DE3925185A1 - Osteo-inductive bone substitute material prodn. based on calcium phos - by treating bio-active material with prostaglandin of E series or deriv. - Google Patents

Abstract

In the prodn. of osteo-inductive bone substitute material (I) based on substances (II) contg. Ca phosphate, the novelty is that a bio-active bone replacement material (III) contg. (II), which has OH and/or silane gps. on its surface, is treated with prostaglandin of the E series (PGE) or its derivs. and/or a stabilised form of PGE. The OH ions on the surface of (III) are obtd. by treatment with a base free from toxic components, pref. NaOH, KOH or esp. Ca(OH)2. (III) with silane gps. are obtd. by treatment with a biocompatible silane coupling agent of formula R1O-Si(OR2)(OR3)-(CH2)n-R4 (IV), R1-3 independently are 1-5C alkyl, pref. Et, n is 1-5, R4 is -NH2, -COOH or -CH(O)-CH-R5, R5 is 1-5C alkyl, pref. gamma-aminopropyltriethoxysilane and/or glycidoxypropyltriethoxysilane. (II) is alpha- or beta-Ca3(PO4)2 (TCP), hydroxyapatite, glass ceramics and their mixts. and surface-modified forms, pref. TCP or an inorganic-organic composite, in which the organic material is a biocompatible polyurethane, monomer-free epoxidised polymeric hydrocarbon, polyhydroxybutyric acid, polylactate or polycarboxylate. (I) releases more Ca than (III). (II) pref. is particulate and resorbable, pref. with a particle size of 63-1000 esp. 63-500 microns or not resorbable. The prostaglandin pref. is PGE1, PGE2 or their derivs. or stabilised forms. Silanised (III) is activated, pref. by treatment with a glutardialdehyde soln. for several hrs., before treatment with PG. The prod. treated with PGE is given a biocompatible coating esp. polyhydroxybutyric acid and/or mixed with biocompatible resorbable organic materials (1-40 wt.%) pref. lactates, polyurethane or esp. collagen, untreated material and/or free PGE and/or its derivs. USE/ADVANTAGE - (I) is useful for correcting bone defects etc. in all surgical disciplines, including orthopaedics, traumatology and stomatology. The modified ceramic bone implantate improves reossification and filling of bone defects

Description

Field of application of the invention

The invention relates to manufacturing methods of an osteoinductive Bone replacement material for the elimination of Bone defects, building plastics etc. in the area of all surgical disciplines, including that of Orthopedics, traumatology and stomatology as well as the thus manufactured material itself.

Characteristic of the known technical solutions

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

In general, prostaglandins (PG) become medicinal Treatment of inflammatory conditions (DE 34 04 209 A1), however also the derivatives and analogues derived from the PG Treatment of arterial occlusive diseases (DE 36 31 169 A1), to treat the damage to the liver, the Pancreas and the kidney (DE 34 27 797 A1), for Treatment of cell damage to the digestive system Liver and the pancreas (DE 33 18 571 A1) called.

It is striking that apparently there is a stronger focus on therapeutic use of the PG of the E series. For example, PGs of the E series are used to expand the Cervix used (DE 33 07 816 A1), PG E₁, E₂ and E₃ are used for cancer prophylaxis (EP 1 06 571), PG E₂ finds therapeutic use for increasing eye pressure and in the so-called glaucoma (Glaucoma) (EP 93 390), PG E₁ was used Treatment of artery narrowing (arteriostenosis) (EP 97 481) suggested etc.  

Another series of examples is based on the combination with "pharmaceutically acceptable carriers" (EP 2 49 194) a. In this sense, adsorbates from PG are to be mentioned that to pregelatinized starch (DE 3 04 880 A1), crospovidone (DE 33 04 867 A1) and dextrans (DE 33 04 864 A1) are bound.

On the other hand, e.g. B. tricalcium phosphate (TCP) as Pharmacadepotträger for Gentamyzin etc. have been called (see EP 34 004). For the above Applications, d. H. in connection with PG, TCP does not appear as a carrier material suitable because z. B. it is known that TCP is subcutaneous applied can cause irritation.

In bone tissue, on the other hand, they are TCP or suitable Modifications with successful bone defect repair been applied and you can access the limited Reference absorbability of this bone replacement material (EP-A 2 37 043). However, in the scientific literature on this too long Absorption times indicated, d. H. delayed resossification.

In the scientific literature on the application of PG lately u. a. also on a bone formation influencing effect of prostaglandin E₂ noted (Jee, W. S. S. et al .: The effects of PG E₂ 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 have been restricted and increased bone growth.

In US-P 46 21 100 a treatment of osteoporosis disease with PG of the E series or with their derivatives too proposed for the field of human medicine. The Active ingredient delivery takes place according to the invention claim orally. The described effect of the PG substances accordingly the examples is more or less than systemic concerning the entire bone structure.

On the other hand, it is unknown how PG, for example, is advantageous for the repair of medium to large bone defects in the  Field of human medicine could be used and how one applies the low doses in question for such applications preferably on these Defect area concentrated.

Aim of the invention

It is the aim of the invention, the disadvantages described to overcome the state of the art.

Essence of the invention

The invention has for its object a modified ceramic bone implant and a method for its To develop manufacturing that has a targeted osteoinductive effect, improves reossification and for filling bone defects of different sizes is suitable, whereby it is widely used in all areas of surgery can.

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 their derivatives or stabilized prostaglandins of the E series. The binding with PG achieved via the OH ^- groups leads to a delayed release due to 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 substances containing calcium phosphate or, if this is not readily possible, after a pretreatment with bases suitable for these substances to apply these OH ^- Groups silanized. Prostaglandins of the E series or their derivatives or stabilized prostaglandins of the E series can then be coupled to this silane layer.

This chemical coupling causes a delay Release. The delay rate is in any case higher than with pure surface adsorption.

As a surface-reactive (bioactive) bone replacement material offers both absorbable materials, such as alpha and beta-tricalcium phosphate (TCP), derived therefrom surface-modified shapes that have a higher Calcium release as the underlying body have as well as long-term stable bone replacement material at. As a surface-reactive (bioactive), long-term stable Implant material will be hydroxyapatite and corresponding Glass ceramics and their surface-modified shapes viewed, the surface layer of which is higher Calcium release as the underlying body having. 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, Is polylactate or polycarboxylic acid.

It does not matter whether the inorganic bone substitute material as a shaped implant or as a granulate with the PG of the E series or their derivatives brought. While with the molded implant body the free Surface for the adsorptive bond is fixed, this is when using granules to fill bone defects not the case. Therefore, in the latter case, it makes sense to use a Granules treated with E series PG or its derivatives to be used in combination with untreated granules. This requirement of a combined application can e.g. B. thereby occur that when clearing a bone cyst the Filling necessary amount before the operation is not certain. It is therefore necessary to use the E series PG or its Derivatives provided implant granules to a lot  limit that are guaranteed to be used for replenishment got to.

The content of the prostaglandin component is in the range of about 2 to 6, preferably 3 to 4 milligrams PG of the E series or their derivatives or converted stabilized forms the PG of the E series are per patient, with a spontaneous Release should always be below about 3 milligrams.

Granules from, for example, different TCP phases or Mixtures of TCP phases etc. are often considered to be absorbable Bone replacement materials used.

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 moldings or granules are first treated with a base carrying OH ^- ions 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, which has a higher calcium release than the underlying body (see DD 2 58 713).

A particle mixture is associated with the term granulate the grain ranges between 63 and 800 micrometers, preferably between 200 to 500 micrometers for the Use in the dental field and 200 to 800 Micrometers for use in the orthopedic field.

In principle, all bases which are free of toxic accompanying components, such as, inter alia, NaOH, KOH, Ca (OH) ₂, are suitable for the treatment with the base bearing OH ^- ions. This choice of base has a determining influence on the result of the release of prostaglandins of the E series or their derivatives or stabilized prostaglandins of the E series and is also taken into account from the point of view of whether the presence of - in itself small amounts - the Base-forming cations are detrimental to the intended use or not. The treatment with an OH ^- ion-carrying base is carried out in principle in corresponding aqueous solutions of pH values between about 7.5 and 9.5. With regard to the stability of prostaglandins of the E series or their derivatives 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 (0.5 to 3 hours).

It has now surprisingly been shown that in this way pretreated TCP material similar to others surface-reactive (bioactive) carriers as well E-series prostaglandin or its derivatives or stabilized prostaglandins of the E series adsorptive or can bind chemically. Furthermore, it was found that by Silanization and subsequent coupling of E-series prostaglandins or their derivatives or stabilized prostaglandins of the E series, the release can be delayed even further. It is of course, that in this way the total PG implanted can be higher than with untreated granules. A longer-lasting release of PG is thus Implantations possible.

The silanization can be achieved by a large number of silanes  general formula:

take place in which R¹, R² and R³ may be the same or different and may 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, wherein R⁵ is an alkyl radical with 1 to Can be 5 carbon atoms or hydrogen.

The experiments showed that often a silane-specific PG can bind to bone substitute material. Preferably the silanes were gamma-aminopropyltriethoxysilane and glycidoxypropyltriethoxysilane used.

The silanization is usually carried out with 1 to 10% Silane solutions in an ethanol / water / HCl mixture in the Mixing ratio between 40 to 60 to 60 to 40, preferably with a 50% alcoholic HCl solution a pH of 2.0 to approx. 4.5. The duration of treatment varies between about 30 minutes depending on the silane and 24 hours. Then the silanized Bone replacement material in a phosphate buffer or PBS solution under almost physiological conditions rinsed several times with regard to the pH. Possibly can also be washed with an alcoholic solution and then the carrier material at 150-250 ° C. Be subjected to drying process.

When using the gamma-aminopropyltriethoxysilane can additionally activation before treatment with the Active ingredient can be made. It is suitable for this purpose u. a. a 1 to 10% glutardialdehyde solution, where as Solvent PBS solution is used or a 0.01 to 0.1 molar Sodium potassium phosphate buffer solution. This activation is  possible through a multi-hour, mostly 24-hour Treatment between 5 and 40 ° C. Then there is another To wash. As prostaglandins come in the sense of the present Invention description the PG of the E series, whose Stabilized forms or derivatives of the PG of the E series for Use that is coupled to this silanized layer will.

In the preparation of the mixtures for the coupling between PG and the inorganic material that first the PG of the E series or its derivatives or stabilized forms of the PG of the E series, preferably PG E₁ and PG E₂, 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 will. So-called stabilized PGs are also particularly suitable, because with chemical stabilization mostly one Improvement in water solubility goes hand in hand.

The bone substitute materials are presented 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 5 milligrams of PG per milliliter Solvent for about 15 to 300 minutes at room temperature incubated. The pH of these solutions can be limited vary from about 4 to 8; it makes sense to work but under approximately physiological conditions or in acidic area. The subsequent drying is carried out approx. 37 ° C in a vacuum.

This chemically surface-active (bioactive) Bone replacement materials coupled PG of the E series or their derivatives or stabilized products from PG of the E series results in implantation as bone replacement material much better success than using just one of these substances, the use of PG at the implantation site is hardly possible even without this method. On the other hand results in the use of surface-active (bioactive)  Implant materials by themselves are not one either such a good effect of osteoinduction. Especially clear will this surprising effect when using resorbable bone substitute material as well as being strong improved new bone formation - presumably through the accompanying improvement in the supply situation of the peri-implant tissue - also faster absorption observed as a pleasant and desirable side effect could be.

Especially for human use, it is necessary it is essential to adhere to the limit concentrations on PG, for example about 0.5 to 6 milligrams per implantation. For the purpose of the mentioned dilution, especially at the treatment of large-lumen bone defects, but also to further delay the release it is possible to treated substances with an organic, biocompatible, to coat resorbable (biodegradable) polymer. Out In principle, all of the group of these polymers are suitable where polyhydroxybutyric acid, gelatin, resorbable Polyurethanes and polylactates seem particularly suitable. This inevitably results in a further delay in the Release of the E series prostaglandins or their Derivatives or stabilized prostaglandins of the E series.

