Method for manufacturing particles for use in forming a resorbable implant for stimulating bone growth
View Patent ↗A bone-growth stimulating composition for forming a resorbable implant, methods for making such a composition and a corresponding putty/paste material. In some embodiments of the invention, such a material includes a plurality of particles having a predetermined size and comprising a first calcium sulfate compound and a resorbable polymer in a predetermined weight ratio. Methods for making such a material include rotating calcium sulfate powder in a drum at a first predetermined drum speed, spraying of a resorbable polymer solution at a predetermined rate on the calcium sulfate powder over a predetermined period of time and drying the resulting particles. Such compositions allow resorption rates of the implant composition in vivo to be controlled, and my vary between eight and twenty-four weeks (for example), which can be matched to substantially correspond to a rate of bone growth in a particular application. The implant composition of the present invention can be used for the repair, augmentation, and other treatment of bone.
1. A method for manufacturing particles for use in forming a resorbable implant for stimulating bone growth, the method comprising: rotating calcium sulfate powder in a drum at a first predetermined drum speed; a first spraying of a resorbable polymer solution at a first predetermined rate on the calcium sulfate powder over a first predetermined period of time; and drying the resulting particles, wherein said resorbable polymer solution comprises a resorbable polymer comprising aliphatic polyester of alpha-hydroxy acid derivatives, poly(desaminotyrosyl-tyrosine alkyl ester carbonate), or therapeutic polymers containing salicylate, and a solvent.
2. The method according to claim 1 , wherein the first predetermined drum speed is between about 200 and 400 RPM during spraying.
3. The method according to claim 1 , wherein first predetermined drum speed is between about 300 and 400 RPM during spraying.
4. The method according to claim 1 , wherein the first predetermined drum speed is about 350 RPM during spraying.
5. The method according to claim 1 , wherein the particles comprise about 0.1% to about 22% (w/w) of a resorbable polymer.
6. The method according to claim 1 , wherein the first predetermined rate comprises between about 50 and 70 grams per minute.
7. The method according to claim 1 , wherein the first predetermined rate comprises about 60 grams per minute.
8. The method according to claim 1 , wherein the first predetermined period of time comprises between about 10 to 20 minutes.
9. The method according to claim 1 , wherein the first predetermined period of time comprises about 15 minutes.
10. The method according to claim 1 , wherein the solvent comprises methylene chloride.
11. The method according to claim 1 , wherein the resorbable polymer comprises L-polylactide.
12. The method according to claim 1 , wherein a weight ratio of the resorbable polymer to the solvent in the resorbable polymer solution is between about 1:200 and about 1:300.
13. The method according to claim 1 , wherein a weight ratio of the resorbable polymer to the solvent in the resorbable polymer solution is about 1:250.
14. The method according to claim 1 , further comprising a second spraying the resorbable polymer solution after completing the first spraying.
15. The method according to claim 14 , wherein the second spraying is carried out over a second predetermined period of time.
16. The method according to claim 14 , wherein the second spraying is carried out at a second predetermined rate.
17. The method according to claim 14 , wherein the second spraying is carried out at a second predetermined drum speed.
18. The method according to claim 17 , wherein the second predetermined drum speed is faster than the first predetermined drum speed.
19. The method according to claim 17 , wherein the second predetermined drum speed is between about 300 to about 500 RPM.
20. The method according to claim 17 , wherein the second predetermined drum speed is about 400 RPM.
21. The method according to claim 15 , wherein the second predetermined period of time is between about 100 and 300 minutes.
22. The method according to claim 15 , wherein the second predetermined period of time is between about 150 and 250 minutes.
23. The method according to claim 16 , wherein the second predetermined rate is between about 30 and 50 grams per minute.
24. The method according to claim 16 , wherein the second predetermined rate is about 40 grams per minute.
25. The method according to claim 1 , wherein said drying comprises spinning the particles in the drum for a further period of time.
26. The method according to claim 25 , wherein said further period of time is between about 40 and about 80 minutes.
27. The method according to claim 25 , wherein said further period of time is about 60 minutes.
28. The method according to claim 25 , wherein the drum is rotated at a further predetermined drum speed.
29. The method according to claim 28 , wherein said further predetermined drum speed is between about 100 and about 300 RPM.
