SK329592A3 - Method of preparation of bioactive material - Google Patents

Description

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Technical field

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The invention relates to a process for the preparation of bioactive medicaments suitable for medical applications, particularly for implantation in reconstructive surgery, based on technically readily available inorganic compounds and biopolymers.

BACKGROUND OF THE INVENTION

Several types of inorganic and organic materials suitable as bioactive materials for use in reconstructive medicine are known [H.V.Cameron et al., J. Biomed. Mater. Res., 11, 1979-86 (1977), D. F. William Williams Ed. Biocompatibility of Clinical Implant Materials, CRC Press, FL 1981]. Inorganic materials are mainly calcium-phosphorous compounds, the most mineralogical ones being hydroxylapatite and whitelockite [BVRejda et al., J.Bioeng., 1,93-97 (1976), CPATKlein et al., Biomaterials, 6,18992 ( 1985)], optionally tetrakalciumphosphate and octacalciumphosphate. [J.F. Osborn, Zahnärztliche Mitteilungen, 77, 2-12 (1987)].

In addition to these synthetically prepared materials, crushed coral, respectively, is used as a bioactive inorganic material, preferably of open porosity. coral hydrothermally modified to hydroxylapatite [Biomedical Materials, MRS Bull. 16, No.9, Sept. 1991]. In an attempt to mimic the porous bone structure, bioactive implants have recently been prepared as composite materials in which an inorganic component is combined with biopolymer functional components [J.P.MintIntyre et al., Ceramic Bulletin, 70, 1499 (1991)]. There are several patents using collagen and other proteins, some polysaccharides and the like.

Examples include replacement materials containing 100 to 2000 µm collagen and hydroxylapatite particles coated with morphogenic proteins extracted from fresh bovine bones [JP 02 182 260, CA 114, 12256], or a material that can be incorporated into broken bones formed on bases of calcium phosphorous compounds and collagen or collagen derived hardeners [PTC Int.Appl. WO 90 00 892, CA 114, 30178d]. Other examples are composite fillers in which the calcium phosphate powder is mixed with curing regulators (tannin, collagen and derivatives thereof) and organic acids [PTC Int. Appl. WO 90 01 341, CA 113, 84905m], or a similarly formed rigid foam to which bone morphogenic proteins and collagen can be added [JP 01 62 164, CA 112, 62692s].

However, their disadvantage is slower ossification and incomplete bone compatibility and thus a considerable risk in terms of joint strength and durability. However, the method according to the invention solves this problem.

SUMMARY OF THE INVENTION

According to the invention, a process for the preparation of bioactive material suitable for medical applications, in particular for implantation in reconstructive surgery, based on calcium phosphates and / or calcium phosphates, collagen and adjuvants, typically associated with sterilization, is carried out such that at least one of calcium phosphates with a particle size of 0,01 to 2 mm is homogenised with type I atelocollagen in a weight ratio of 1,5: 1 to 50: 1 and formed from a filter cake and / or pulp by the action of a physiological liquid consisting of at least one of the liquids selected from saline, blood plasma, blood, aqueous hyaluronic acid solution or sodium salt thereof, physiological hyaluronic acid solution and, as a rule, are immediately implanted.

An advantage of the method according to the invention is a markedly increased ossification, respectively. it induces increased osteogenesis, and thus high bond strength and durability, as a result of the quality of the individual synthetic components and Type I atelocollagen prepared from bovine achilles tendons, in particular by depleting telopeptides by enzymatic refining of the starting material used. Last but not least, it is the technical reproducibility and availability of both the components and the formation and structure of the resulting bioactive material.

Suitable calcium phosphates for carrying out the process according to the invention are, on the one hand, pure, in particular synthetically prepared calcium phosphates, such as calcium phosphate or a mixture of calcium phosphate with magnesium phosphate. Synthetic phosphate may be combined with natural phosphate if it does not contain radioactive impurities.

Suitable impurities may be aluminum, silicon, magnesium, iron, optionally zirconium, titanium compounds, especially in the form of oxides. It is important that they are not water soluble and toxic.

Particularly important as the calcium phosphates are hydroxylapatite, tricalcium phosphate, tetrakalcium phosphate, octacalcium phosphate and the like.

In terms of impurities and their suitability, the requirements are similar to those of the calcium phosphates mentioned. The particle size of the phosphates should be in the range of 0.01 to 2 mm. A finer grain than 0.01 mm is useful, but requires higher amounts of atelocollagen and ossification proceeds more slowly. Grain over 2 mm, in turn, is not particularly suitable in terms of formability and bond strength.

Filter cake means not only the phosphate meat with atelocollagen and possibly other excipients, retained on the filter, in the filter press, etc., but also centrifuged or, in extreme cases, sedimented meat.

Type I atelocollagen is generally prepared from fresh achilles tendons by enzymatic treatment using an enzyme such as e.g. trypsin, chymotrypsin and the like, taking particular care, as well as in the preparation and formulation of the other components, of an exact knowledge of their composition and sterility. An important operation for the preparation of this component is thorough fiberisation and fibrillation.

Suitable physiological fluids for carrying out the method of the present invention are redistilled water, saline, native or synthetic blood plasma, patient blood, resp. blood of a suitable donor, aqueous or physiological hyaluronic acid solution or aqueous sodium hyaluronate solution. A suitable ingredient of the bioactive material is bone morphogenic proteins extracted from fresh bovine bones.

Preferably, the bioactive meat is implanted immediately after its preparation, but can be applied later, while maintaining sterilizing and storage conditions.

Further data on carrying out the preparation process of the invention as well as other advantages are apparent from the exemplary embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Example 1.

