CH680900A5 - - Google Patents

Description

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description

The invention relates to osteoinductive bone replacement material based on substances containing calcium phosphate, and to processes for the production thereof.

Characteristic of the known technical solutions

The effect of prostaglandins is described in many ways in the patent literature.

In general, prostaglandins (PG) are used for the medicinal treatment of inflammatory conditions (DE-3 404 209 A1), but also the derivatives and analogs derived from the PG for the treatment of arterial occlusive diseases (DE 3 631 169 A1), for the treatment of damage the liver, the pancreas and the kidney (DE-3 427 797 A1), for the treatment of cell damage to the digestive system, the liver and the pancreas (DE-3 318 571 A1). It is striking that there is apparently a greater focus on the therapeutic use of the PG of the E series. For example, PGs from the E series are used to expand the cervix (DE-3 307 816 A1), PGs Ei, E2 and E3 are used for cancer prophylaxis (EP-106 571), PGs E2 are used therapeutically for increasing eye pressure and for so-called. glaucoma (EP-93 390), PG egg has been proposed for the treatment of artery narrowing (arteriostenosis) (EP-97 481) etc.

Another series of examples deals with the combination with "pharmaceutically acceptable carriers" (EP-249 194). In this sense, PG adsorbates are to be mentioned, which are bound to pre-gelatinized starch (DE-304 880 A1), crospovidone (DE-3 304 867 A1) and dextrans (DE-3 304 864 A1).

On the other hand, e.g. Tricalcium phosphate (TCP) has been mentioned as a pharmacological deposit vehicle for gentamycin etc. (Vergi. EP-34 004). For the above Applications, i.e. in connection with PG, TCP does not appear to be suitable as a carrier material, e.g. It is known that when applied subcutaneously, TCP can cause irritation.

In bone tissue, on the other hand, the TCP or suitable modifications have been successfully used to correct bone defects and one can refer to the limited resorbability of this bone substitute material (EP-A 237 043). However, the scientific literature has often referred to the too long absorption times, i.e. a delayed reossification.

In the scientific literature on the use of PG, i.a. also pointed to an effect of prostaglandin E2 on the bone formation (Jee, WSS et al .: The ef-fects of PG E2 in growing rats: increased metaphyseal hard tissue and cortico-endosteal bone formation; Calcif. Tissue Int. Vol. 37 [ 1985] pp. 148-157). Areas of restricted and increased bone growth were identified in this work.

In US Pat. No. 4,621,100, treatment of osteoporosis disease with PG of the E series or with its derivatives is also proposed for the field of human medicine. The active ingredient is administered orally according to the claim of the invention. The described effect of the PG substances according to the examples is presented more or less as a systemic one, regarding the entire bone structure.

On the other hand, it is unknown how PG, for example, could advantageously be used to remedy medium-sized to large bone defects in the field of human medicine and how the application of the low doses in question for such applications is preferably concentrated on this defect area.

Aim of the invention

The aim of the invention is to overcome the disadvantages of the prior art described. Essence of the invention

The invention has for its object to develop a modified ceramic bone implant and a method for its production, which has a targeted osteoinductive effect, improves reossification and is suitable for filling bone defects of various sizes, so that it can be widely used in all areas of surgery .

This object is achieved by means of an osteoinductive bone replacement material according to the wording according to claim 1. According to the invention, surface-reactive (bioactive) materials which have OH groups and / or silane groups on their surface are treated with prostaglandins of the E series or stabilized prostaglandins of the E series. The binding with PG achieved via the OH groups leads to a delayed release by desorption after implantation in the organism of animals or humans. An even better binding and thus further delayed release can be achieved by silanizing a surface-reactive (bioactive) inorganic bone substitute material based on calcium phosphate-containing substances or, if this is not easily possible, after a pretreatment with bases suitable for these substances to apply these OH- Groups silanized. Prostaglandins of the E series or stabilized prostaglandins of the E series can then be coupled to this silane layer.

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This chemical coupling causes a delayed release. The deceleration rate is higher in every case than with pure surface adsorption.

Both resorbable materials, such as alpha and beta-tricalcium phosphate (TCP), derived surface-modified forms, which have a higher calcium release than the underlying body, as well as long-term stable bone substitute material are suitable as surface-reactive (bioactive) bone substitute material. Hydroxyapatite and corresponding glass ceramics as well as their surface-modified forms are considered as surface-reactive (bioactive), long-term stable implant material, the surface layer of which has a higher calcium release than the underlying body. In addition, the substances mentioned can also be used as an inorganic-organic composite, the organic material being a biocompatible polymer from the groups polyurethane, epoxy resin, monomer-free epoxidized polymeric hydrocarbon, polyhydroxybutyric acid, polylactates or polycarboxylic acid.