If there is no further delay in the release, so these fabrics can also be combined as a shape simple particulate mixtures are used, almost a dilution with the E series prostaglandins or their derivatives or stabilized prostaglandins of the E series to achieve treated granules. Under this Aspects of simple dilution are of course also other absorbable organic materials suitable, the above. Purpose in wrapping can not meet how for example collagen. Studies have shown that the combined use of PG granules provided with PG, with PG-free, surface-modified TCP and Collagen for the best results at the  Defective filling led.

The invention is illustrated below by examples are explained.

Embodiments

The process step of treating the calcium phosphate-containing carrier 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 containing OH ^- ions

A) The carrier material is in an aqueous NaOH solution heated at pH 8.0 at 90 ° C for 2 hours. Subsequently the material at 120 ° C for 120 minutes dried.

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

(b) silanization

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

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

(c) PG impregnation Example 1

There were 2 grams of alpha-TCP granules the grain size between 200 to 500 micrometers, that pretreated according to Example B) with a base was silanized according to Example I with a ethanolic PGE₁ solution, the total of 10 milligrams of PG E₁ contained, incubated for about 60 minutes and then dried at 37 ° C in a vacuum.

4-month-old Wistar rats were used as the experimental model Defects in the tibial metaphysis are set, each with 0.2 Grams of the treated material were replenished. As Control group, animals were selected that were untreated Got material implanted. To determine the osteogenesis and after 3 months the animals became osteoinduction killed and various histological examinations carried out.

It was found that the new bone formation and surprising absorption is also the most extensive in that group had advanced, the material treated with PGE₁ had been implanted.

Example 2

There were 2 g shaped implant body consisting of a glass ceramic based on apatite and wollastonite silanized according to Example II and then with 2.5 ml an ethanolic solution for 60 minutes, the 1 milligram PG E₁ (4 milligrams PG E₁ per milliliter). The treated material was dried analogously to Example 1 and implanted. Untreated was also used here  Comparison of implant material.

It was also shown here that the formation of bones in the In the case of samples treated with PG, significantly further had advanced.

Example 3

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

As expected, an analogue was also used here Test result for example 1 reached. It was confirmed the impression that the absorption by the combined application was increased significantly, even higher than compared to samples in which PG is virtually physical had been added mixed.

Example 4

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

Animal experiments were carried out in accordance with Example 1, where each 0.3 grams of the treated granules per Laboratory animal were used.

Here, too, there was an improvement over the Control group implanted with PG-free material.

Example 5

PG-treated alpha-TCP granules which was prepared according to Example 1, with the mixed the same amount of collagen.

Mini pigs of the mini lion type were used as test animals used. Bone defects were set in size  which were sufficient to each 0.5 grams of the mixture to record.

Defects served as a control, those with PG-free TCP-collagen mixtures were replenished in an analogous manner. Also here it was shown that the combination with PG (PGE₁) to one significant improvement in osteoneogenesis.

Claims (27)