The dispersed hydroxylapatite of the general formula Ca-Q (PO4) 6 (OH) 2 in an amount of 50 g with a dispersed particle size of 0.04 to 1.8 mm is mixed with 5 g of defibrillated resp. of fibrillated atelocollagen type I, obtained from fresh bovine achilles tendons. After the bioactive material has been completely homogenized, it is filtered. The filtrate is further formed into the desired form according to a bone defect into which it is implanted and will be a filler. The material is sterilized by γ radiation prior to implantation. Thus, when applied in vivo to a damaged dog tibia, it is filled, fixed and wound closed by inserting 1.38 g of bioactive material. After two months, the process of ossification of the bioactive material in the tibia of the dog is clearly observed by X-ray. After a yearly inspection, the perfect compatibility of the bioactive material and the treated bone is observed.

Example 2

The procedure is analogous to Example 1, except that 10 cm @ 3 of physiological saline containing 1% by weight are added to the homogenized suspension of bioactive material. sodium hyaluronate and 0.08 wt%. antibiotics. As early as 6 weeks, ossification of the bioactive material in the tibia of the dog was observed by X-ray and a perfect incorporation of the bioactive material into the treated bone was achieved after 10 months of control.

Example 3

The procedure is similar to that of Example 1, except that the weight ratio of hydroxylapatite is not 10: 1, but 4: 1, i. 10 g of atelocollagen are added to 40 g of hydroxylapatite. The ossification proceeds more slowly, and clear bone compatibility is observed after 3 months. The structure of the ossified material is reduced and the pores are larger than in Example 1.

Example 4

The procedure is analogous to Example 2, but the weight ratio of hydroxylapatite to atelocollagen is 40: 1. The ossification is already visible after 4 weeks. The structure of the ossified material is substantially less porous, with smaller pores.

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Example 5

The procedure is similar to Example 2, but the weight ratio of hydroxylapatite to atelocollagen is 2: 1 and the hydroxylapatite grain is 0.06 to 0.1 mm. The ossification is slow, observed only after 3 months and the ossified material has a high porosity with predominant macropores.

Example 6

Dispersed hydroxylapatite in an amount of 50 g with a dispersed particle size of 0.05-0.8 mm is mixed with 5 g of fibrillated atelocollagen type I and 0.5 g of bone morphogenic proteins. After homogenization, the material is filtered and allowed to dry under reduced pressure (2.67 kPa) at 26-30 ° C. The dried material is carefully crushed, sterilized by γ radiation. The material thus prepared is formed on the bone of an animal specified in Example 1 using blood plasma with an admixture of 10% by weight. blood mass of the patient, wherein the weight ratio of pulp to liquid is 12 to 8: 4, wherein the ossified portion is structurally homogeneous. The transition from bone to bioactive material is difficult to observe.

Example 7

The procedure is analogous to Example 6, except that 50 g of hydroxylapatite with an admixture of 0.3 wt. silica, 0.4 wt.%. alumina, 0.2 wt.%. ferric oxide and 0.1 wt%. A mixture of 30 g of fluoroapatite Ca 10 (PO 4) eF 2 with an admixture of 0.01% by weight is used. titanium dioxide, 0.6 wt. of magnesium oxide, 0.25 wt%. silica and 0.1 wt.%. ferric oxide having a grain size of 0.05 to 0.15 mm and 20 g of tricalcium phosphate Ca3 (PO4) 2, and the ossification of this bioactive material is also noticeable after 4 weeks.

Example 8

The procedure is analogous to Example 7 except that untreated collagen is used instead of Type I atelocollagen. After application, ossification occurs only after 7 weeks and more antibiotics are required.

Industrial applicability of the process

The method is suitable for use in clinical medicine, as well as in the pharmaceutical and chemical industries, in which starting materials and intermediates are produced and obtained in turn.

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Claims (5)

Patent claims A process for the preparation of bioactive material suitable for medical applications, in particular for implantation in reconstructive surgery, based on calcium phosphates and / or calcium phosphates, collagen and adjuvants, generally associated with sterilization, characterized in that at least one of calcium phosphates and / or calcium fluorate phosphates with a particle size of 0.01 to 2 mm are homogenized with type I atelocollagen in a weight ratio of 1.5: 1 to 50: 1 and formed from a filter cake and / or pulp by the action of a physiological liquid consisting of at least one of the liquids selected from saline, blood plasma, blood, aqueous hyaluronic acid solution, and is usually immediately implanted. Method according to claim 1, characterized in that the type I atelocollagen is prepared from telopeptide-free bovine achilles tendons, preferably by enzymatic purification. Preparation process according to claims 1 and 2, characterized in that to at least one of the calcium phosphates and / or calcium phosphates homogenized with type I atelocollagen in a weight ratio of 1.5: 1 to 50: 1, preferably 7 to 20: 1, 0.01 to 5.0% by weight is added. preferably 0.5 to 2% by weight. hyaluronic acid and / or its alkali salt, preferably lyophilized material, calculated on the dry matter of the formulated material. Method according to claims 1 to 3, characterized in that the calcium phosphates, such as tricalcium phosphate and / or calcium fluorate, preferably hydroxylapatite, are fortified with at least one of magnesium, silicon, iron, zirconium, titanium and aluminum compounds, preferably in in the form of oxides, in an amount of 0.1 to 20% by weight. Method according to Claims 1 to 4, characterized in that the further component of the bioactive material is bone morphogenic proteins, preferably prepared by extraction of fresh bovine bones in an amount of 1 to 20% by weight. calculated on the dry matter of the bioactive material.