It is irrelevant whether the inorganic bone substitute material is connected to the PG of the E-series as a molded implant body or as granules. While the free surface for the adsorptive bond is fixed in the molded implant body, this is not the case when using a granulate for filling the bone defect. Therefore, in the latter case it makes sense to use a granulate treated with PG of the E series combined with an untreated granulate. This requirement of a combined application can e.g. occur in that when clearing a bone cyst, the amount necessary for filling is not known before the operation.

It is therefore necessary to limit the implant granules provided with PG of the E series to an amount that is guaranteed to be used for filling.

The content of the prostaglandin component will be in the range of approx. 2 to 6, preferably 3 to 4 milligrams of PG of the E series or its derivatives or converted stabilized forms of PG of the E series per patient, with a spontaneous release always below approx. 3 Should be milligrams.

Granules of, for example, different TCP phases or mixtures of TCP phases etc. are often used as resorbable bone substitute materials.

An increase in the silanization ability of these substances without OH groups on the surface is achieved by a specially developed treatment with a base that should be free of toxic accompanying components.

A special embodiment of the process according to the invention is characterized in that tricalcium phosphate shaped bodies or granules are first treated with a base containing OH components free of toxic accompanying components. This TCP material can consist of both the alpha-TCP phase and the beta-TCP phase, but also of mixtures of the two phases. This mixture in turn can be used within a ceramic structure as mechanically firmly connected, but it can also be formed by simply mixing the corresponding phase components. In addition, surface-modified TCP material is also suitable, such as a surface-treated alpha-TCP that has a higher calcium release than the underlying body (see DD 258 713).

The term granulate is used to refer to a particle mixture of particle sizes between 63 to 800 μm, preferably between 200 to 500 μm for use in the stomatological field and 200 to 800 μm for use in the orthopedic field.

In principle, all bases that are free of toxic accompanying components, such as NaOH, KOH, Ca (OH) 2, are suitable for the treatment with the base containing OH ions.

This choice of base has a certain influence on the result of the release of prostaglandins of the E series or stabilized prostaglandins of the E series and is also taken into account from the point of view of whether the presence of cations which form small amounts of the base is or is not detrimental to the intended use. The treatment with a base carrying OH ions is in principle carried out in corresponding aqueous solutions of pH values between approx. 7.5 and 9.5. With regard to the stability of prostaglandins of the E series or stabilized prostaglandins of the E series, the pH when loading the granules should not exceed 9.

The TCP-based bone replacement granules are introduced into this solution and heated to temperatures between 50 ° C. and the boiling point of the solution for about 30 to 300 minutes. The TCP material can be dried at a temperature between approx. 60 to 150 ° C (for 0.5 to 3 hours).

It has now surprisingly been found that TCP material pretreated in this way can also bind prostaglandin of the E series or stabilized prostaglandins of the E series in an adsorptive or chemical manner analogously to other surface-reactive (bioactive) carriers. It was also found that the release can be delayed further by silanization and subsequent coupling of prostaglandins of the E series or stabilized prostaglandins of the E series. It goes without saying that in this way the total amount of PG implanted can be higher than with untreated granules.

This enables a longer-lasting release of PG during implantations.

Silanization can be carried out using a large number of silanes of the general formula:

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ORI

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R2 0 - Si - <CH2) n-R4

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OR3

take place in which R 1, R 2 and R 3 can be identical or different and can represent alkyl radicals having 1 to 5 carbon atoms, preferably ethyl radicals; n is an integer from 1 to 5 and R4 is the

Group is -NH2, -COOH or -CH-CH-R5, where R5 is an alkyl radical having 1 to 5 carbon atoms

Can be 20 v or hydrogen.

The tests showed that PG often has a silane-specific ability to bind to bone substitute material. The silanes gamma-aminopropyltriethoxysilane and glycidoxypropyltriethoxysilane were preferably used.

25 The silanization is usually carried out with 1 to 10% silane solutions in an ethanol / water / HCl mixture in a mixing ratio between 40 to 60 to 60 to 40, preferably a 50% alcoholic HCL solution with a pH of 2 , 0 to approx. 4.5. The treatment time varies depending on the silane between about 30 minutes and 24 hours. The silanized bone substitute material is then rinsed several times with respect to the pH in a phosphate buffer or PBS solution under approximately physiological conditions. Alternatively, it can also be washed with an alcoholic solution and then the carrier material can be subjected to a drying process at 150-250 ° C.

