JPS5915122B2 - Method for producing anticoagulant medical material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an anticoagulant medical material by heparinizing an acrylonitrile polymer.

Currently, many polymeric materials are used in the medical field, but a problem when using these polymeric materials is their biocompatibility.

A particular problem with materials that come into contact with blood is that these polymeric materials usually have the property of coagulating blood. Methods to improve the anti-coagulant properties of polymeric materials include making the material itself less likely to form a blood clot, and preventing the formation of blood clots by combining it with heparin, a natural anti-coagulant. A method has been tried to do so. As an example of the latter, a method of treating a cellulose membrane with bromine cyanide and then fixing heparin by covalent bonds is described in Transactions of the American Society for Artificial Internal Organs, Vol. 22, p. 654. (1976). On the other hand, 25 liters of acrylonitrile (
(hereinafter abbreviated as AN)-based polymers have been attracting attention, and compared to copper ammonia rayon, which has traditionally been used as a material for artificial kidneys, this AN-based polymer has lower ultrasonic overrate and lower medium molecular weight solutes. It is characterized by excellent permeability and strength, and its use is expected to expand in the future, not only in the field of artificial kidneys but also in other medical fields. Various methods for improving biocompatibility have also been attempted when using this AN-based polymer as a material. For example, JP-A-54-34
No. 416 discloses an attempt to impart anti-blood coagulability to the material by copolymerizing AN with a copolymerizable monomer having a sulfonic acid group 35 or a salt thereof. However, simply introducing sulfonic acid or sulfonate does not necessarily provide sufficient anticoagulant properties.

The present inventors aimed to develop an anticoagulant AN-based polymer that combines heparin, a good natural anticoagulant, and an AN-based polymer, and as a result of intensive research, they found that an AN-based polymer and glycidyl By reacting with a polymerizable monomer having an epoxy group such as acrylate or glycidyl methacrylate, a graft copolymer having an AN-based polymer as the main chain, which was previously considered difficult, can be easily synthesized. It became clear that the branch polymer of the obtained graft copolymer was highly reactive because it had epoxy groups, and that a material with excellent anticoagulant properties could be obtained by reacting this with heparin. This invention has been achieved. That is, the present invention is characterized in that an AN-based polymer is reacted with glycidyl acrylate or glycidyl methacrylate in the presence of a polymerization initiator, and the reaction product obtained by the reaction is reacted with heparin. The present invention provides a method for producing an anti-blood coagulant AN-based medical material.

The anticoagulant medical material obtained by the method of the present invention has a method of binding heparin to the grafted branch polymers, so that the amount of heparin bound can be varied over a wide range by changing the number of branch polymers and the degree of polymerization. It has the characteristic of being able to be controlled.

The AN-based polymer used in the present invention may have an AN content of 30% by weight or more, but in order to exhibit the characteristics of the AN-based polymer, it must contain 80% by weight or more of AN. is preferred.

As the copolymerization component contained in the AN polymer, acrylic acid, methyl acrylate, acrylamide, itaconic acid, vinyl chloride, styrene, vinylidene chloride, methyl methacrylate, sodium allylsulfonate, etc. can be used. The AN polymer can be produced by a commonly used industrial method, such as aqueous suspension polymerization or solution polymerization.

Glycidyl acrylate or glycidyl methacrylate used in the present invention is produced by AN in the presence of a polymerization initiator.
It is used to react with an AN-based polymer to obtain a graft copolymer having an AN-based polymer as the main chain, which has been considered difficult in the past.

Since the branch polymer of the graft copolymer thus produced has epoxy groups, the epoxy groups react with heparin, making it possible to fix heparin. However, among these two types of polymerizable monomers, due to their ease of handling,
Glycidyl methacrylate is industrially preferred. Examples of the polymerization initiator used in the present invention include a cerium salt initiator represented by ceric ammonium nitrate, a hydrogen peroxide-metal salt initiator represented by ferrous hydrogen peroxide salt, and a hydrogen peroxide-metal salt initiator represented by ferrous hydrogen peroxide salt. 2″-Azobis(2-amidinopropane)
Water-soluble azo compounds such as hydrochloride can be mentioned, but ceric ammonium nitrate and hydrogen peroxide Fe2+ systems are particularly preferred.

Potassium persulfate monoacidic sodium sulfite system, which is a typical redox initiator, can also be used in the present invention, but when this initiator system is used, residual epoxy groups in the generated branched polymer The amount tends to decrease. The graft copolymer of the present invention can be prepared by using AN in the presence of the polymerization initiator.
It is obtained by reacting glycidyl acrylate or glycidyl methacrylate with a polymer.

