Biodegradable medical implant with encapsulated buffering agent

• US 20050267565A1
• Filed: 05/28/2004
• Published: 12/01/2005
• Est. Priority Date: 05/28/2004
• Status: Active Grant

• Current Assignee: Cardinal Health Switzerland 515 GmbH (Cardinal Health, Inc.)
• Original Assignee: Cordis Corporation (Cardinal Health, Inc.)
• Inventors: Dave, Vipul Bhupendra, Landau, George, Patel, Premal
• Granted Patent: US 7,785,615 B2
• Time in Patent Office: Days
• US Class Current: 623/1.150
• CPC Class Codes: A61L 27/446 with other specific inorganic fillers other than those covered by A61L27/443 or A61L27/46
• CPC Class Codes: A61L 27/48 with macromolecular fillers
• CPC Class Codes: A61L 31/128 containing other specific inorganic fillers not covered by A61L31/126 or A61L31/127
• CPC Class Codes: A61L 31/129 containing macromolecular fillers

Abstract

A medical device for placement at a site in a patient'"'"'s body and for controlling pH levels at the site in the patient'"'"'s body includes one or more structural components made of a first biodegradable and/or bioabsorbable material or, alternatively, one or more structural components having a coating thereon made of a first biodegradable and/or bioabsorbable material. The device also includes a buffering agent and at least one second biodegradable and/or bioabsorbable material on or in the one or more structural components, or alternatively, on or in the coating on the one or more structural components. The at least one second biodegradable and/or bioabsorbable material encapsulates the buffering agent and the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material in response to hydrolysis of the first biodegradable and/or bioabsorbable material. Additionally, the device can include a drug that is either also encapsulated by the at least one second biodegradable and/or bioabsorbable material or is included with the first biodegradable and/or bioabsorbable material.

Claims

1. A medical device for placement at a site in a patient'"'"'s body and for controlling pH levels at the site in the patient'"'"'s body, the device comprising:

one or more structural components made of a first biodegradable and/or bioabsorbable material;

a buffering agent; and

at least one second biodegradable and/or bioabsorbable material on or in the one or more structural components, the at least one second biodegradable and/or bioabsorbable material encapsulating the buffering agent, the buffering agent being dispersed from the at least one second biodegradable and/or bioabsorbable material in response to hydrolysis of the first biodegradable and/or bioabsorbable material.

2. The medical device according to claim 1, wherein the first biodegradable and/or bioabsorbable material is a bulk erodible polymer that is either a homopolymer, a copolymer or a blend of polymers.

3. The medical device according to claim 2, wherein the at least one second biodegradable and/or bioabsorbable material is a surface erodible polymer.

4. The medical device according to claim 2, wherein the at least one second biodegradable and/or bioabsorbable material is a bulk erodible polymer.

5. The medical device according to claim 2, wherein the bulk erodible polymer is a polyester.

6. The medical device according to claim 5, wherein the polyester belongs to the poly(alpha-hydroxy acids) group.

7. The medical device according to claim 6, wherein the polyester is an aliphatic polyester.

8. The medical device according to claim 7, wherein the aliphatic polyester is selected from the group consisting of poly (lactic acid), poly (glycolic acid), poly (caprolactone), poly (p-dioxanone) and poly (trimethylene carbonate).

9. The medical device according to claim 2, wherein the bulk erodible polymer is an amino acid derived polymer selected from the group consisting of poly(iminocarbonates), phosphorous containing polymers, poly(phosphazenes), poly(phosphoesters) and poly(ester amide).

10. The medical device according to claim 1, wherein the at least one second biodegradable and/or bioabsorbable material is a either a homo polymer, a copolymer or a blend of polymers.

11. The medical device according to claim 10, wherein the at least one second biodegradable and/or bioabsorbable material is a polymer selected from the group consisting of polysaccharides, poly(orthoesters), proteins, water soluble polymers and PEG based copolymers.

12. The medical device according to claim 11, wherein the at least one second absorbable material is in the form of a microparticle.

13. The medical device according to claim 11, wherein the at least one second biodegradable and/or bioabsorbable material is in the form of a nanoparticle.

14. The medical device according to claim 1, further comprising a drug encapsulated by the at least one second biodegradable and/or bioabsorbable material.

15. The medical device according to claim 1, further comprising a drug with the first biodegradable and/or bioabsorbable material.

16. The medical device according to claim 1, wherein the buffering agent is selected from the group consisting of calcium hydroxyapatite, carbonated apatite, tricalcium phosphate, calcium carbonate, sodium bicarbonate, calcium phosphates, carbonated calcium phosphates, magnesium hydroxide, amine monomers, and lactate dehydrogenase.

17. The medical device according to claim 1, wherein the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material at pH<

7.4.

18. The medical device according to claim 17, wherein the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material at pH ranging from about 3 to about 6.

19. The medical device according to claim 18, wherein the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material at pH of about 5.