30. The method according to claim 28 , wherein said further predetermined drum speed is about 250 RPM.
31. The method according to claim 1 , wherein the calcium sulfate powder is rotated in the drum at a temperature between about 40° C. and about 80° C.
32. The method according to claim 1 , wherein the calcium sulfate powder in rotated is the drum at a temperature about 50° C.
33. The method according to claim 1 , wherein said poly(desaminotyrosyl-tyrosine alkyl ester carbonate) comprises poly(desaminotyrosyl-tyrosine ethyl ester carbonates), poly(desaminotyrosyl-tyrosine butyl ester carbonates), poly(desaminotyrosyl-tyrosine hexyl ester carbonates), or poly(desaminotyrosyl-tyrosine octyl ester carbonates).
34. The method according to claim 1 , wherein said aliphatic polyester of alpha-hydroxy acid derivatives is a polylactide.
35. The method according to claim 1 , wherein said aliphatic polyester of alpha-hydroxy acid derivatives is polyglycolide, polydioxanone, or poly ε-caprolactone.
36. A method of manufacturing polymer containing particles as an implant material for stimulating bone growth, comprising:
(a) rotating powder of a calcium sulfate compound comprising calcium sulfate dihydrate, calcium sulfate hemihydrate or mixture thereof, in a drum at a first predetermined drum speed:
(b) spraying a resorbable polymer solution with a first predetermined rate on the powder at the first predetermined drum speed over a first predetermined period of time;
(c) then spraying said resorbable polymer solution on the powder with a second predetermined rate lower than the first predetermined rate at a second predetermined drum speed faster than the first predetermined drum speed over a second predetermined period of time; and
(d) drying resulting particles.
37. The method according to claim 36 , wherein the first predetermined rate comprises between about 50 and 70 grams per minute.
38. The method according to claim 36 , wherein the first predetermined drum speed is between about 200 and 400 RPM.
39. The method according to claim 36 , wherein the first predetermined period of time comprises between about 10 to 20 minutes.
40. The method according to claim 36 , wherein the second predetermined rate is between about 30 and 50 grams per minute.
41. The method according to claim 36 , wherein the second predetermined drum speed is about 10% to 20% faster than the first predetermined drum speed.
42. The method according to claim 41 , wherein the second predetermined drum speed is between about 300 to about 500 RPM.
43. The method according to claim 36 , wherein the second predetermined period of time is between about 100 and 300 minutes.
44. The method according to claim 36 , wherein drying comprises spinning the particles in the drum for a third period of time.
45. The method according to claim 44 , wherein the third period of time is between about 40 and about 80 minutes.
46. The method according to claim 44 , wherein the drum is rotated at a third predetermined drum speed about 25-50% slower than the second predetermined drum speed.
47. The method according to claim 46 , wherein the third predetermined drum speed is between about 100 and about 300 RPM.
48. The method according to claim 36 , wherein a weight ratio of the resorbable polymer to the solvent in the resorbable polymer solution is between about 1:200 and about 1:300.
49. The method according to claim 36 , wherein the solvent comprises methylene chloride.
50. The method according to claim 36 , wherein said aliphatic polyester of alpha-hydroxy acid derivatives is a polylactide.
51. The method according to claim 36 , wherein said aliphatic polyester of alpha-hydroxy acid derivatives is polyglycolide, polydioxanone, or poly ε-caprolactone.
52. The method according to claim 36 , wherein said poly(desaminotyrosyl-tyrosine alkyl ester carbonate) comprises poly(desaminotyrosyl-tyrosine ethyl ester carbonates), poly(desaminotyrosyl-tyrosine butyl ester carbonates), poly(desaminotyrosyl-tyrosine hexyl ester carbonates), or poly(desaminotyrosyl-tyrosine octyl ester carbonates).
53. The method according to claim 36 , wherein the particles comprise about 0.1% to about 22% (w/w) of a resorbable polymer.