JPS6157788B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an antithrombotic medical material. More specifically, the present invention relates to a method for producing an antithrombotic medical material, which comprises treating a molded article having a surface that comes into direct contact with blood with actinic radiation in the presence of a heparin derivative having an unsaturated group. BACKGROUND OF THE INVENTION Currently, medical materials having surfaces that come into direct contact with blood are made of materials such as soft vinyl chloride resin, silicone resin, and natural rubber. However, as is well known, blood clots and forms thrombi when it comes into contact with these materials. Therefore, even silicone resin, which is said to have relatively high compatibility with blood, forms a thrombus in a short time when it comes into contact with blood, so it is necessary to use it in combination with an antithrombotic agent. Conventionally, as such antithrombotic agents, heparin, coumarin, dipyrytamol, etc. have been used when directly administering to the human body, and when blood is stored outside the body in a blood bag etc., citrate or ACD solution which is a mixture thereof has been used. etc. are used. However, there are various drawbacks to using this antithrombotic agent.
For example, administering heparin to the human body increases the risk of bleeding, and blood mixed with ACD fluid cannot be used as is in the human body. Furthermore, this antithrombotic agent does not impart antithrombotic properties to the medical material itself. From these points, attempts have been made in recent years to impart antithrombotic properties to medical materials themselves. The main method for imparting antithrombotic properties to medical materials itself is to attach heparin to the surface of the material or impregnate the cortical layer of the material, and to release the heparin slowly upon contact with blood. Methods for imparting gender have been studied and proposed. However, with this method, if the amount of heparin deposited or impregnated is small, the lifespan of antithrombotic properties will be significantly shortened, which poses a practical problem. Conversely, if the amount of heparin is too large, the sustained release time will become longer, but the amount of sustained release will also increase. As with systemic administration mentioned above, it has the disadvantage of increased risk of bleeding. Furthermore, even if a desired amount is adhered or impregnated, the lifetime of retaining antithrombotic properties is relatively short, and further improvements are desired. As a result of intensive studies aimed at developing medical materials with further improved antithrombotic effects, the present inventors developed a molded article with a surface that comes into direct contact with blood in the presence of a heparin derivative having a specific unsaturated group. The present invention was achieved by discovering that an excellent antithrombotic effect can be imparted to the surface by treating the surface with actinic rays. That is, the present invention provides a molded article having a surface that comes into direct contact with blood according to the following formula: (However, in the formula, R ₁ , R ₂ and R ₃ each represent a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, and H
_ep indicates heparin residue. n is a number of 1 or more. ) is a method for producing an antithrombotic medical material, which is characterized in that it is treated with actinic radiation in the presence of a heparin derivative having an unsaturated group represented by: The molded article in the present invention is made of thermoplastic resin such as polyethylene, polypropylene, polyvinyl chloride,
polyester, polyamide, polycarbonate,
Molded products made of polyurethane, silicone resin, etc.; elastomers such as natural rubber, synthetic rubber, polyester ether elastomer, polyester ester elastomer, etc.; cellulose derivatives such as acetyl cellulose; and other resins. In addition, molded products can be formed, such as catheters, blood bags, etc.