20. The medical device according to claim 17, wherein the buffering agent raises pH at the site after being dispersed from the at least one second biodegradable and/or bioabsorbable material.

21. The medical device according to claim 20, wherein the buffering agent raises pH to about 7.4 at the site after being dispersed from the at least one second biodegradable and/or bioabsorbable material.

22. The medical device according to claim 1, wherein the device is a stent.

23. The medical device according to claim 1, wherein the device is a valve.

24. The medical device according to claim 1, wherein the device is selected from the group consisting of clamps, screws, plates, clips, staples, hooks, buttons, snaps, prosthetics, grafts, injectable polymers, vertebrae discs, anchoring devices, suture anchors, septal occlusion devices, injectable defect fillers, preformed defect fillers, bone waxes, cartilage replacements, spinal fixation devices, drug delivery devices and foams.

25. A medical device for placement at a site in a patient'"'"'s body and for controlling pH levels at the site in the patient'"'"'s body, the device comprising:

one or more structural components having a coating thereon, the coating made of a first biodegradable and/or bioabsorbable material;

a buffering agent; and

at least one second biodegradable and/or bioabsorbable material on or in the coating on the one or more structural components, the at least one second biodegradable and/or bioabsorbable material encapsulating the buffering agent, the buffering agent being dispersed from the at least one second biodegradable and/or bioabsorbable material in response to hydrolysis of the first biodegradable and/or bioabsorbable material.

26. The medical device according to claim 25, wherein the first bioabsorbable material is a bulk erodible polymer that is either a homopolymer, a copolymer or a blend of polymers.

27. The medical device according to claim 26, wherein the at least one second biodegradable and/or bioabsorbable material is a surface erodible polymer.

28. The medical device according to claim 26, wherein the at least one second biodegradable and/or bioabsorbable material is a bulk erodible polymer.

29. The medical device according to claim 26, wherein the bulk erodible polymer is a polyester.

30. The medical device according to claim 29, wherein the polyester belongs to the poly(alpha-hydroxy acids) group.

31. The medical device according to claim 30, wherein the polyester is an aliphatic polyester.

32. The medical device according to claim 31, wherein the aliphatic polyester is selected from the group consisting of poly (lactic acid), poly (glycolic acid), poly(caprolactone), poly(p-dioxanone) and poly(trimethylene carbonate).

33. The medical device according to claim 26, wherein the bulk erodible polymer is an amino acid derived polymer selected from the group consisting of poly(iminocarbonates), phosphorous containing polymers, poly(phosphazenes), poly(phosphoesters) and poly(ester amide).

34. The medical device according to claim 25, wherein the at least one second biodegradable and/or bioabsorbable material is a either a homopolymer, a copolymer or a blend of polymers.

35. The medical device according to claim 34, wherein the at least one second biodegradable and/or bioabsorbable material is a polymer selected from the group consisting of polysaccharides, poly(orthoesters), proteins, water soluble polymers and PEG based copolymers.

36. The medical device according to claim 35, wherein the at least one second biodegradable and/or bioabsorbable material is in the form of a microparticle.

37. The medical device according to claim 35, wherein the at least one second biodegradable and/or bioabsorbable material is in the form of a nanoparticle.

38. The medical device according to claim 25, further comprising a drug encapsulated by the at least one second biodegradable and/or bioabsorbable material.

39. The medical device according to claim 25, further comprising a drug with the first biodegradable and/or bioabsorbable material.

40. The medical device according to claim 25, wherein the buffering agent is selected from the group consisting of calcium hydroxyapatite, carbonated apatite, tricalcium phosphate, calcium carbonate, sodium bicarbonate, calcium phosphates, carbonated calcium phosphates, magnesium hydroxide, amine monomers, and lactate dehydrogenase.

41. The medical device according to claim 25, wherein the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material at pH<

7.4.

42. The medical device according to claim 41, wherein the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material at pH ranging from about 3 to about 6.

43. The medical device according to claim 42, wherein the buffering agent is dispersed from the at least one second biodegradable and/or bioabsorbable material at pH of about 5.

44. The medical device according to claim 41, wherein the buffering agent raises pH at the site after being dispersed from the at least one second biodegradable and/or bioabsorbable material.

45. The medical device according to claim 44, wherein the buffering agent raises pH to about 7.4 at the site after being dispersed from the at least one second biodegradable and/or bioabsorbable material.

46. The medical device according to claim 25, wherein the device is a stent.

47. The medical device according to claim 25, wherein the device is a valve.

48. The medical device according to claim 25, wherein the device is selected from the group consisting of clamps, screws, plates, clips, staples, hooks, buttons, snaps, prosthetics, grafts, injectable polymers, vertebrae discs, anchoring devices, suture anchors, septal occlusion devices, injectable defect fillers, preformed defect fillers, bone waxes, cartilage replacements, spinal fixation devices, drug delivery devices and foams.