the present invention encompasses drugs, genetic materials, and biological materials and can be used interchangeably with “biologically active material”. In one embodiment, the therapeutic agent is an anti-restenotic agent. In other embodiments, the therapeutic agent inhibits smooth muscle cell proliferation, contraction, migration or hyperactivity. Non-limiting examples of suitable therapeutic agent include heparin, heparin derivatives, urokinase, dextrophenylalanine proline arginine chloromethylketone (PPack), enoxaprin, angiopeptin, hirudin, acetylsalicylic acid, tacrolimus, everolimus, zotarolimus, rapamycin (sirolimus), pimecrolimus, amlodipine, doxazosin, glucocorticoids, betamethasone, dexamethasone, prednisolone, corticosterone, budesonide, sulfasalazine, rosiglitazone, mycophenolic acid, mesalamine, paclitaxel, 5-fluorouracil cisplatin, vinblastine, vincristine, epothilones, methotrexate, azathioprine, adriamycin, mutamycin, endostatin, angiostatin, thymidine kinase inhibitors, cladribine, lidocaine, bupivacaine, ropivacaine, D-Phe-Pro-Arg chloromethyl ketone, platelet receptor antagonists, anti-thrombin antibodies, anti-platelet receptor antibodies, aspirin, dipyridamole, protamine, hirudin, prostaglandin inhibitors, platelet inhibitors, trapidil, liprostin, tick antiplatelet peptides, 5-azacytidine, vascular endothelial growth factors, growth factor receptors, transcriptional activators, translational promoters, antiproliferative agents, growth factor inhibitors, growth factor receptor antagonists, transcriptional repressors, translational, repressors, replication inhibitors, inhibitory antibodies, antibodies directed against growth factors, bifunctional molecules consisting of a growth factor and a cytotoxin, bifunctional molecules consisting of an antibody and a cytotoxin, cholesterol lowering agents, vasodilating agents, agents which interfere with endogenous vasoactive mechanisms, antioxidants, protocol, antibiotic agents, penicillin, cefoxitin, oxacillin, tobranycin, angiogenic substances, fibroblast growth factors, estrogen, estradiol (E2), estriol (E3), 17-beta estradiol, digoxin, beta blockers, captopril, enalopril, statins, steroids, vitamins, paclitaxel (as well as its derivatives, analogs or paclitaxel bound to proteins, e.g. Abraxane™) 2′-succinyl-taxol, 2′-succinyl-taxol triethanolamine, 2′-glutaryl-taxol, 2′-glutaryl-taxol triethanolamine salt, 2′-O-ester with N-(dimethylaminoethyl) glutamine, 2′-O-ester with N-(dimethylaminoethyl) glutamide hydrochloride salt, nitroglycerin, nitrous oxides, nitric oxides, antibiotics, aspirins, digitalis, estrogen, estradiol and glycosides. In one embodiment, the therapeutic agent is a smooth muscle cell inhibitor or antibiotic. In a preferred embodiment, the therapeutic agent is taxol (e.g., Taxol®), or its analogs or derivatives. In another preferred embodiment, the therapeutic agent is paclitaxel, or its analogs or derivatives. In yet another preferred embodiment, the therapeutic agent is an antibiotic such as erythromycin, amphotericin, rapamycin, adriamycin, etc.

The term “genetic materials” means DNA or RNA, including, without limitation, of DNA/RNA encoding a useful protein stated below, intended to be inserted into a human body including viral vectors and non-viral vectors.

