Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Carbohydrate doai
Patent
1995-08-30
1999-04-13
Fonda, Kathleen K.
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Carbohydrate doai
514 54, 514 56, 514 59, 623 11, 623 16, A61K 31715, A61K 3173, A61K 31725, A61F 202
Patent
active
058940707
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA
The present invention relates to new techniques for stimulating or accelerating regeneration of hard tissue in connection with so called osseointegration, for example the effect sought in the implantation of foreign implants in hard tissue, particularly bone tissue. The invention also relates to a process for carrying out such osseointegration while applying the new techniques according to the invention. Furthermore, the invention relates to the generation of new bone in relation to bone tissue defects or otherwise need of bone tissue.
BACKGROUND OF THE INVENTION
Implants intended for anchorage in hard tissue, particularly bone tissue, have enjoyed an ever increasing use in odontology, orthopedics, neurosurgery, hand surgery and plastic and reconstructive surgery. Long term anchorage of implants in bone has been achieved with titanium, and it can be assumed that titanium-based materials also in the future will be used to a large extent as the material of choice for implants and prosthesis.
A clinical problem when dealing with so called osseointegration is the fact that the implant cannot be subjected to a load before sufficient bone anhorage has been achieved, which may require as much as 6 to 9 months. It is therefore clinically of utmost importance to accelerate the healing process by providing stimulated bone formation in association with the implants. There is also a need to regenerate bone in order to bridge defects or sections where bone resorption has taken place in for example toothless parts of jaws or where bone tissue has been lost due to e.g. trauma, tumor or surgery.
SUMMARY OF THE INVENTION
The main object of the present invention is to stimulate growth of cells in hard tissue, for example bone cells, so that the hard tissue volume will increase.
Another object of the invention is to provide means resulting in the formation of regenerated bone tissue of dominantly lamellar, compact type, whereas the extent of formation of scar tissue will be minimized.
Yet an object of the invention is to provide a new agent capable of providing in connection with implants in hard tissue stimulated regeneration of hard tissue, for example bone tissue.
Another object of the invention is to provide a process for improved osseointegration in connection with implantation of foreign implants in hard tissue while stimulating regeneration of tissue.
Another object of the invention is to provide implants treated with an agent stimulating regeneration of hard tissue.
For these and other objects which will be clear from the following disclosure there is provided through the invention a new use of chitosan and a polysaccharide immobilized thereto selected from heparin, heparan sulphate, chondroitin-sulphates and dextran sulphate. This new use relates to the manufacture of an agent capable of providing stimulated regeneration of hard tissue. Such stimulated regeneration may for example be provided in connection with implants in hard tissue, such as bone tissue.
The polysaccharide can be immobilized to the chitosan matrix in several ways, for example by ionic bonds, by covalent binding either multipoint or endpoint binding, or by mechanical fixation in the chitosan matrix in connection with precipitation of the chitosan from solution. Ionic bonds and covalent bonds are preferred immobilization forms.
The hard tissue stimulating agent according to the invention may be present in different physical forms, for example as a membrane, a powder, a gel, beads or a solution. In the case where an implant is intended, that part of the implant which is to be integrated in hard tissue can be dipped for application of the agent onto the implant. The agent can, of course, also be supplied to the hard tissue per se, for example in a cavity provided in bone tissue.
The material preferred for the implantation is titanium but other implant materials may as well be used.
Chitosan is a linear 1,4-bound polysaccharide built up from .beta.-D-glucose amine units. The chitosan is manufactured by N-deacetylation of chitin, a
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Hammar et al. Chitin Chitosan, Proceeding Int. Conf., 2nd 1982, 213-215.
Kawakami et al. Biomaterials 1992, 13, 759-763.
Borah et al. In "Advances in Chitin and Chitosan", Brine et al., eds., Elsevier (Netherlands) 1992, 47-53.
R.A.A. Muzzarelli et al. Osteoconductive properties of methylpyorolidinone chitosan . . . Biomaterials 14:928 (1993).
L.P. Nilsson "Effects of Hyperbaric Oxygen . . . " Swedish dental journal/Suppl. 64: 19-25 (1989).
Hansson Hans-Arne
Johansson-Ruden Gunilla
Larm Olle
Astra Aktiebolag
Fonda Kathleen K.
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