Intravascular stent and method

• US 5,837,008 A
• Filed: 04/27/1995
• Issued: 11/17/1998
• Est. Priority Date: 04/26/1993
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Berg, Eric P., Dror, Michael, Tuch, Ronald J., Wolff, Rodney G.
• Primary Examiner(s): Yu, Mickey
• Assistant Examiner(s): CUDDIHY, FRANCIS KEVIN
• Application Number:
  US08/429,969
• Time in Patent Office: 1,300 Days
• Field of Search: 600/36, 606/191-200, 623/1, 623/11-12
• US Class Current: 128/898
• 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 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2240/001 Designing or manufacturing processes
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61L 2300/222 Steroids, e.g. corticosteroids
• 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 2300/42 Anti-thrombotic agents, anticoagulants, anti-platelet agents
• 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 2300/608 having two or more layers
• CPC Class Codes: A61L 31/10 Macromolecular materials
• 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

Abstract

A method for making an intravascular stent by applying to the body of a stent a solution which includes a solvent, a polymer dissolved in the solvent and a therapeutic substance dispersed in the solvent and then evaporating the solvent. The inclusion of a polymer in intimate contact with a drug on the stent allows the drug to be retained on the stent during expansion of the stent and also controls the administration of drug following implantation. The adhesion of the coating and the rate at which the drug is delivered can be controlled by the selection of an appropriate bioabsorbable or biostable polymer and the ratio of drug to polymer in the solution. By this method, drugs such as dexamethasone can be applied to a stent, retained on a stent during expansion of the stent and elute at a controlled rate.

Claims

1. A method for delivery of a therapeutic substance to the interior of a body lumen comprising the steps of:

(a) providing a generally cylindrical, radially expandable stent body having a surface;

(b) applying to the surface a solution which includes a solvent, a polymer dissolved in the solvent and a therapeutic substance dispersed in the solvent;

(c) evaporating the solvent to provide a coat of therapeutic substance and polymer on the surface;

(d) repeating steps (b) and (c) until a plurality of coats of therapeutic substance and polymer are on the surface;

(e) introducing the stent body and the plurality of coats of therapeutic substance and polymer transluminally into a selected portion of the body lumen; and

(f) radially expanding the stent body and the plurality of coats of therapeutic substance and polymer into contact with the body lumen such that the plurality of coats of therapeutic substance and polymer are retained on the surface.

2. A method according to claim 1 wherein the surface is a polymeric surface.

3. A method according to claim 1 wherein the solution is applied by spraying.

4. A method according to claim 1 wherein the solution is applied by immersion.

5. A method according to claim 1 wherein the polymer is a bioabsorbable polymer.

6. A method according to claim 5 wherein the polymer is selected from the group consisting of poly(L-lactic acid), poly(lactide-co-glycolide) and poly(hydroxybutyrate-co-valerate).

7. A method according to claim 1 wherein the polymer is a biostable polymer.

8. A method according to claim 7 wherein the polymer is selected from the group consisting of silicones, polyurethanes, polyesters, vinyl homopolymers and copolymers, acrylate homopolymers and copolymers, polyethers and cellulosics.

9. A method according to claim 1 wherein the ratio of therapeutic substance to dissolved polymer in the solution is in the range of about 10:

1 to 1;

100.

10. A method according to claim 1 wherein the therapeutic substance is selected from the group consisting of glucocorticoids, dexamethasone, dexamethasone sodium phosphate, anticoagulants, heparin, hirudin, tick anticoagulant peptide, angiopeptin, antimitotic agents, and oligonucleotides.

11. A method for delivery of a therapeutic substance to the interior of a body lumen comprising the steps of:

(a) providing a generally cylindrical, radially expandable stent body having a metal surface;

(b) applying to the metal surface a solution which includes a solvent, a polymer dissolved in the solvent and a therapeutic substance dispersed in the solvent;

(c) evaporating the solvent to provide a coat of therapeutic substance and polymer on the metal surface;

(d) repeating steps (b) and (c) until a plurality of coats of therapeutic substance and polymer are on the metal surface;

(e) introducing the stent body and the plurality of coats of therapeutic substance and polymer transluminally into a selected portion of the body lumen; and

(f) radially expanding the stent body and the plurality of coats of therapeutic substance and polymer into contact with the body lumen such that the plurality of coats of therapeutic substance and polymer are retained on the metal surface.

