JPH11322941A - Temperature response-type in vivo degradable polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer which is degraded in vivo in response to plural pieces of vital information (an enzyme and a temperature). SOLUTION: The objective polymer consists of a water soluble polymer having a three-dimensional network structure wherein a temperature-responsible polymer is introduced, as a graft chain, into an in vivo degradable polymer or a polymer having an in vivo degradable site in the molecule. As this polymer, of poly(N-isopropylacrylamide), polyacrylamide, polydimethylacrylamide, copolymers thereof, or a block copolymer of polyethylene glycol and polypropylene glycol are cited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The invention of this application relates to a temperature-responsive biodegradable polymer. More specifically, the invention of this application relates to a drug delivery system (DDS).
The present invention relates to a temperature-responsive biodegradable polymer that enables a new composition of a drug.

[0002]

2. Description of the Related Art Many biodegradable polymer materials intended for drug delivery systems up to now have a drug dissolved or dispersed in the material gradually decomposed by biodegradation of the material. It was limited to releasing hydrophobic polymer materials. This is because, in order to achieve drug release that is rate-limiting for degradation of a material, drug diffusion in the material is controlled to avoid drug leakage during non-degradation, and the instability (biodegradability) of the material is reduced. Although it was essential to limit the hydrolysis of the material to the vicinity of the surface by improving it, the biodegradation of the material is usually by enzymatic or non-enzymatic hydrolysis. From the standpoint of controlling the rate and the rate of hydrolysis, as a result, the material itself was made hydrophobic, limiting the rate of water intrusion, and increasing the instability of the polymer chains to increase the rate of degradation. . However, this has led to a decrease in storage stability as a preparation and a decrease in biocompatibility at the time of embedding of the material, resulting in restrictions on commercialization and application sites.

In recent years, taking into account the homeostasis of living organisms,
The use of stimuli-responsive polymers has made it possible to design intelligent formulations that release drugs only when needed by the living body, such as in diseases. Mainly, it has been studied to control the diffusion of a drug by a swelling-shrinking behavior of a polymer material in response to a stimulus. However, in this case, it was difficult to control the drug release ON-OFF by the biodegradation behavior of the material. Therefore, recently, stimulus-responsive degradability of a material has been studied by utilizing an active enzyme or a part of an enzyme reaction, and a system for delivering a drug in response to a disease is becoming possible.

[0004] However, in an actual disease, a variety of biological changes occur in association with each other. Therefore, it is not possible to determine the disease and determine the extent of the disease based on a single biological change to determine the amount of drug release. High risk. Even in actual medical treatment, such a composite is used in the biodegradation mechanism of a polymer material that controls drug release, as a comprehensive diagnosis is performed using multiple test items to identify a disease. There is a need for a comprehensive diagnostic function based on stimuli.

[0005] In other words, in order to realize a more advanced drug therapy, it is essential to realize an implantable drug carrier having a complex diagnostic function. There is a need for a polymer material that can be degraded in vivo.

[0006]

SUMMARY OF THE INVENTION The invention of this application is based on the stimulus response type having a complex diagnostic function in view of the problems of conventional biodegradable polymer materials as drug carriers as described above. From the viewpoint that polymer materials are required,
Provided is a hydrophilic polymer material (polymer hydrogel) that degrades in vivo in response to a plurality of biological changes (temperature and enzymes).

That is, the invention of this application firstly
A temperature-responsive polymer is introduced as a graft chain into a biodegradable polymer or a polymer having a biodegradable site in the molecule, which is a water-soluble polymer having a three-dimensional network structure. A temperature-responsive biodegradable polymer is provided. Secondly, the invention of this application relates to the above-mentioned polymer in a cell, tissue, organ or organ,
Degradation of biodegradable polymer chains or biodegradable sites occurs within a time range in which two different stimuli, namely, enzyme release and temperature rise, occur substantially simultaneously in a disease-specific manner, and the entire gel is degraded. Third, a temperature-responsive biodegradable polymer that undergoes degradation is divided into site-specific cells, tissues, organs, and organs in which two different stimuli, enzyme release and temperature rise, occur substantially simultaneously. The degradation of the biodegradable polymer chain or the biodegradable site occurs, and the degradation of the entire gel proceeds. The fourth is the biodegradable polymer. Alternatively, the whole or part of the polymer having a biodegradable site is a biodegradable oligopeptide or oligosaccharide chain, and is a temperature-responsive biodegradable biodegradable by a disease-specific enzyme. Polymer, 5th
Temperature-responsive biodegradable polymers whose temperature-responsive polymer is poly (N-isopropylacrylamide), polyacrylamide, polydimethylacrylamide, a copolymer thereof, or a block copolymer of polyethylene glycol and polypropylene glycol Provide a polymer.