If gamma-aminopropyltriethoxysilane is used, it can also be activated before treatment with the active ingredient. For this purpose, i.a. a 1 to 10% 35 glutardialdehyde solution, PBS solution being used as the solvent, or a 0.01 to 0.1 molar sodium potassium phosphate buffer solution. This activation is possible through a treatment of between 5 and 40 ° C for several hours, usually 24 hours. Then wash again. In the sense of the present description of the invention, the PG of the E series, their stabilized forms of the PG of the E series, which are coupled to this silanized layer, are used as prostaglandins. 40 In the preparation of the mixtures for the coupling between PG and the inorganic material, the procedure is that first the PG of the E series or stabilized forms of the PG of the E series, preferably PG Ei and PG E2, in water, PBS, be dissolved in a mixture consisting of 90% of a 150 millimolar TRIS buffer solution and 10% ethanol or in an unbuffered ethanol solution. Stabilized PGs are also particularly suitable, since chemical stabilization usually results in an improvement in water solubility.

The bone replacement materials are in a corresponding aqueous solution or in a 0.01 to 0.1 molar phosphate buffer solution (PBS) or in an alcoholic solution (approx. 10 to 50% ethanol) with a content of approx. 100 micrograms to Incubate 5 milligrams of PG per milliliter of solvent for about 15 to 300 minutes at room temperature. The pH value of these solutions can vary within the limits of 50 from approx. 4 to 8, but it makes sense to work under approximately physiological conditions or in the acidic range. The subsequent drying is carried out at about 37 ° C in a vacuum.

This PG E series chemically coupled to surface reactive (bioactive) bone substitute materials or stabilized products from PG E series results in implantation as a bone substitute material 55 significantly better than when only one of these substances is used, with the use of PG at the implantation site is hardly possible even without this procedure. On the other hand, the use of surface-reactive (bioactive) implant materials does not in itself result in such a good effect of osteoinduction. This surprising effect becomes particularly clear when using resorbable bone substitute material, because in addition to a greatly improved new bone formation - presumably due to the associated improvement in the supply situation of the peri-implant tissue - faster resorption was also observed as a pleasant and desirable side effect.

Especially for human use, it is absolutely necessary to adhere to the limit concentrations of PG, for example about 0.5 to 6 milligrams per implantation. For the purpose of the mentioned dilution, in particular in the treatment of large-lumen bone defects, but also

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To further delay the release, it is possible to coat the treated substances with an organic, biocompatible, resorbable (biodegradable) polymer. In principle, all of these polymers are suitable, with polyhydroxybutyric acid, gelatin, resorbable polyurethanes and polylactates appearing to be particularly suitable. This inevitably results in a further delay in the release of the prostagladins of the E series or their derivatives or stabilized prostagladins of the E series.

If a further delay in release is dispensed with, these substances can also be used as a combination in the form of simple particulate substance mixtures in order to achieve a quasi dilution of the granules treated with prostaglandin of the E series or their derivatives or stabilized prostaglandins of the E series. From this aspect of simple dilution, other resorbable organic materials are of course also suitable which Can not fulfill the intended purpose during the transfer, such as collagen. Investigations showed that the combined use of PG-provided TCP granules, with PG-free, surface-modified TCP and collagen led to the best results in defect filling.

The invention will be explained in more detail below by examples.

Execution examples

The process step of treating the calcium phosphate-containing support material with a base which contains OH ions and is largely free of toxic constituents is preferably carried out when it is a TCP product:

(a) Surface treatment with bases carrying OH ions

A) The carrier material is heated in an aqueous NaOH solution with pH = 8.0 at 90 ° C for 2 hours. The material is then dried at approx. 100 ° C for 120 minutes.

B) The carrier material is heated in an aqueous Ca (OH) 2 solution with pH = 8.4 at 80 ° C. for 3 hours. The subsequent treatment of the material is analogous to example A).

(b) silanization

I) The base material pretreated with a base is incubated with a 1% solution of gamma-aminopropyltriethoxysilane in ethanol / water solvent (1: 1) at 50 ° C. for 4 hours. After washing three times with 20 ml 0.1 m phosphate buffer solution, pH = 7.2, the support material was washed with a 2% glutardialdehyde solution in the above. Phosphate buffer solution mixed, incubated for a further 2 hours at 37 ° C. and washed again three times in phosphate buffer solution.

