DD285240A7 - METHOD FOR PRODUCING AN OSTEOINDUCTIVE BONE REPLACEMENT MATERIAL - Google Patents

Abstract

The invention relates to a method for producing an osteoinductive bone replacement material for repairing bone defects, Aufbauplastiken etc. in the field of surgery, Orthopaedie u. Stomatology and the material itself. The object of the invention is to develop a modified ceramic bone implant and a production method therefor, which has a targeted osteoinductive effect, improves the reossification and is suitable for repairing bone defects. According to the invention, a bioactive calcium phosphate containing bone substitute material having on its surface OH groups and / or silane groups is treated with an E series prostaglandin (PG) or its derivatives or a stabilized form of the PG or E series or mixtures thereof. The implant is characterized in that it consists of calcium phosphate-containing materials with surface-bound prostaglandin E and / or its derivatives and a coating. {Bone substitute material, osteoinductive, calcium phosphate-containing; prostaglandin; Glass ceramics; Implant, bioactive}

Description

Field of application of the invention

The invention relates to a method of producing an osteoinductive bone substitute material for repairing bone defects, structural elastics, etc. in the field of all surgical disciplines, including orthopedics, traumatology and stomatology, as well as the material itself.

Characteristic of the known technical solutions

The effect of prostaglandins is widely described in the patent literature.

In general, prostaglandins (PG) are used for the medicinal treatment of inflammatory conditions (DE-3404209 A1),

but also derived from the PG derivatives and analogs for the treatment of arterial occlusive diseases (DE 3631169 A1), for the treatment of damage to the liver, pancreas and kidney (DE-3427797 A1), for the treatment of cell damage of the Digestive system, the liver and the pancreas (DE-3318571 A1) called.

Remarkably, it seems that there has been a greater emphasis on the therapeutic use of PG series PG.

For example, PG will be the e-series «? used for enlargement of the cervix (DE-3307816 A1), Pu E ₁ , E ₂ and E ₃ are used for cancer prevention (EP-106571), PG E ₂ is used therapeutically in increasing the eye pressure and the so-called. Green Star (Glaucoma) ( EP-93390), PG E, has been used for the treatment of arterial stenosis (arteriostenosis) (EP

97481), etc.

Another series of examples relates to the combination with "pharmaceutically accepted carriers" (EP-249194).

In this sense, adsorbates of PG are mentioned, which are bound to pregelatinized starch (DE-304880 A1), crospovidone (DE-3304876 A1) and dextrans (DE-3304864 \ 1).

On the other hand, z. For example, tricalcium phosphate (TCP) has been cited as a pharmaceutical antagonist for gentamycin, etc. (see EP-34004).

For r o o. Applications, d. H. in connection with PG, TCP does not appear to be suitable as a carrier material, since z. For example, it is known that TCP administered subcutaneously may cause irritation.

In bone tissue, on the other hand, the TCP or appropriate modifications have been successfully used for bone defect repair, and it is possible to refer to the limited absorbability of this bone replacement material (EP-A-237043). However, it has often been pointed out in the scientific literature on the too long absorption times, d. H. a delayed reossification.

In the scientific literature on the use of PG has recently been, inter alia, on a bone formation-influencing effect of prostaglandin E ₂ pointed (Jee, WSS et al .: The effects of PG E ₂ in growing rats: increased metaphyseal hard tissue and cortico- Endosteal bone formation; Calcif.Tissue Int.Vol. 37 (1985) pp. 148-157). In this work areas of restricted and enhanced bone growth were detected.

In US-P 4621100 a treatment of osteoporosis disease with PG of the Ε series or with their derivatives is also proposed for the field of human medicine. The Wirks'oifzuführung takes place according to the invention claim orally. The described effect of the PG substances according to the examples is more or less represented as systemic concerning the entire bone structure.

The introduction of broadband microbicides in general is already described in EP 58867 and EP 61108. In this case, a KnochenimplanU t from TCP ceramic with microporous or macroporous structure is soaked with a drug and then with a r. coated polymeric biodegradable coating. In both patents, drug release is determined by the rate of diffusion of the drugs through the polymeric coating. On the ceramic base, the bond is only unspecific and limited. A disadvantage is the additional application of a polymeric substance that must be biocompatible and its absorbability must be ensured, otherwise the polymer capsule would have to be reintegrated. In addition to the precise control of the layer thickness of the polymer brings this

additional Prou 3 in the implantation of drug-bearing bone substitutes with it.

On the other hand, it is unknown how PG could be used, for example, advantageously for the remedy of medium 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.

Object of the invention

It is the object of the invention to overcome the described disadvantages of the prior art.