The graft copolymerization reaction can also be carried out in a solution state in which the AN polymer is dissolved in an organic solvent such as N-N-dimethylformamide or dimethyl sulfoxide, and then the reaction product is applied to the surface of the material. Heparin can be fixed by forming a membrane, precipitating and coagulating in a non-solvent such as water, and then reacting with heparin in a heparin solution. Alternatively, after dissolving the AN-based polymer in a solvent such as nitric acid, N-N-dimethylformamide, dimethyl sulfoxide, zinc chloride aqueous solution, or sodium thiocyanate aqueous solution, and forming it into a molded article such as a hollow fiber, membrane, or fiber, Heparin can be fixed by subjecting a molded product of the AN polymer to a solid-liquid reaction with glycidyl acrylate or glycidyl methacrylate in a solvent such as water, acetone or dioxane, and then reacting with heparin. As a medium for reacting the molded article with glycidyl acrylate or glycidyl methacrylate, an aqueous medium is preferable in consideration of reaction rate and medical use. Further, the reaction between the AN polymer and glycidyl acrylate or glycidyl methacrylate is preferably carried out under conditions such that ring-opening of the epoxy group is difficult, for example, at a low temperature. The reaction temperature is 0°C to 90°C, preferably 4°C to 50°C. Furthermore, in order to avoid ring opening of the epoxy groups of the graft copolymer after the reaction, it is preferable to react with heparin within a short time after the graft reaction. Next, a method for fixing heparin will be described.

In order to react the reaction product of the AN polymer and glycidyl acrylate or glycidyl methacrylate with heparin, it is preferable that the epoxy group is used efficiently in the reaction, and for this purpose, homopolymer and unreacted After washing the monomer, it is preferable to contact it with heparin within a short time. The reaction medium in this case may be any medium as long as it is inert to the reaction product and heparin and can dissolve heparin, but an aqueous medium is most preferred. The reaction temperature may be within a range in which heparin activity is not lost, but it is 0°C to 90°C, preferably 4°C.
~50°C. In order to increase the reaction efficiency, it is possible to add a catalyst such as pyridine or acetic acid, but considering that it is used for medical purposes, it is preferable to use no catalyst. Also,
The proportion of the graft component in the graft copolymer is 2
It is effective in the range of ~80%, but the preferred range is 2 to 2
It is 0%.

The reaction product of the AN-based polymer to which heparin has been immobilized in this manner can be confirmed by the fact that it exhibits metachromatic color when stained with Azure A. The present invention will be explained in more detail with reference to Examples below.

Blood coagulation properties (heparin activity properties) in the Examples were determined by either the following method using standard human plasma or the LindhOlmtest using dog whole blood.

1 Method using standard human plasma Behringwerke A.G.
), put 1 ml of standard human plasma into a 10 mm diameter test tube, keep it at 37°C for 5 minutes, and soak it in 25% saline overnight.
A 6.0cm sample piece washed with physiological saline is immersed and left for 30 minutes.

After 30 minutes, take out the sample piece and immediately add 0 calcium chloride.
．． Add 0.2 ml of 1 molar aqueous solution and measure the clotting time in the same manner as the conventional Lee-Wllte method.

2 Lindholm test using dog whole blood Heparinized film was added to 25% (W/V) saline solution 500
By extracting 1y twice with m1 for 10 hours each time, unbound heparin that is easily released is removed.

Next, place this film on a glass plate, press it with a 5 mm thick silicone gasket with a 2.0 (1-J model V1φ) hole in the center, and then place a glass plate with a hole of the same diameter. After draining the first 0.5 ml from the dog's jugular vein, collect about 5 ml of whole blood, drop 0.5 ml of this onto each sample film, and tighten it. Spread it evenly and make the first 20
Tilt the tube every 5 minutes, and every 2 minutes after 20 minutes, and measure the time until the blood coagulates and stops moving using a Lindholm cell. 1 each for 3 dogs
The measurements were repeated and the average value is shown. Example 1 AN homopolymer (number average molecular weight 5000
0) was synthesized.

After dissolving the polymer in 70% nitric acid kept at 0°C,
A film was coated on a glass plate, coagulated in distilled water, and the solvent was removed.
After removing the solvent, the film was vacuum dried overnight to reduce ANlOO%.
I got the film. A film (about 50 μm thick) was cut out to a size of 5 CTrL in diameter and used as a sample. 300 ml of distilled water was charged into a 500 ml four-bottle flask equipped with a reflux condenser, and the above film 1y was placed in the flask, and the flask was purged with nitrogen.