12. A method according to claim 11 wherein the metal surface is a low memory metal surface.

13. A method according to claim 11 wherein the metal surface is a stainless steel surface.

14. A method according to claim 11 wherein the metal surface is a tantalum surface.

15. A method according to claim 11 wherein the metal surface is a metal wire surface.

16. A method according to claim 11 wherein the metal surface comprises a plurality of reversing bends which permits the stent body to be expanded from a first diameter to a second, expanded diameter.

17. A method according to claim 11 wherein the metal surface is on an interior portion of the stent body.

18. A method according to claim 11 wherein the metal surface is on an exterior portion of the stent body.

19. A method according to claim 11 wherein the solution is applied by spraying.

20. A method according to claim 11 wherein the solution is applied by immersion.

21. A method according to claim 11 wherein the polymer is a bioabsorbable polymer.

22. A method according to claim 21 wherein the polymer is selected from the group consisting of poly(L-lactic acid), poly(lactide-co-glycolide) and poly(hydroxybutyrate-co-valerate).

23. A method according to claim 11 wherein the polymer is a biostable polymer.

24. A method according to claim 23 wherein the polymer is selected from the group consisting of silicones, polyurethanes, polyesters, vinyl homopolymers and copolymers, acrylate homopolymers and copolymers, polyethers and cellulosics.

25. A method according to claim 11 wherein the ratio of therapeutic substance to dissolved polymer in the solution is in the range of about 10:

1 to 1;

100.

26. A method according to claim 11 wherein the therapeutic substance is selected from the group consisting of glucocorticoids, dexamethasone, dexamethasone sodium phosphate, anticoagulants, heparin, hirudin, tick anticoagulant peptide, angiopeptin, antimitotic agents, and oligonucleotides.

27. A method for delivery of a therapeutic substance to the interior of a body lumen comprising the steps of:

(a) providing a generally cylindrical, radially expandable stent body having a surface;

(b) applying to the surface a solution which includes a solvent, a polymer dissolved in the solvent and a therapeutic substance dispersed in the solvent;

(c) evaporating the solvent to provide a coat of therapeutic substance and polymer on the surface;

(d) repeating steps (b) and (c) until a plurality of coats of therapeutic substance and polymer are on the surface such that the ratio of therapeutic substance to dissolved polymer is varied in the plurality of coats;

(e) introducing the stent body and the plurality of coats of therapeutic substance and polymer transluminally into a selected portion of the body lumen; and

(f) radially expanding the stent body and the plurality of coats of therapeutic substance and polymer into contact with the body lumen such that the plurality of coats of therapeutic substance and polymer are retained on the metal surface.

28. A method according to claim 27 wherein the ratio of therapeutic substance to dissolved polymer is higher in an outer coat than in an inner coat.

29. A method according to claim 27 wherein the solution is applied by spraying.

30. A method according to claim 27 wherein the solution is applied by immersion.

31. A method according to claim 27 wherein the polymer is a bioabsorbable polymer.

32. A method according to claim 31 wherein the polymer is selected from the group consisting of poly(L-lactic acid), poly(lactide-co-glycolide) and poly(hydroxybutyrate-co-valerate).

33. A method according to claim 27 wherein the polymer is a biostable polymer.

34. A method according to claim 33 wherein the polymer is selected from the group consisting of silicones, polyurethanes, polyesters, vinyl homopolymers and copolymers, acrylate homopolymers and copolymers polyethers and cellulosics.

35. A method according to claim 27 wherein the ratio of therapeutic substance to dissolved polymer in the solution is in the range of about 10:

1 to 1;

100.

36. A method according to claim 27 wherein the therapeutic substance is selected from the group consisting of glucocorticoids, dexamethasone, dexamethasone sodium phosphate, anticoagulants, heparin, hirudin, tick anticoagulant peptide, angiopeptin, antimitotic agents, and oligonucleotides.