Essence of the invention

The invention has for its object to develop a modified ceramic bone implant and a method for its production, which acts specifically osteoinductive, improves the reification and is suitable for filling bone defects of various sizes, which it can find wide application in all areas of surgery , According to the invention, surface-reactive (bioactive) materials which have OH groups and / or silane groups on their surface are treated with prostaglandin in the Ε series or its derivatives or stabilized prostaglandins of the Ε series. The binding with PG achieved via the OH groups leads to a delayed release by desorption after implantation into the organism of animals or humans.

An even better binding and thus further delayed release is achieved by silanizing a surface-reactive (bioactive) inorganic bone substitute material based on calcium phosphate-containing substances or, if this is not readily possible, by pretreatment with bases suitable for these substances for applying this OH. Silanized groups. Then, Pro series prostaglandins or their derivatives or stabilized stag series prostaglandins can be coupled to this silane layer.

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

As a surface-reactive (bioactive) bone substitute material offer both absorbable materials, such as alpha and beta tricalcium phosphate (TCP), derived surface-modified forms, which have a higher Calciumfrüisetzjiig than the underlying body as well as long-term stable bone substitute material. As a surface-reactive (bioactive), long-term stable implant material hydroxyapatite and corresponding glass ceramics and their surface-modified forms are considered, the surface layer has a higher calcium release than the underlying body. In addition, the substances mentioned can also be used as an inorganic-organic composite

wherein the organic material is a biocompatible polymer selected from the group consisting of polyurethane, epoxy resin, monomer-free epoxidized polymeric hydrocarbon, polyhydroxybutyric acid, polylactates or polycarboxylic acid. It does not matter whether the inorganic bone substitute material is brought into contact with the der-series PG or its derivatives as an implant molding or as granules. While the implant shaped body has the free surface for adsorptive binding, this is not the case with the use of granules for bone defect filling. Therefore, in the latter case, it is useful to use a granule treated with PG of the Ε series or deron derivatives combined with untreated granules. This compulsion of a combined application can, for. B. occur in that when clearing a bone cyst, the amount necessary for filling before the operation is not established. Therefore, it is necessary to limit the implant granules provided with der-series PG or its derivatives to an amount which is guaranteed to be used for replenishment.

The content of the prostaglandin component will be in the range of about 2 to 6, preferably 3 to 4 milligrams of the Ε-series PG or derivatives thereof or equivalently stabilized forms of the der-series PG per patient, with spontaneous release always below about 3 milligrams should.

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

An increase in the silanizing ability of these surface OH-free substances is achieved by a specially developed treatment with a base which should be free of toxic accompanying components A particular embodiment of the process according to the invention is characterized in that tricalcium phosphate shaped bodies or granules are first treated with an OH ~ -ion-bearing base free of toxic accompanying components.This TCP material can consist of both the alpha-TCH phase and the beta-TCP phase, but also of mixtures of both phases. This mixture, in turn, can be trapped within a ceramic structure as mechanically fixed for use, but it can also be formed by simply mixing appropriate phase fractions., In addition, surface-modified TCP material, such as a surface-treated alpha-TCP, is also suitable Cal ciumfreisetzung than the underlying body has (see DD 258713).

The term granulate combines a particle mixture of the grain ranges between 63 to 800 micrometers, preferably between 200 to 500 micrometers for use in the dental field and 200 to 800 micrometers for use in the orthopedic field.

For the treatment with the OH'-ion-bearing base, in principle all bases are suitable which are free of toxic accompanying components, such as, inter alia, NaOH, KOH, Ca (OH) ₂ . This choice of base has a determining influence on the result of the release of Ε-series prostaglandins or their derivatives or stabilized prostaglandin E-series and is further taken from the point whether the presence of - in itself small amounts - to the Base forming cations the intended use is detrimental or not. The treatment with an OH.sup.- -ion-bearing base takes place in principle in corresponding aqueous solutions of the pH values between about 7.5 and 9.5. In view of the stability of Pro-series prostaglandins or their derivatives or stabilized stag-series prostaglandins, the ph should not exceed 9 when loading the granules. The TCP-based bone substitute granule is placed in this solution and heated to temperatures between 50 ° C and the boiling point of the solution for about 30 to 300 minutes. A drying of the TCP material can be carried out at a temperature between about 60 to 15O ⁰ C (0.5 to 3 hours long). It has now surprisingly been found that pretreated in this way TCP material analogous to other surface-reactive (bioactive) carriers also prostaglandin Ε series or their derivatives or stabilized prostaglandins of the E series adsorptive or chemically bind. Furthermore, it has been found that silanization and subsequent coupling of prostaglandins of the E series or their derivatives or stabilized prostaglandins of the E series, the release can be delayed even further. It is understood that in this way the total amount of PG implanted may be higher than that of untreated granules. This allows longer-lasting release of PG during implantation. The silanization can be achieved by a jet of silanes of the general formula:

OR ¹ IR ^ O-Si- (CH.:) ,, - R "

OR- ¹

where R ¹ , R ² and R ^{3 may be the} same or different, and may be alkyl radicals of 1 to 5 carbon atoms, preferably ethyl radicals; η is an integer from 1 to 5 and R ^{4 is} the group -NH ₂ , -COOH or - £ (- {- CH- ⁶

wot ji R ^{5 can be} an alkyl radical having 1 to 5 carbon atoms or hydrogen.

The experiments showed that there is often a silane-specific binding ability of PG on the bone replacement material.

Preferably, the <3 silanes were gamma-aminopropyltriethoxysilane and glycidoxypropyltriethoxysilane.

The silanization is generally carried out with 1 to 10% silane solutions in an ethanol / water / HCl mixture in a mixing ratio of 40:60 to 60:40, preferably a 50% strength alcoholic HCl solution with a pH of 2, 0 to about 4.5. The duration of treatment varies between about 30 minutes and 24 hours, depending on the silane.

Thereafter, the silanized bone substitute material in a phosphate buffer or PBS solution under approx

physiological conditions with respect to the pH rinsed several times. Optionally, it is also possible to wash with an alcoholic solution and then subject the support material to a drying process at 15-250 ° C. When using the gamma-aminopropyltriethoxysilane, activation may additionally be carried out before treatment with dom active substance. For this purpose u. a. a 1 to 10% glutaric dialdehyde solution, using as solvent PBS solution or a 0.01 to 0.1 molar sodium-potassium phosphate buffer solution. This activation is possible by a treatment of between 5 and 40 ° C for several hours, usually for 24 hours. Thereafter, it is washed again. For the purposes of the present invention description, prostaglandins are the PGs of the Ε series, their stabilized forms or derivatives of the PG series, which are coupled to this silanized layer.

In the preparation of the mixtures for the coupling between PG and the inorganic material is carried out so that first the PG series or their derivatives or stabilized forms of the PG series, series, preferably PG E) and PG E ₂ , in Water, PBS, in a mixture consisting of 90% of a 150 millimolar TRIS buffer solution and 10% ethanol or dissolved in an unbuffered ethanol solution. Also, so-called stabilized PG are particularly suitable since chemical stabilization usually results in an improvement in water solubility.

The bone replacement materials are dissolved in an appropriate aqueous solution or in a 0.01 to 0.1 molar of phosphate buffer solution (PBS) or in an alcoholic solution (about 10 to 50% ethanol) containing about 100 micrograms to 5 Milligrams of PG per milliliter of solvent for about 15 to 300 minutes incubated at room temperature, the pH of these solutions may vary within the limits of about 4 to 8, but it is useful 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 chemically coupled to surface-reactive (bioactive) bone substitute materials PG Ε series or derivatives thereof or stabilized products of PG Ε series results in implantation as a bone substitute material significantly better results than when using only one of these substances, the use of PG at the implantation site even without this method is hardly possible. On the other hand, the use of the surface-reactive (bioactive) implant materials alone does not give such a good effect of osteoinduction either. This surprising effect becomes particularly clear with the use of resorbable bone substitute material, since, in addition to a greatly improved formation of new bone - presumably due to the concomitant improvement in the layering of the peri-implant tissue - a faster absorption could also be observed as a pleasant and desirable concomitant.

Especially for human use, it is necessary to strictly 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-sized bone defects, but also to further delay the release, it is possible to coat the treated substances with an organic, biocompatible, resorbable (biodegradable) polymer. From the group of these polymers are in principle all, with polyhydroxibutyric acid, gelatin, resorbable polyurethanes and polylactates seem particularly suitable. This inevitably results in a further delay in the release of Prostglandins of the E series or their derivatives or stabilized prostaglandins of the E series.

Abandoning further delay in release, these agents may also be used as a combination in the form of simple particulate mixtures to achieve quasi-dilution of granules treated with E series prostaglandin or its derivatives or stabilized E series prostaglandins. From this aspect of simple dilution, of course, other resorbable organic materials are also suitable, the above mentioned. Intended to serve in the enclosure, such as collagen. Investigations have shown that the combined use of PG-containing TCP granules, PG-free, surface-modified TCP and collagen led to the most favorable results in defect filling

 The invention will be explained in more detail by examples.

embodiments

The process step of treating the calcium phosphate-containing support material with an OH.sup.- -ion-bearing base, which is largely free of toxic constituents, is preferably carried out if it is a TCP product:

(a) Surface treatment with OH.sup. + ion-bearing bases

A). The support material is heated in an aqueous NaOH solution with pH = 8.0 at 90 ^° C. for 2 hours. Subsequently, the material is dried at about 100 ^° C. for 120 minutes.

B) The support material is heated in an aqueous C i (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 substrate 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 of 0.1 M phosphate buffer solution, pH = 7.2, the support material was mixed with a 2% glutaraldehyde solution in the phosphate buffer solution mentioned above, for 2 more hours at 37 ° C. incubated and washed again three times in phosphate buffer solution.

II) The pretreated with a base carrier material with a 1% solution of glycidoxypropyltriethoxysilane in ethanol / water solvent (1: 1 incubated) at 5O ⁰ C for 4 hours. After washing three times with 20 ml 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. ^c .s , 2 grams of alpIia-TCP granulate of grain size between 200 to 500 microns pre-treated with a base according to Example B) was silanized according to Example I with an ethanolic PGE _t solution totaling 10 milligrams PG egg contained, incubated for about 60 minutes and then dried at 37 ° C in vacuo.

As a trial model, 4-month-old Wistar rats were found to have defects in the tibial metaphysis, which were filled with 0.2 gram each of the treated material. As a control group, animals were selected which received untreated material. For the determination of oestogenesis and osteoinduction, animals were killed after 3 months and various histological examinations were carried out.

It was found that the bone regeneration, and surprisingly also the absorption, was most advanced in the group implanted with PGEi-treated material.

Example 2: 2 g implant tablets consisting of a glass ceramic based on apatite and wollastonite according to Example II were silanized and then incubated with 2.5 ml of an ethanolic solution for 60 minutes, containing 1 mg PG E _t (4 mg PG egg per milliliter). The treated material was dried and implanted analogously to Example 1. Again, untreated implant material served as a comparison.

It was also shown here that bone formation in the case of the PG-treated samples was significantly more advanced.

Example 3: 2 grams of a beta-TCP granulate of particle size between 100 and 300 micrometers according to Example B) were treated with a base, silanized according to Example II and treated according to Example 2, but with PG E ₂ , and carried out analogous animal experiments.

As expected, an analogous test result to Example 1 was also achieved here. It confirms? The impression that the absorption was significantly increased by the combined application was even higher than in comparison to samples in which PG had been added physically mixed.

Example 4: 4 grams of granules consisting in part of TCP were heated with 9O ⁰ C aqueous NaOH solution at pH 7,8 for 2 hours. Subsequently, the material was dried at about 100 ^° C. for about 120 minutes, for a long time. Then, the granules were incubated with 20 milligrams of a stabilized PG E _{2 dissolved} in a 50% ethanol / water solution at 37 ° C for 30 minutes and then dried in vacuo.

Animal experiments were carried out according to Example 1, wherein in each case 0.3 grams of the treated granules per laboratory animal were used.

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

Example 5: A PG-treated alpha-TCP granule prepared according to Example 1 was mixed with the same amount of collagen.

As experimental animals mini pigs of the type Minilewe were used. Bone defects were sized that were sufficient to accommodate 0.5 grams of the mixture each.

As a control served defects that were filled with PG-free TCP-collagen mixtures in an analogous manner. Again, it was shown that the combination with PG (PGE ₍ ) led to a significant improvement in osteoneogenesis.

Claims (27)

1. A process for the preparation of an osteoinductive bone substitute material based calciumphosphathaltiger substances, characterized in that comprising a bioactive calcium phosphate-containing bone substitute material having on its surface OH groups and / or silane groups, with a prostaglandin (PG) of the Ε-series or derivatives thereof or a stabilized form of the der-series PG or mixtures thereof. 2. The method according to claim 1, characterized in that one comprises a bioactive calcium phosphate-containing bone substitute material having on its surface OH ~ ions, with a PG of the Ε-series or derivatives thereof or a stabilized form of the PG of the E series or mixtures thereof treated. 3. The method according to claim 1, characterized in that one comprises a bioactive calcium phosphate-containing bone substitute material having on its surface OhT-ions and silane groups, with a PG of the Ε-series or derivatives thereof or a stabilized form of the PG of the Ε-series or mixtures treated by it. 4. The method according to any one of claims 1 to 3, characterized in that the O 'Γ ions on the surface of the bioactive material from a treatment of the material with a base, which is free of toxic accompanying components originate. 5. The method according to claim 4, characterized in that the base is calcium hydroxide, sodium hydroxide or potassium hydroxide, preferably calcium hydroxide. 6. The method according to claim 1, dadut, characterized in that one treats a bioactive calcium phosphate-containing bone substitute material having on its surface silane groups with a PG of the Ε-series or its derivatives or a stabilized form of the PG of the Ε-series or mixtures thereof. 7. The method according to any one of claims 1,3 or 6, characterized in that the Silangruppsn from a treatment of the material with a biocompatible silane coupling agent of the general formula OR ¹ ρ '4 R ² O - Si - ( ^CH ₂ ) _n " ^R 0R ^J wherein R ¹ , R ² and R ³ , which may be the same or different, are a lower alkyl group having 1 to 5 carbon atoms, preferably ethyl; η is an integer from 1 to 5 and R ^{4 is} the group -NH ₂ , -COOH or _ _u _ _{u D} 5, wherein R ^{5 is} a lower alkyl radical having 1 to 5 carbon atoms can be. 8. The method according to claim 7, characterized in that the silane is selected from the group consisting of gamma- • Aminopropyltriethoxysilan, glycidoxypropyltriethoxysilane and / or mixtures thereof. 9. The method of claim 1 to 8, characterized in that the calcium phosphate-containing material is selected from the group consisting of alpha-tricalcium phosphate; beta-tricalcium phosphate; hydroxyapatite; Glass ceramics and mixtures thereof and surface-modified forms and is preferably tricalcium phosphate. 10. The method of claim 1 to 8, characterized in that the calcium-containing material is an inorganic-organic composite, wherein the organic material is a biocompatible polyurethane, a monomer-free epoxidized polymeric hydrocarbon, a polyhydroxybutyric acid, a polylactate or a polycarboxylic acid. 11. The method according to claim 9, characterized in that the surface-modified substances have a higher calcium release than the underlying body. 12. The method according to claim 1 to 11, characterized in that the calcium phosphate-containing material is particulate and absorbable. 13. The method according to claim 12, characterized in that the particulate calcium phosphate-containing materials are granules having a particle size in the range of 63 to 1000 micrometers, preferably in the range of 63 to 500 micrometers. 14. The method according to claim 1 to 11, characterized in that the calcium phosphate-containing material is not resorbable. 15. The method according to one or more of claims 1 to 14, characterized in that the prostaglandin E is selected from the group consisting of prostaglandin E ₁ (PGE ₁ ), prostaglandin E2 (PGE ₂ ) and derivatives of PGE ₁ or PGE ₂ and stabilized forms of PGE ₁ or PGE ₂ exists. A method according to claim 7 or 8, characterized in that the silanized material is activated prior to PG treatment, preferably by treatment with a glutaric dialdehyde solution for several hours. 17. The method according to claim 1 to 16, characterized in that surrounding the treated with prostaglandin E product with biocompatible wrapping materials. 18. The method according to claim 17, characterized in that the wrapping material is selected from the polyhydroxybutyrate, gelatin, polylactate, wherein polyhydroxybutyric acid is preferred. 19. The method according to claim 1 to 16, characterized in that mixing the treated with prostaglandin E product with biocompatible organic resorbable substances. 20. The method according to claim 19, characterized in that the organic resorbable material is selected from the group consisting of collagen, lactates, resorbable polyurethanes, with collagen being preferred. 21. The method according to one or more of claims 1 to 20, characterized in that the PG-treated material is mixed with untreated material. 22. The method according to claim 1, characterized in that a mixture of a) one or more bioactive calcium phosphate containing materials having attached to the surface of these materials prostaglandin E and / or its derivatives as well as b) free prostaglandin E and / or its derivatives or untreated bioactive calcium phosphate-containing materials, where the mixture components may optionally be coated, or organic resorbable biocompatible substances are prepared as further constituents. 23. The method according to claim 22, characterized in that one or more calcium phosphate-containing material / ien attached to the surface of prostaglandin E and / or its derivatives and is then provided with an envelope / will be. 24. The method according to claim 22, characterized in that one or more calcium phosphate-containing material / ien attached to the surface prostaglandin E and / or its derivatives and organic absorbable substances are added. 25. The method according to claim 22 or 23, characterized in that the calcium phosphate-containing materials are coated with preferably polyhydroxybuttoric acid, with gelatin and / or Polylaktate. 26. The method according to claim 22 or 24, characterized in that the calcium phosphate-containing materials, the organic absorbable material in a proportion of 1 to 40 parts by mass in% is added. 27. The method according to claim 22, 24 or 26, characterized in that as an organic resorbable material preferably collagen or lactates and resorbable polyurethanes is added.