Next, 1.57 glycidyl methacrylate (hereinafter referred to as GMA) was added, followed by 17 T11 N/10 mononitric acid and 0.267 ceric ammonium nitrate, and the mixture was heated at 30°C.
The mixture was allowed to react for 2 hours. After the reaction, the film was immediately immersed in acetone to wash off the GMA and GMA homopolymer attached thereto. Next, extraction was carried out using acetone as an extractant for 3 hours using a Soxle extractor, and the adhered GM was further removed.
A and GMA homopolymer were washed off. Thereafter, the film was vacuum dried overnight at room temperature. The grafting rate of the obtained graft copolymer film was 58%. The grafting rate was calculated using the following formula. In addition, the film was
- Although it was immersed in dimethylformamide (hereinafter referred to as DMF), it did not dissolve.

When the infrared spectrum of the obtained film was measured, absorption peaks of about 1730 CTfL-1 (ester bond) and about 905 cfL-1 (epoxy group) belonging to GMA were clearly seen. The above film, which had been washed with acetone after the graft reaction, was placed in a 10% aqueous heparin solution and reacted at 50° C. for 24 hours. After the reaction, the film was washed with water and then immersed in 25% saline overnight. Thereafter, it was immersed in physiological saline overnight. Next, the heparin activity of the film was measured using standard human plasma. the result,
No plasma coagulation was observed even after 24 hours had passed. Plasma coagulated in 9 and 20 minutes for untreated AN-based polymer films and for films in which such films were simply immersed in a 10% heparin solution and reacted at 50°C for 24 hours, respectively. Example 2 Various AN-based polymers shown in Table 1 were synthesized by aqueous suspension polymerization, and films were prepared in the same manner as in Example 1.
GNA was grafted using the initiator system shown in Table 1.

Furthermore, it was reacted with heparin in the same manner as in Example 1. The results are shown in Table-1. The solvent used during film formation was DMF only in Experimental Washing 2, and 70% nitric acid in all others. In addition, the numerical values in the AN-based polymer composition are shown in the weight ratio of the charged materials. Heparin activity was also expressed by clotting time using human plasma. Example
A polymer consisting of 3AN/methyl acrylate/sodium methallylsulfonate (charged weight ratio) of 93/6/1 was synthesized by aqueous suspension polymerization using a polymerization catalyst based on potassium persulfate and sodium monosulfite.

This reaction product was reacted with GMA in the same manner as in Example 1, and then washed with acetone. The grafting rate was 10%. The film washed with acetone was then placed in a 5% aqueous heparin solution and reacted at 50°C for 24 hours.
After the reaction, the film was thoroughly washed with water to remove attached heparin. Furthermore, it was immersed in 25% saline overnight. This operation was repeated three times. Thereafter, it was immersed in physiological saline overnight. When we measured the infrared spectrum of this film, it was approximately 1730? which belongs to GMA? -1 and a remarkable absorption peak at about 905 cm-1 attributed to the epoxy group. The anti-blood coagulability of the film was evaluated by Lindholm test using blood immediately collected from a vehicle dog.

The results are shown in Table-2. For reference, as in Example 1, untreated and heparinized pools are shown for comparison. No blood coagulation was observed in the sample fixed with heparin by the method of the present invention even after 120 minutes. Example 4 The AN-based film 1y used in Example 3 and glycidyl acrylate 1y were reacted at 4° C. in the same manner as in Example 3 to fix heparin.

Claims (1)

[Claims] 1. Acrylonitrile polymer, or acrylonitrile and acrylic acid, methyl acrylate, acrylamide,
itaconic acid, vinyl chloride, styrene, vinylidene chloride,
An acrylonitrile polymer consisting of at least one copolymer component selected from methyl methacrylate and sodium allylsulfonate is reacted with glycidyl acrylate or glycidyl methacrylate in the presence of a polymerization initiator, and the resulting product is obtained by the reaction. A method for producing an anticoagulant medical material, which comprises reacting a reactant with heparin. 2. Claim 1, wherein the acrylonitrile-based polymer contains 80% by weight or more of acrylonitrile.
Manufacturing method described in section. 3. The manufacturing method according to claim 1, wherein the polymerization initiator is hydrogen peroxide-Fe^2^+ system. 4. The manufacturing method according to claim 1, wherein the polymerization initiator is ceric ammonium nitrate or 2,2-azobis(2-amidinopropane) hydrochloride.