Further, the invention of this application is, sixthly, that the graft chain of the temperature-responsive polymer and the biodegradable polymer network are compatible at a temperature lower than the body temperature, and in this state, the biodegradable polymer has high biodegradability. Gel decomposition does not proceed by an enzyme capable of decomposing a molecule, but the temperature-responsive biodegradable polymer in which enzymatic decomposition proceeds from the gel surface due to phase separation due to temperature rise due to disease. As the biodegradable polymer constituting the three-dimensional network, the constituent amino acids are alanine, valine,
Leucine, isoleucine, methionine, proline, phenylalanine, tryptophan, aspartic acid, glutamic acid, glycine, serine, threonine, tyrosine,
Cysteine, lysine, arginine, oligopeptide chain consisting of one or more of any of histidine, or dextran as a constituent polysaccharide, hyaluronic acid, chitin, chitosan, alginic acid, chondroitin sulfate, starch, oligosaccharide chain consisting of pullulan, each Eighth, a temperature-responsive biodegradable polymer having a molecular weight of 500 to 1,000,000, and eighthly, a temperature-responsive biodegradable polymer having a non-biodegradable water-soluble polymer as a part of its constitution. Ninth, a temperature-responsive biodegradable polymer that is a polyether or polyetherester is used as the non-degradable water-soluble polymer in the living body. Tenth, a non-degradable water-soluble polymer is used. The molecule has a molecular weight of 500-10000
In the biodegradable site contained in the molecular chain, the repeating unit is 1-5, and the constituent amino acids are alanine, valine, leucine, isoleucine, methionine, proline, phenylalanine, tryptophan,
Aspartic acid, glutamic acid, glycine, serine, threonine, tyrosine, cysteine, lysine, arginine, an oligopeptide chain consisting of one or more of any of histidines, or a repeating unit is 1-5, dextran as a constituent polysaccharide, hyaluronic acid, Provided is a temperature-responsive biodegradable polymer having an oligosaccharide chain composed of chitin, chitosan, alginic acid, chondroitin sulfate, starch, and pullulan.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The temperature-responsive biodegradable polymer of the invention of the present application has a single polymer chain crosslinked like a conventional biodegradable polymer hydrogel. Instead, it is characterized by forming a three-dimensional network structure in which a temperature-responsive polymer is introduced as a graft chain. This allows qualitative control of biodegradation, not just control of biodegradation rate. That is, the presence of an enzyme derived from a disease that degrades the polymer network alone prevents access of the enzyme due to steric damage based on the graft chain, and as a result, the decomposition does not proceed. On the other hand, when the temperature rises due to a disease due to the presence of the enzyme, for example, the graft chain contracts and phase-separates from the three-dimensional network, so that the enzyme can easily approach the network and hydrolysis proceeds sequentially from the gel surface. I do. As described above, when the decomposing enzyme and the temperature rise as stimuli are present alone, they are not decomposed, but are decomposed only when two are present at the same time. Therefore, the temperature-responsive biodegradable polymer of the present invention can recognize a more comprehensive biodegradation and can qualitatively degrade biodegradability as compared with a conventional polymer gel that degrades by a single stimulus. It has the advantage of being controllable.

As described above, in the present temperature-responsive biodegradable polymer, the qualitative change of the enzyme-decomposability is enabled by the structure in which the temperature-responsive polymer is introduced as a graft chain. This is expected to be applied to intelligent pharmaceutical products with multiple diagnostic functions and medical micromachines. In particular, the present invention allows for the design of formulations that achieve drug delivery based on a comprehensive diagnosis, such as the type and extent of disease, over a wide range of administration routes, such as intravenous, oral, and subcutaneous implants.