II) The base material pretreated with a base is incubated with a 1% solution of glycodoxypropyltriethoxysilane in ethanol / water solvent (1: 1) at 50 ° C. for 4 hours. After washing three times with 20 ml portions of a 0.1 m phosphate buffer solution, pH = 7.2, the support material was prepared for further coupling reactions.

(c) PG impregnation example 1:

2 grams of an alpha-TCP granulate with a grain size between 200 and 500 μm, which had been pretreated according to example B) with a base, were silanized according to example I, with an ethanolic PGEi solution which contained a total of 10 milligrams of PG egg , incubated for about 60 minutes and then dried at 37 ° C. in vacuo.

As a test model, 4-month-old Wistar rats were placed in the tibial metaphysis, each filled with 0.2 grams of the treated material. Animals that received untreated material were implanted as a control group. To determine the osteogenesis and the osteoinduction, the animals were sacrificed after 3 months and various histalogical examinations were carried out.

It was shown that new bone formation and, surprisingly, resorption had progressed furthest in the group that had received material treated with PGEi.

Example 2:

2 grams of shaped implants, consisting of a glass ceramic based on apatite and wollastonite, were silanized in accordance with Example II and then incubated for 60 minutes with 2.5 ml of an ethanolic solution containing 1 milligrams of PG egg (4 milligrams of PG egg per milliliter) . The treated material was dried and implanted as in Example 1. Here too, untreated implant material served as a comparison.

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It was also shown here that the formation of the bone composite had progressed significantly further in the case of the samples treated with PG.

Example 3:

2 grams of a beta-TCP granulate with a grain size between 100 and 300 μm according to example B) were treated with a base, silanized according to example II and treated according to example 2, but with PG E2, and analogous animal experiments were carried out.

As expected, a test result similar to Example 1 was also achieved here. The impression that the resorption was significantly increased by the combined application was confirmed, even higher than in comparison with samples in which PG had been added virtually physically mixed.

Example 4:

4 grams of a granulate, some of which consisted of TCP, were heated with an aqueous NaOH solution with pH = 7.8 at 90 ° C. for 2 hours. The material was then dried at approximately 100 ° C. for approximately 120 minutes. The granules were then incubated with 20 milligrams of a stabilized PG E2, which had been dissolved in a 50% strength ethanol / water solution, at 37 ° C. for 30 minutes and then dried in vacuo.

Animal experiments were carried out in accordance with Example 1, 0.3 gram of the treated granules being used per experimental animal.

Here, too, there was an improvement over the control group that received PG-free material.

Example 5:

A PG-treated alpha-TCP granulate, which was produced in accordance with Example 1, was mixed with the same amount of collagen.

Mini pigs of the mini lion type were used as experimental animals. Bone defects were set which were sufficient to accommodate 0.5 grams of the mixture.

Defects served as controls, which were filled in with PG-free TCP-collagen mixtures in an analogous manner. Here, too, it was shown that the combination with PG (PGE1) led to a significant improvement in osteoneogenesis.

Claims (28)