The term “biological materials” include cells, yeasts, bacteria, proteins, peptides, cytokines and hormones. Examples for peptides and proteins include vascular endothelial growth factor (VEGF), transforming growth factor (TGF), fibroblast growth factor (FGF), epidermal growth factor (EGF), cartilage growth factor (CGF), nerve growth factor (NGF), keratinocyte growth factor (KGF), skeletal growth factor (SGF), osteoblast-derived growth factor (BDGF), hepatocyte growth factor (HGF), insulin-like growth factor (IGF), cytokine growth factors (CGF), platelet-derived growth factor (PDGF), hypoxia inducible factor-1 (HIF-1), stem cell derived factor (SDF), stem cell factor (SCF), endothelial cell growth supplement (ECGS), granulocyte macrophage colony stimulating factor (GM-CSF), growth differentiation factor (GDF), integrin modulating factor (IMF), calmodulin (CaM), thymidine kinase (TK), tumor necrosis factor (TNF), growth hormone (GH), bone morphogenic protein (BMP) (e.g., BMP-2, BMP-3, BMP-4, BMP-5, BMP-6 (Vgr-1), BMP-7 (PO-1), BMP-8, BMP-9, BMP-10, BMP-11, BMP-12, BMP-14, BMP-15, BMP-16, etc.), matrix metalloproteinase (MMP), tissue inhibitor of matrix metalloproteinase (TIMP), cytokines, interleukin (e.g., IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-15, etc.), lymphokines, interferon, integrin, collagen (all types), elastin, fibrillins, fibronectin, vitronectin, laminin, glycosaminoglycans, proteoglycans, transferrin, cytotactin, cell binding domains (e.g., RGD), and tenascin. Currently preferred BMP\'s are BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7. These dimeric proteins can be provided as homodimers, heterodimers, or combinations thereof, alone or together with other molecules. Cells can be of human origin (autologous or allogeneic) or from an animal source (xenogeneic), genetically engineered. If desired, to deliver proteins of interest at the transplant site. The delivery media can be formulated as needed to maintain cell function and viability. Cells include progenitor cells (e.g., endothelial progenitor cells), stem cells (e.g., mesenchymal, hematopoietic, neuronal), stromal cells, parenchymal cells, undifferentiated cells, fibroblasts, macrophage, and satellite cells.

Other non-genetic therapeutic agents include: anti-thrombogenic agents such as heparin, heparin derivatives, urokinase, and PPack (dextrophenylalanine proline arginine chloromethylketone); anti-proliferative agents such as enoxaprin, angiopeptin, or monoclonal antibodies capable of blocking smooth muscle cell proliferation, hirudin, acetylsalicylic acid, tacrolimus, everolimus, amlodipine and doxazosin; anti-inflammatory agents such as glucocorticoids, betamethasone, dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, rosiglitazone, mycophenolic acid and mesalamine; anti-neoplastic/anti-proliferative/anti-miotic agents such as paclitaxel, 5-fluorouracil, cisplatin, vinblastine, vincristine, epothilones, methotrexate, azathioprine, adriamycin and mutamycin; endostatin, angiostatin and thymidine kinase inhibitors, cladribine, taxol and its analogs or derivatives; anesthetic agents such as lidocaine, bupivacaine, and ropivacaine; anti-coagulants such as D-Phe-Pro-Arg chloromethyl ketone, an RGD peptide-containing compound, heparin, antithrombin compounds, platelet receptor antagonists, anti-thrombin antibodies, anti-platelet receptor antibodies, aspirin (aspirin is also classified as an analgesic, antipyretic and anti-inflammatory drug), dipyridamole, protamine, hirudin, prostaglandin inhibitors, platelet inhibitors, antiplatelet agents such as trapidil or liprostin and tick antiplatelet peptides; DNA demethylating drugs such as 5-azacytidine, which is also categorized as a RNA or DNA metabolite that inhibit cell growth and induce apoptosis in certain cancer cells; vascular cell growth promoters such as growth factors, vascular endothelial growth factors (VEGF, all types including VEGF-2), growth factor receptors, transcriptional activators, and translational promoters;

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stats Patent Info
Application #
US 20120323308 A1
Publish Date
12/20/2012
Document #
13596729
File Date
08/28/2012
USPTO Class
623/116
Other USPTO Classes
623/142, 623/143
International Class
61F2/82
Drawings
13


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Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor   Arterial Prosthesis (i.e., Blood Vessel)   Stent Structure   Having Multiple Connected Bodies