The structure of the temperature-responsive biodegradable polymer of the present invention will be described in more detail. First, the entire polymer constituting a three-dimensional network, or a part such as both ends of the polymer is an oligopeptide. It is suitable to be a biodegradable polymer such as a saccharide or an oligosaccharide and to be degraded by a disease-specific enzyme. Such 3
As the biodegradable polymer constituting the three-dimensional network, as described above, the constituent amino acids are alanine, valine, leucine,
Isoleucine, methionine, proline, phenylalanine, tryptophan, aspartic acid, glutamic acid,
Glycine, serine, threonine, tyrosine, cysteine, lysine, arginine, an oligopeptide chain consisting of one or more of histidine, or a constituent polysaccharide consisting of dextran, hyaluronic acid, chitin, chitosan, alginic acid, chondroitin sulfate, starch, and pullulan It is an oligosaccharide chain, and its molecular weight before formation of the three-dimensional network structure is preferably exemplified as having a molecular weight of 500 to 1,000,000, preferably 5000 to 100,000.

The polymer of the present invention may contain a non-degradable polymer such as polyether or polyetherester as a part thereof. For example, when a non-degradable water-soluble polymer such as polyethylene glycol is used, its molecular weight is 500-10000, desirably 1000-5000, and as a biodegradable site contained in its molecular chain such as both ends, A repeating unit is 1-5, and the constituent amino acids are alanine, valine, leucine, isoleucine, methionine, proline,
Phenylalanine, tryptophan, aspartic acid,
Glutamic acid, glycine, serine, threonine, tyrosine, cysteine, lysine, arginine, an oligopeptide chain consisting of any one or a plurality of histidines, or a repeating unit of 1-5, and dextran, hyaluronic acid, chitin, chitosan as a constituent polysaccharide , Alginic acid, chondroitin sulfate, starch, and pullulan.

The temperature-responsive polymers include poly (N-isopropylacrylamide), polyacrylamide, polydimethylacrylamide, copolymers thereof,
Alternatively, a block copolymer of polyethylene glycol and polypropylene glycol may be mentioned as a suitable one. These temperature-responsive polymers are introduced as a graft chain.
The molecular weight is 1000-100,000, preferably 20
Those in the range of 00-10000 are considered.

Above all, the temperature-responsive polymer graft chain and the biodegradable polymer network are compatible at a temperature lower than the body temperature, and in this state, gel decomposition proceeds by an enzyme capable of decomposing the biodegradable polymer. However, it is desirable that the graft chain and the degradable polymer are constituted so that the phases are separated by an increase in temperature due to a disease, and as a result, enzymatic degradation from the gel surface proceeds.

As described above, the temperature-responsive biodegradable polymer of the present invention can be produced in consideration of various conventionally known polymerization methods and conditions. The same applies to the introduction of the graft chain. For example, as a cross-linking method for forming a three-dimensional network structure, all generally known polysaccharide cross-linking methods are applied. Examples described later also show one of the methods, such as a method of introducing a double bond such as a methacryl group and crosslinking by a radical reaction, and an addition reaction with a diisocyanate compound which reacts with a hydroxyl group present in a polysaccharide. A crosslinking method or the like is appropriately employed.

The present invention will be described in more detail with reference to the following examples.

[0017]

EXAMPLES (Example 1) <A> N-isopropyl alcohol having an amino group at one terminal
Lilamide (IPAAm) -N, N-dimethylacryl
Synthesis of Amide (DMAAm) Copolymer (1) A predetermined amount of aminoethanethiol as a chain transfer agent, azobisisobutyroacrylonitrile (AIBN) as a radical initiator and IPAAm (8.2 g, 72 mmo)
l), DMAAm (1.8 g, 18 mmol) in DMF
Into a homogeneous solution. After radically polymerizing this solution at 75 ° C. for 15 hours in a nitrogen atmosphere, the solution was poured into diethyl ether to isolate a copolymer. The number average molecular weight was calculated by titration with a perchloric acid-acetic acid standard solution using crystal violet as an indicator (Table 1). The lower critical solution temperature (LCST) was determined by observing a change in the transmittance of visible light of 500 nm. FIG. 1 shows the result.

The molecular weight of 1 synthesized by changing the concentration ratio of the chain transfer agent and the monomer is 2600, 4200,
8,800. ^{From 1} H-NMR measurement, the IPAAm content of all copolymers was 0.7. The phosphate buffer solution (PB
As seen in the transmittance change during S), all IPA
Although the LCST of the Am copolymer is different from the molecular weight,
It was around 35 ° C.

