Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
1997-09-02
2001-10-30
Hartley, Michael G. (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S433000, C424S423000, C424S426000, C424S484000
Reexamination Certificate
active
06309659
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns prosthetic materials. More particularly, it concerns a biocompatible material that exhibits reverse phase behavior.
BACKGROUND ART
Osteogenic bone repair materials are known in the art. These materials contain an osteogenic material, such as demineralized bone powder in a carrier, such as glycerol. See, e.g., U.S. Pat. No. 5,290,558, issued Mar. 1, 1994 to O'Leary et al., and U.S. Pat. No. 5,284,655, issued Feb. 8, 1994 to Bogdansky et al.
The carrier of the bone material in the art is a liquid, having a viscosity generally somewhere between runny to paste-like. “Runny” bone repair compositions have the advantage of being relatively easy to apply to and fill a bone defect, however, they are disadvantageous in that the material also tends to readily flow from the defect site. Conversely, bone repair compositions with a “paste-like” consistency are harder to apply to a defect, yet tend to remain positioned at the defect once applied. Additionally, when any of the bone repair compositions in the art are placed in vivo and become warmed, they become even less viscous; the decrease in viscosity is due to the addition of thermal energy to the composition.
Accordingly, there is a need for a bone repair composition that is easy to apply to a defect site, and which remains positioned at the site once placed at the site.
DISCLOSURE OF THE INVENTION
Disclosed is a biocompatible composition to facilitate repair of connective tissues. The composition can comprise demineralized bone powder, and, a carrier comprising a means for achieving reverse phase thermodynamic characteristics when mixed with the bone powder. The composition can be substantially liquid at 0° C., and substantially more viscous at 35° C., such that the composition has a consistency like that of paste floor wax or like solid shoe wax. The means for achieving reverse phase characteristics can comprise a block copolymer, such as a poly(oxyalkylene) block copolymer, which can be a poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) triblock copolymer. The triblock copolymer can be a compound of the formula:
The means for achieving reverse phase characteristics comprises a poloxamer, such as poloxamer 407. The block copolymer can be a solid dispersed in a biocompatible solvent such as sterile water.
Preferably, the composition comprises a carrier of 25 weight percent of a block copolymer dispersed in 75 weight percent of a biocompatible solvent. To vary the consistency of the composition, the weight percentage of demineralized bone powder or other solid can be varied relative to the weight percentage of the carrier in the composition. For example, a paste-like form of the composition comprises 50 weight percent of bone powder and 50 weight percent of a carrier. A gel-like embodiment of the composition comprises 30 weight percent of bone powder and 70 weight percent of a carrier.
The bone powder of the composition can comprise particles with a median length to a median thickness ratio of about 1.742:1, a mean length of 0.25-1 mm (250-1,000 microns), and a mean thickness of about 0.5 mm (500 microns).
Also disclosed is a method to facilitate the development of bone tissue, said method comprising: providing a biocompatible connective tissue repair composition comprising demineralized bone powder, and, a carrier comprising a means for achieving reverse phase thermodynamic characteristics when mixed with the bone powder; and, placing the composition in a bony defect of a mammal. A prosthetic object can also be placed in the bony defect. The method can also comprise coating a portion of the prosthetic object with the biocompatible composition, and in this embodiment the step of placing the composition and the step of placing a prosthetic object can be contemporaneous.
MODES FOR CARRYING OUT INVENTION
Definitions
By “reverse phase” or “reverse thermal behavior” is intended a material that exhibits a physical property of becoming more viscous or solidified upon addition of thermal energy. It is believed that the solidification occurs by a mechanism other than that due to evaporation and corresponding loss of liquid.
As used herein, “ambient temperature” is 25° C., plus or minus 5° C.
As used herein, “body temperature” is 37° C., plus or minus 5° C.
As used herein, a “bony defect” or “bone defect site” is bony environment of a mammal which comprises some viable bone tissue. The defect can be congenital, caused by trauma, or caused by disease.
“Osteoinductive” materials cause undifferentiated cells to differentiate into a committed bone cell lines.
“Osteoconductive” materials provide support for cells of a bone cell lineage, e.g., permitting cells of a bone cell lineage to grow along or through a matrix or lattice.
Preferred Modes
In a preferred embodiment, the composition of the present invention is a flowable liquid when applied to a bony defect, whereupon the composition becomes increasingly solidified or viscous as it warms to ambient temperature and is further solidified as it warms to body temperature. Upon being warmed to body temperature, a preferred composition of the invention is a solid or highly viscous fluid. The reverse phase compositions in accordance with the invention are significantly different in principle from bone repair materials in the art, and do not function in the same way.
The composition comprises a therapeutic material for treating one or more connective tissues; and, a carrier. The therapeutic material can be a material to facilitate repair of connective tissues, i.e., a “connective tissue repair material.” The carrier achieves reverse phase characteristics when mixed with the therapeutic material.
The therapeutic material can be a material that is osteoinductive, osteoconductive, or a material that is osteoinductive and osteoconductive. The therapeutic material can be xenogeneic, allogeneic, or autogenic. The therapeutic material can be alloplastic. As appreciated by one of ordinary skill in the art, the therapeutic material can comprise combinations of various therapeutic materials.
Examples of osteoinductive material include but are not limited to bone powder (mineralized or demineralized), tissue growth factor beta (TGF-&bgr;) types 1 through 13, bone morphogenetic protein (BMP) types 1 through 15, or combinations thereof.
Examples of therapeutic materials that are osteoconductive include but are not limited to xenogeneic bone (mineralized or demineralized); the xenogeneic bone can also be subjected to deproteination. Presently preferred xenogeneic sources are porcine and bovine.
Therapeutic materials that are osteoinductive and osteoconductive include particulate human allograft, e.g., of demineralized bone.
Examples of alloplastic materials comprise gypsum, coralline hydroxyapatite, synthetic hydroxyapatite, calcium carbonate, calcium phosphate, calcium sulfate, biodegradable polymeric materials, or combinations thereof.
A presently preferred composition comprises demineralized osteogenic bone powder in a carrier; the composition can be applied to a bone defect site to induce new bone growth. This composition of the present invention comprises demineralized bone particles or granules (referred to herein as “demineralized bone powder”) in an inert biocompatible carrier.
In a preferred embodiment, the particles/granules have a median length to median thickness ratio about 1.742:1, a mean length of 0.25-1 mm (250-1,000 microns) and a mean thickness of about 0.5 mm (500 microns).
The presently preferred biocompatible carrier of the composition of the invention is a material that confers reverse phase thermodynamic properties on the composition. The use of PLURONIC® F127 as a component of an osteointegration promoting composition is set forth in U.S. Pat. No. 5,503,558, issued Apr. 2, 1996 to the inventor herein, Cameron M. L. Clokie; and in PCT International Publication No. WO 95/13099. In a presently preferred embodiment, the carrier comprises a polymer marketed by BASF (Parsipanny, N.J.) as PLURONIC® F127. PLURONIC® F127 is a poly(oxyalkylene) blo
GenSci OrthoBiologics, Inc.
Hartley Michael G.
Howrey Simon Arnold & White , LLP
Willis Michael A.
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