It may be a blood circuit, an artificial kidney A-V shunt, a dialysis membrane for an artificial kidney, a tube popping chamber for a blood pump, etc., or it may be a precursor molded product such as a film, a hollow body, etc. before being processed into these. good. The heparin derivative having an unsaturated group used in the present invention is represented by the following general formula []. (However, in the formula, R ₁ , R ₂ and R ₃ each represent a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms.n
is a number greater than or equal to 1. _Heparin residues are shown. ) In the general formula [], R ₁ and R ₂ are preferably hydrogen atoms, and R ₃ is preferably a hydrogen atom or a methyl group. The above heparin derivative is a compound in which an unsaturated group is introduced into the alcoholic hydroxyl group of heparin via an ester bond, as represented by the above formula (). The unsaturated group may be introduced at any of the many alcoholic hydroxyl groups in heparin, and the number thereof may be one or more. The maximum number of ester bonds is determined by the number of alcoholic hydroxyl groups in heparin. This heparin derivative can be obtained by an esterification reaction between an acid halide or acid anhydride of an unsaturated carboxylic acid represented by the general formula [] and heparin. R ₁ , R ₂ and R ₃ in the unsaturated carboxylic acid represented by the above formula () are the same as R ₁ , R ₂ and R ₃ in the formula (), and most preferably R ₁ and R ₂ are It is acrylic acid or methacrylic acid, which is a hydrogen atom and R ₃ is a hydrogen atom or a methyl group. Further, as the halogen forming the acid halide of an unsaturated carboxylic acid, a chlorine atom or a bromine atom is preferable, and a chlorine atom is particularly preferable. Preferred specific examples of the acid halides and acid anhydrides of unsaturated carboxylic acids include acrylic acid chloride, methacrylic acid chloride, acrylic anhydride, and methacrylic anhydride. Such a compound itself has high activity and reacts very easily with the alcoholic hydroxyl group in heparin to produce a heparin derivative represented by the formula (). The position of the ester bond in the heparin derivative may correspond to any one or more of the many alcoholic hydroxyl groups in heparin, and the position and number thereof are not particularly limited. Hereinafter, specific production examples of heparin derivatives will be explained. In the reaction between an acid halide or acid anhydride of an unsaturated carboxylic acid and heparin, if the acid halide or acid anhydride is liquid, the reaction can occur in a homogeneous dissolved system or a heterogeneous undissolved system after heparin is added. However, it is preferable to react in a homogeneous dissolution system using a solvent. The solvent that can be used is one that is substantially non-reactive with the acid halide or acid anhydride of the unsaturated carboxylic acid represented by the above formula (), such as formamide, acetonitrile, chloroform, toluene, etc. can. However, these solvents usually have a weak ability to dissolve heparin. Therefore, in this case, it is preferable to use heparin after solubilizing it. Examples of the solubilization treatment include converting heparin into a quaternary ammonium salt. Examples of such ammonium chlorinating agents include cetylhyridium chloride and cetyltrimethylammonium bromide, with cetylpyridium chloride being particularly preferred. The reaction between the acid halide or anhydride of an unsaturated carboxylic acid and heparin (or quaternary ammonium salt of heparin) is preferably carried out at 100°C or lower, preferably from 0°C to 70°C, and more preferably at room temperature. Too high a temperature is undesirable because it causes deactivation of heparin. Further, the reaction time depends on the reaction temperature, but is usually about 5 seconds to 50 hours. Furthermore, conventionally known catalysts can be used in the esterification reaction with acid halides and/or acid anhydrides. Examples of such catalysts include basic catalysts such as triethylamine and pyridine, but other esterification catalysts can also be used. The obtained reaction product is separated by reprecipitation, etc., and then thoroughly washed by repeating reprecipitation and washing. As the solvent used for reprecipitation, in addition to acetone, chloroform, etc., it is preferable to use a compound capable of removing an acid halide or acid anhydride of an unsaturated carboxylic acid by hydrolysis, such as water, ethanol, etc. In this way, the heparin derivative represented by formula () can be easily obtained. As the heparin used for the esterification,
Heparin, which is commonly used as an antithrombotic agent, can be used. This heparin is usually extracted from animal living bodies as a mucopolysaccharide, such as Hog Intestine,
Whale intent
It is obtained from living organisms such as Intestine and is usually commercially available as a sodium salt. The activity indicates a value measured by a conventionally known method, and can be used for medical purposes as recognized by, for example, the Japanese Pharmacopoeia, the United States Pharmacopoeia, etc. In the present invention, a molded article having a surface that comes into direct contact with blood is treated with actinic radiation in the presence of the above-mentioned heparin derivative having an unsaturated group. Here, "in the presence" means a state where the surface of the molded product is in contact with the heparin derivative or a state where the surface layer of the molded product is impregnated with the heparin derivative. Specifically, for example, the following method is used. Preferably shown. About 0.001 to 100% by weight of a heparin derivative having an unsaturated group is dissolved in a solvent capable of uniformly dissolving the heparin derivative having an unsaturated group, such as water, formamide, physiological saline, water/ethanol mixed solvent, etc. There is a method of treating the molded article with actinic rays while uniformly contacting the surface of the molded article with a homogeneous solution that comes into contact with blood. A preferred method for bringing about this uniform contact is a so-called immersion method in which the molded article is immersed in a solution. In the actinic ray treatment, an organic solvent that can be mixed uniformly with the above solvent, such as dimethylformamide, dimethyl sulfoxide, acetonitrile, various alcohols, dioxane, etc., is used in combination, and the actinic ray irradiation is carried out in a state where the affinity with the molded product is increased. Good too. The concentration of the heparin derivative having an unsaturated group in the heparin mixed solution is preferably 0.01 to
50% by weight, more preferably 0.05-10% by weight. Furthermore, in the actinic radiation treatment, an unsaturated monomer may be added to the heparin mixed solution in an amount of 1 to 10,000% by weight based on the amount of heparin derivative. Further, a preferred amount of unsaturated monomer is 10 to 5000% by weight based on the amount of heparin derivative, and a particularly preferred amount is 50% by weight.