[0019]

[Table 1]

<B> IP having a methacryl group at one end
Synthesis of AAm-DMAAm Copolymer (2) Copolymer (1) (5 g) of <A>, methacrylic acid chloride (2 ml) and an excess amount of triethylamine as an acid acceptor were dissolved in DMF. Stirred for hours. After completion of the reaction, the solution was poured into diethyl ether to isolate 2. <C> The IPAAm-DMAAm copolymer is used as a graft chain.
Synthesis of Dextran Hydrogel (3) Having Copolymer (B) (0.3 g), Dextran Methacrylate (Ma-Dex) (0.7 g), Ammonium Persulfate (APS) (50 mg) in 3 ml of DMSO To prepare a homogeneous solution. This solution was put into a gel producing spacer whose both surfaces were covered with glass, and then irradiated with light using a high-pressure mercury lamp at room temperature for 4 hours. After the reaction,
The hydrogel was cast in distilled water and allowed to equilibrate at room temperature for 10 days.

Dextran hydrogels having IPAAm copolymers having molecular weights of 2,600, 4200, and 8800 as graft chains are designated as 3a, 3b, and 3c, respectively, and
FIG. 2 shows the change in the degree of swelling of the hydrogel with the temperature change in BS. Swelling degree of all hydrogels is 10-45 ° C
Range was constant. Also, the lower the molecular weight of the graft chains in the hydrogel, the greater the degree of swelling of the hydrogel. FIG. 3 shows the temperature dependence of the permeability of the hydrogel in the swollen state. The permeability of all hydrogels decreased with increasing temperature and increased with decreasing temperature. (Example 2) IPAAm-DMAAm copolymer was used as a graft chain.
Analysis of Decomposition Behavior of Dextran Hydrogel to be Decomposed The hydrogel (20 × 20 × 2 mm) obtained in Example 1 cut into a plate (20 × 20 × 2 mm) was subjected to a dextranase-containing phosphate buffer solution (pH 7) at a predetermined temperature. .
4) and the change in weight was measured over time. The enzyme activity of dextranase at different temperatures was determined from the enzymatic degradation rate of dextran at each temperature, and the hydrogel degradation experiments were prepared so that the enzyme activities were the same at each temperature.

The above 3a was completely decomposed in any temperature range of 30 to 40 ° C., but no temperature dependency of the enzyme decomposability was observed (FIG. 4). 3b was completely decomposed at 35 ° C. or higher, but stopped decomposing at 30 ° C. after 4 hours and 30 minutes (FIG. 5). Decomposition of 3c did not proceed completely at any temperature, but its enzymatic degradation temperature dependence was observed (FIG. 6). The enzymatic degradability of the hydrogel was evaluated using the following decomposition index.

Decomposition index (%) = A / Ao × 100 (Ao: standard cumulative amount of decomposition, A: cumulative amount of decomposition obtained from experiments) FIG. 7 illustrates the characteristics of calculation of the decomposition index. ,
FIG. 8 shows the relationship between the calculated decomposition index and the temperature. The decomposition index of 3a was constant at all temperatures. The decomposition indices of 3b and 3c increased with increasing temperature.

[0024]

As described above in detail, the temperature-responsive biodegradable polymer of the invention of the present application degrades in a living body in response to a plurality of stimuli (enzymes and temperature). The contained drug is released only in response to a combined stimulus. In other words, after comprehensive diagnosis of the biological information such as the type and degree of the disease, the required drug release amount is prescribed, and the drug administration by the so-called complex diagnosis is possible by the function of the biodegradable hydrogel itself. Become. This is expected to enable highly effective pharmacotherapy for various diseases, such as treatment based on advanced diagnosis of diseases or treatment of complex diseases with various complications. In addition, since site-specific biodegradability in which complex stimuli exist can be realized, application as a medical micromachine that performs medical treatment at a specific site in a living body is also expected.

[Brief description of the drawings]

FIG. 1 shows an example of IPA having one terminal amino group.
It is a figure showing temperature dependence of the transmittance of Am-DMAAm copolymer.

FIG. 2 is a diagram showing the temperature dependence of the degree of swelling of a Dex hydrogel having an IPAAm-DMAAm copolymer as a graft chain.

FIG. 3 shows the temperature dependence of the permeability of Dex hydrogel in connection with FIG.

FIG. 4 is a diagram showing the enzymatic degradation behavior of Dex hydrogel (3a) as an example.

FIG. 5 is a diagram showing the enzymatic degradation behavior of Dex hydrogel (3b).

FIG. 6 is a diagram showing the enzymatic degradation behavior of Dex hydrogel (3c).

FIG. 7 is a diagram showing calculation of a decomposition index.

FIG. 8 is a diagram showing the relationship between the decomposition index of Dex hydrogels (3a, 3b, 3c) and temperature.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI A61K 47/34 A61K 47/34 C 47/36 47/36 C 47/42 47/42 C

Claims (10)

[Claims] 1. A temperature-responsive polymer is introduced as a graft chain into a water-soluble polymer having a three-dimensional network structure and a biodegradable polymer or a polymer having a biodegradable site in the molecule. A temperature-responsive biodegradable polymer characterized by being made. 2. A biodegradable polymer chain in a cell, tissue, organ, or organ within a time range in which two different stimuli of disease-specific enzyme release and elevated temperature occur substantially simultaneously. 2. The temperature-responsive biodegradable polymer according to claim 1, wherein the biodegradable site is decomposed, and the whole gel is decomposed. 3. A biodegradable polymer chain or biodegradable site in a site-specific cell, tissue, organ, or organ in which two different stimuli, enzyme release and temperature rise, occur substantially simultaneously. The temperature-responsive biodegradable polymer according to claim 1, wherein decomposition of the gel occurs and decomposition of the entire gel proceeds. 4. A disease-specific enzyme, wherein the whole or a part of the biodegradable polymer or the polymer having a biodegradable site is a biodegradable oligopeptide or oligosaccharide chain. The temperature-responsive biodegradable polymer according to any one of claims 1 to 3, which is decomposed by: 5. The temperature-responsive polymer is poly (N-isopropylacrylamide), polyacrylamide, polydimethylacrylamide, a copolymer thereof, or a block copolymer of polyethylene glycol and polypropylene glycol. The temperature-responsive biodegradable polymer of any of the above. 6. The graft chain of the temperature-responsive polymer and the biodegradable polymer network are compatible at or below body temperature, and in this state, gel degradation proceeds by an enzyme capable of decomposing the biodegradable polymer. The temperature-responsive biodegradable polymer according to any one of claims 1 to 5, wherein the two phases are separated by an increase in temperature due to a disease, and enzymatic degradation proceeds from the gel surface. 7. The biodegradable polymer constituting the three-dimensional network, wherein the constituent amino acids are alanine, valine, leucine, isoleucine, methionine, proline, phenylalanine, tryptophan, aspartic acid, glutamic acid, glycine, serine, threonine, Tyrosine, cysteine, lysine, arginine, oligopeptide chain consisting of any one or more of histidine, or dextran as a constituent polysaccharide, hyaluronic acid, chitin, chitosan, alginic acid, chondroitin sulfate, starch, oligosaccharide chain consisting of pullulan, The temperature-responsive biodegradable polymer according to any one of claims 1 to 6, wherein each molecular weight before forming the three-dimensional network structure is 500 to 1,000,000. 8. The temperature-responsive biodegradable polymer according to claim 1, wherein a water-soluble polymer that is non-degradable in vivo is used as a part of its constitution. 9. The temperature-responsive biodegradable polymer according to claim 8, wherein the non-biodegradable water-soluble polymer is a polyether or a polyether ester. 10. A non-degradable water-soluble polymer having a molecular weight of 500-10000, a biodegradable site contained in its molecular chain, a repeating unit of 1-5, and a constituent amino acid. As an alanine, valine, leucine, isoleucine, methionine, proline, phenylalanine, tryptophan, aspartic acid, glutamic acid, glycine, serine, threonine, tyrosine, cysteine, lysine, arginine, oligopeptide chain consisting of one or more of histidine, or 10. The high temperature-responsive biodegradable biodegradable composition according to claim 8 or 9, wherein the repeating unit is 1-5, and the polysaccharide has an oligosaccharide chain composed of dextran, hyaluronic acid, chitin, chitosan, alginic acid, chondroitin sulfate, starch, and pullulan. molecule.