Claims 1. Osteoinductive bone substitute material based on calcium phosphate-containing substances, characterized in that it consists of a mixture of one or more bioactive calcium phosphate-containing material (s) with prostaglandin E bound to the surface of this material (s) and free prostaglandin E or untreated bioactive calcium phosphate-containing material exists, with the mixture components being coated or not. 2. Implant according to claim 1, characterized in that it consists of a mixture of one or more bioactive calcium phosphate-containing material (s) with prostaglandin E bound to the surface of this (these materials) and free prostaglandin E and organically resorbable biocompatible substances as a further mixture component . 3. Implant according to claim 1, characterized in that it consists of one or more calcium phosphate-containing material (ien) with prostaglandin E bound to the surface of this / these material (ien) and a covering. 4. Implant according to claim 1 or 2, characterized in that it consists of one or more calcium phosphate-containing material (ien) with prostaglandin E bound to the surface of this / these material (ien) and organically resorbable biocompatible substances. 5. Implant according to claim 2, characterized in that the covering is selected from the group consisting of polyhydroxybutyric acid, gelatin, polylactates, polyhydroxybutyric acid being preferred. 6. Implant according to one of claims 2 or 4, characterized in that the organic resorbable biocompatible material is present in a proportion of 1 to 40 parts by mass in%. 7. Implant according to one of claims 2 or 4, characterized in that the organically resorbable material is selected from the group consisting of collagen, lactates, resorbable polyurethanes, with collagen being preferred. 8. A method for producing an osteoinductive bone replacement material based on calcium phosphate-containing substances, according to one of claims 1 to 7, characterized in that a bioactive calcium phosphate-containing bone replacement material which has OH groups and / or silane groups on its surface with a prostaglandin (PG) the E series or a stabilized form 6 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 CH 680 900 A5 the PG of the E series treated thereof, the stabilized form of the prostaglandins, absorbates of PGE on pregelatinized starch, crospovidones or dextrans. 9. The method according to claim 8, characterized in that a bioactive calcium phosphate-containing bone substitute material, which has OH ions on its surface, with a PG of the E series according to claim 8 or a stabilized form of the PG of the E series according to claim 8 treated of it. 10. The method according to claim 8, characterized in that a bioactive calcium phosphate-containing bone substitute material which has OH ions and silane groups on its surface, with a PG of the E series according to claim 8 or a stabilized form of the PG of the E series treated of it. 11. The method according to any one of claims 8 to 10, characterized in that the OH ions on the surface of the bioactive material result from a treatment of the material with a base which is free of toxic accompanying components. 12. The method according to claim 11, characterized in that the base is calcium hydroxide, sodium hydroxide or potassium hydroxide, preferably calcium hydroxide. 13. The method according to claim 8, characterized in that a bioactive calcium phosphate-containing bone substitute material, which has silane groups on its surface, with a PG of the E series according to claim 8 or a stabilized form of the PG of the E series according to claim 8 thereof treated. 14. The method according to any one of claims 8, 10 or 13, characterized in that the silane groups from a treatment of the material with a biocompatible silane coupling agent of the general formula 0R1 R2 0 - Si - <CH2) n-R4 OR3 originate in which R1, R2 and R3, which may be the same or different, represent a lower alkyl radical having 1 to 5 carbon atoms, preferably ethyl; n is an integer from 1 to 5 and R4 is the Group is -NH2, -COOH or -CH-CH-R5, where R5 can be a lower alkyl radical having 1 to 5 carbon atoms. 15. The method according to claim 14, characterized in that the silane is selected from the group consisting of f-aminopropyltriethoxysilane, glycidoxypropyltriethoxysilane and / or mixtures thereof. 16. The method according to any one of claims 8 to 15, characterized in that the calcium phosphate-containing material is selected from the group consisting of a-tricalcium phosphate; β-tricalcium phosphate; Hydroxylapatite; Glass ceramics and their mixtures and surface-modified forms and is preferably tricalcium phosphate. 17. The method according to any one of claims 8 to 15, characterized in that the calcium-containing material is an inorganic-organic composite, the organic material being a biocompatible polyurethane, a monomer-free epoxidized polymeric hydrocarbon, a polyhydroxybutyric acid, a polylactate or a polycarboxylic acid. 18. The method according to claim 16, characterized in that the surface-modified substances have a higher calcium release than the underlying body. 19. The method according to any one of claims 8 to 18, characterized in that the calcium phosphate-containing material is particulate and absorbable. 20. The method according to claim 19, characterized in that the particulate calcium phosphate-containing materials are granules with a grain size in the range from 63 to 1000 μm, preferably in the range from 63 to 500 μm. 21. The method according to any one of claims 8 to 18, characterized in that the calcium phosphate-containing material is not absorbable. 7 5 10th 15 20th 25th 30th 35 40 45 50 55 CH 680 900 A5 22. The method according to any one of claims 8 to 21, characterized in that the prostaglandin E is selected from the group consisting of prostaglandin egg (PGEi) and / or prostaglandin Ez (PGE2) and stabilized forms of PGE1 or PGE2. 23. The method according to claim 14 or 15, characterized in that the silanized material is activated before the PG treatment, preferably by treatment with a glutardialdehyde solution for several hours. 24. The method according to any one of claims 8 to 23, characterized in that the product treated with prostaglandin E is surrounded with biocompatible coating materials. 25. The method according to claim 24, characterized in that the coating material is selected from the group consisting of polyhydroxybutyric acid, gelatin, polylactates, polyhydroxybutyric acid being preferred. 26. The method according to any one of claims 8 to 23, characterized in that the product treated with prostaglandin E is mixed with biocompatible organic absorbable substances. 27. The method according to claim 26, characterized in that the organic resorbable substance is selected from the group consisting of collagen, lactates, resorbable polyurethanes, with collagen being preferred. 28. The method according to claim 8 to 27, characterized in that the PG-treated material is mixed with untreated material. 8th