~1000% by weight. When the unsaturated monomers are used together, it is preferable to add and mix them to a solution in which a heparin derivative is dissolved. Such unsaturated monomers are usually preferably vinyl compounds and allyl compounds, and specifically, for example,
Acrylic acid, methacrylic acid, methyl methacrylate, methacrylic acid and its derivatives such as acrylonitrile, hydroxyethyl methacrylate; styrene, vinyl chloride, vinylpyridine, N
Preferred examples include vinyl compounds such as -vinylpyrrolidone and the like. The above-mentioned unsaturated monomers can be used alone or in combination of two or more. Among these, it is preferable to use at least one hydrophilic unsaturated monomer, and examples of preferable hydrophilic unsaturated monomers include acrylic acid, methacrylic acid, hydroxyethyl methacrylate, and N-vinylpyrrolidone. The weight ratio of hydrophilic unsaturated monomer to hydrophobic unsaturated monomer is
It is recommended to use 0.1 to 10 times the amount. In the present invention, a molded article having a surface that comes into contact with blood is irradiated with actinic rays in the presence of a heparin derivative having an unsaturated group, and the following method is exemplified as the method of irradiating actinic rays. (a) A method of irradiating ultraviolet light at a temperature of -10°C to 70°C, preferably around room temperature, preferably in the presence of a photoinitiator; (b) A method of irradiating electron beams and gamma rays under the following conditions, for example: The irradiation dose is 0.001 Mnad or more and 100 Mnad or less, preferably 0.01 Mnad or more and 20 Mnad or less, and more preferably 0.02 Mnad or more and 10 Mnad or less. Although the dose rate is not particularly relevant, it is desirable that the target molded object can be irradiated uniformly. The temperature during irradiation can range from -10°C to 70°C, and room temperature conditions are generally advantageous. Among the above methods (a) and (b), method (b) is particularly preferred. The antithrombotic medical material of the present invention is achieved by bonding heparin to the surface of the molded article that comes into direct contact with blood, as described above. The antithrombotic medical material thus obtained has an extremely higher antithrombotic ability than silicone rubber materials conventionally used for medical purposes, and is free from the risk of bleeding due to large amounts of heparin. It is an improved and extremely excellent antithrombotic medical material. The present invention will be explained in more detail below using Examples. In addition, all parts in the examples mean parts by weight. Example 1 and Comparative Example 1 10 parts of cetylpyridinated heparin was dissolved in a mixed solution of 70 parts of dimethyl sulfoxide and 30 parts of chloroform, further 10 parts of acrylic anhydride was added, and the mixture was heated at 40°C for 30 parts.
Allowed time to react. The obtained reaction product was reprecipitated once with chloroform-ethyl ether and then with water.
After reprecipitating twice with ethanol and further treatment with a 2.1N aqueous sodium chloride solution, the sodium chloride was removed using a cellophane membrane according to a conventional method, and the product was further reprecipitated with water-ethanol for washing. The obtained white solid turned brown at 240-250°C, and elemental analysis showed that the amount of acrylic acid introduced was 13% of the hydroxyl groups of heparin. Cetylpyridium heparin is obtained by reacting heparin manufactured by Eastman Kodak (a product that passes the American Pharmacopoeia Standards) with cetylpyridium chloride in a conventional manner. A polyester ester block copolymer (reduced specific viscosity
1.53d1/g, 1.2g/ in orthochlorophenol
d1 (value measured at 35°C) was dissolved in 100 parts of chloroform, coated on a glass test tube with an inner diameter of about 1 cm and a length of about 10 cm, and dried. Next, the acrylic acid esterified heparin 1 obtained by the previous synthesis
After filling a test tube with a solution of 100 parts of water and ethanol (50-50 parts by weight) and irradiating it with 0.1Mnad gamma rays, it was mixed with water-ethanol (50-50 parts by weight), saline, and water. After washing thoroughly with water, it was air-dried at room temperature. When a heparin color development test was performed with an aqueous toluidine blue solution in this test tube, a reddish-purple color was observed, confirming the presence of heparin. In addition, blood collected from a rabbit was placed in a test tube that had not been subjected to a color test, and the hemolytic and thrombogenic properties were observed at 37°C. Rabbit blood was collected at a volume ratio of 9 parts to 1 part of a 3.8% sodium citrate aqueous solution, and after holding at 37℃ for 1 minute, it was mixed to 1/40.