1. A process for the preparation of an osteoinductive bone substitute material based on calcium phosphate-containing substances, characterized in that a bioactive calcium phosphate-containing bone substitute material which has OH groups and / or silane groups on its surface, with a prostaglandin (PG) of the E series or their derivatives or a stabilized form of the E series PG or mixtures thereof. 2. The method according to claim 1, characterized in that one bioactive calcium phosphate-containing bone substitute, the has OH ions on its surface, with a PG of the E series or their derivatives or a stabilized form of E series PG or mixtures thereof. 3. The method according to claim 1, characterized in that one bioactive calcium phosphate-containing bone substitute, the has OH ions and silane groups on its surface, with an E-series PG or its derivatives or a stabilized one Form of PG of the E series or mixtures thereof treated. 4. The method according to any one of claims 1 to 3, characterized in that the OH ions on the surface of the bioactive Material from treating the material with a base, which is free of toxic accompanying components. 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, characterized in that one a bioactive calcium phosphate-containing bone substitute, which has silane groups on its surface, with a PG the E series or its derivatives or a stabilized form the PG of the E series or mixtures thereof. 7. The method according to any one of claims 1, 3 or 6, characterized in that the silane groups from a treatment of the material with a biocompatible silane coupling agent of the general formula 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, where R⁵ can be a lower alkyl radical having 1 to 5 carbon atoms. 8. The method according to claim 7, characterized in that the Silane from that from gamma-aminopropyltriethoxysilane, glycid oxypropyltriethoxysilane and / or mixtures thereof Group is selected. 9. The method according to claim 1 to 8, characterized in that the calcium phosphate-containing material selected from the group being made from alpha tricalcium phosphate; beta tricalcium phosphate; Hydroxylapatite; Glass ceramics and their mixtures and surface modified forms, and preferably Tricalcium phosphate is. 10. The method according to claim 1 to 8, characterized in that the calcium-containing material is an inorganic-organic composite is, wherein the organic material is a biocompatible Polyurethane, a monomer-free epoxidized polymeric hydrocarbon, a polyhydroxybutyric acid, a polylactate or is 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 that the calcium phosphate material is particulate and is absorbable.   13. The method according to claim 12, characterized in that the Particulate materials containing calcium phosphate granules with a grain size in the range of 63 to 1000 micrometers are, preferably in the range of 63 to 500 microns. 14. The method according to claim 1 to 11, characterized in that the calcium phosphate-containing material is not absorbable is. 15. The method according to one or more of claims 1 to 14, characterized in that the prostaglandin E from the Group selected from prostaglandin E₁ (PGE₁), Prostaglandin E₂ (PGE₂) and derivatives of PGE₁ or PGE₂ and stabilized forms of PGE₁ or PGE₂ exists. 16. The method according to claim 7 or 8, characterized in that the silanized material activates before PG treatment is, preferably by treatment with a glutardialdehyde solution over several hours. 17. The method according to claim 1 to 16, characterized in that to treat the product treated with prostaglandin E with biocompatible Wrapping materials surrounds. 18. The method according to claim 17, characterized in that the Wrapping material made from polyhydroxybutyric acid, gelatin, Polylactate is selected, where polyhydroxybutyric acid is preferred. 19. The method according to claim 1 to 16, characterized in that to treat the product treated with prostaglandin E with biocompatible organic resorbable substances mixed. 20. The method according to claim 19, characterized in that the organic resorbable from collagen, lactate, resorbable polyurethane existing group is selected with collagen being preferred.   21. The method according to one or more of claims 1 to 20, characterized in that the PG-treated material with untreated material is mixed. 22. Osteoinductive bone substitute material based on substances containing calcium phosphate, characterized by a mixture of

• a) one or more bioactive calcium phosphate-containing materials with prostaglandin E and / or its derivatives attached to the surface of these materials and
• b) free prostaglandin E and / or its derivatives or untreated bioactive calcium phosphate-containing materials, it being possible for the mixture constituents to be coated or organic resorbable biocompatible substances to be present as a further mixture constituent.

23. Implant according to claim 22, characterized in that it made of one or more materials containing calcium phosphate with deposited on the surface of these materials Prostaglandin E and / or its derivatives and a wrapper consists. 24. Implant according to claim 22, characterized in that it made of one or more materials containing calcium phosphate with deposited on the surface of these materials Prostaglandin E and / or its derivatives and organic resorbable substances. 25. Implant according to claim 22 or 23, characterized in that that the coating made of polyhydroxybutyric acid, gelatin, Polyactate existing group is selected, where Polyhydroxybutyric acid is preferred.   26. Implant according to claim 22 or 24, characterized in that that the organic resorbable material in a proportion from 1 to 40 parts by mass in%. 27. Implant according to claim 22, 24 or 26, characterized in that that the organic resorbable material from that of collagen, lactates, resorbable polyurethanes existing group is selected, with collagen preferred is.