An equal volume of M calcium chloride aqueous solution was gently mixed and used as blood. The results are shown in Table 1.

[Table] Comparative Example 1 is the result when a glass test tube was coated with a siliconized surface treatment agent manufactured by Fuji Systems. Examples 2 to 4 and Comparative Examples 2 to 4 15 parts of heparin and 0.5 parts of methacrylic acid chloride were added to 25 parts of formamide, and further 0.5 parts of pyridine were added, and the mixture was reacted at room temperature for 0.5 hours. Next, the reaction product was reprecipitated with ice-cold ethanol, dissolved again in water, and then mixed with ethanol/chloroform (volume ratio 60/4).
The white solid was purified and separated by reprecipitation with a mixed solution of 0). This white solid turns brown at 240-250℃,
Elemental analysis revealed that 21% of heparin hydroxyl groups were esterified with methacrylic acid. On the other hand, it is made of polytetramethylene terephthalate copolymerized with 60% by weight of polytetramethylene glycol having a molecular weight of 2000, and has a reduced specific viscosity of 2.31 d1/g.
(35 at a concentration of 1.2 g/d1 in orthochlorophenol)
5 parts of a polyester polyether block copolymer (value measured at °C) was dissolved in 100 parts of chloroform, coated on a glass test tube with an inner diameter of about 1 cm and a length of about 10 cm, and dried. Next, 0.67 parts of the previously synthesized methacrylated heparin was added to physiological saline/ethanol.
The test tube coated with the above copolymer was filled with a solution prepared by adding acrylic acid in the amount shown in Table 2 to a solution of 100 parts (volume ratio 70/30). into the test tube
After irradiating with 0.1 Mnad of gamma rays, the plate was thoroughly washed with physiological saline, water, and air-dried at room temperature. When a heparin color development test was performed with an aqueous toluidine blue solution in this test tube, a reddish-purple color was observed, confirming the presence of heparin. Next, a blood test was conducted in the same manner as in Example 1. The results are shown in Table 2.

[Table] Comparative Example 2 shows the results when a glass tube was coated with a siliconized surface treatment agent manufactured by Fuji Systems. In addition, in Comparative Example 3, 0.01 mg/ml was added to rabbit blood.
In Comparative Example 4, the same proportion of methacrylated heparin was added. Examples 5 to 7 and Comparative Examples 5 to 7 1.5 parts of heparin, 0.1 part of meacrylic acid chloride, and 0.1 part of pyridine were added to 25 parts of formamide, and after reacting at room temperature for 0.5 hours, the same as the methacrylated heparin in Example 2 was added. Purification of
A methacrylated heparin was obtained in which 7% methacrylic acid was introduced into the hydroxyl groups of heparin. Meanwhile, add 10 parts of acetylcellulose to 100 parts of acetone.
It was coated on a glass test tube with an inner diameter of 1 cm and a length of about 10 cm, and dried. Next, the inside of the acetyl cellulose coated test tube was filled with a solution prepared by dissolving 0.67 parts of the above-mentioned synthetic methacrylated heparin in 100 parts of physiological saline and adding acrylic acid in the amount shown in Table 3. After irradiating the test tube with 0.1 Mnad of gamma rays, it was washed with physiological saline, water, and air-dried at room temperature. The presence of heparin in this test tube was confirmed by color development with an aqueous toluidine blue solution. A blood test was conducted in the same manner as in Example 1 using this test tube. The results are shown in Table 3.

【table】

[Table] In the above table, Comparative Example 5 is the result when a glass tube was coated with a siliconized surface treatment agent manufactured by Fuji Systems. In addition, comparative example 6 uses rabbit blood.
Heparin was added at a rate of 0.01 mg/ml, and Comparative Example 7 added the above methacrylated heparin.
These are the results when 0.01 mg/ml was added.

Claims (1)

[Claims] 1. A molded article having a surface that comes into direct contact with blood is (However, in the formula, R ₁ , R ₂ and R ₃ each represent a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, and H
_ep indicates heparin residue. n is a number of 1 or more. ) A method for producing an antithrombotic medical material, characterized in that it is treated with actinic radiation in the presence of a heparin derivative having an unsaturated group represented by: