JPH06206832A - Polymeric carrier - Google Patents

Abstract

PURPOSE:To provide such a polymeric carrier that, in binding a hydrophobic substance to the polyamino acid structural segment of a block copolymer, undesirable binding to this copolymer can be avoided, thus having high solubility and excellent in micelle-forming ability and to be used for carrying medicines. CONSTITUTION:The polymeric carrier consisting of a block copolymer having structure of formula I (R1 is H or lower alkyl; R2 is binding group; R3 is methylene or ethylene; R4 is lower alkyl or aromatic hydrocarbon; n is 5-1000; m is 2 300; x is 0-300; where, x<m). The compound of the formula, e.g. a compound of formula II, can be obtained by the following process: from a compound of formula III and a compound of formula IV, a compound of formula V is produced, and via a compound of formula V and a compound VI, successively. Another version of the polymeric carrier is a block copolymer (or a salt thereof) where a hydrophobic substance has been bound to, through reaction with, the carboxyl group of the compound of the formula I; this block copolymer (salt) is used as a polymeric carrier for medicine carriers excellent in micelle-forming ability. Use of the compound of the formula I in obtaining the latter block copolymer can prevent side reactions, thus facilitating the synthesis of the latter flock copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer carrier which can be used for carrying a drug.

[0002]

2. Description of the Related Art Micelle-forming amphipathic block copolymers are known, but in many cases, the structures are often unclear, and many side-reactants are generated due to the reaction between the block copolymers in the production process. In some cases, a drug carrier having the expected structure could not be obtained.

[0003]

SUMMARY OF THE INVENTION The present invention provides a polymeric carrier capable of avoiding an undesired bond between block copolymers when a hydrophobic substance is bonded to the polyamino acid structural portion of the block copolymer. Another object of the present invention is to provide a polymer carrier which is a drug carrier having a high solubility in which a hydrophobic substance is bound to the polymer carrier and which has an excellent micelle forming ability.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the problems in producing conventional micelle-forming amphiphilic block copolymers, and as a result, have found that block copolymers having a specific structure When binding a hydrophobic substance to the polymer, by modifying the terminal amino group of the block copolymer beforehand, it is possible to prevent the block copolymers from binding to each other, and micelle-forming drug delivery with improved solubility The present invention was completed by finding that the body was obtained.

That is, the present invention provides (1) a polymer carrier comprising a block copolymer having the structure of formula (1) or a salt structure thereof,

[0006]

[Chemical 2]

(Wherein R ₁ represents a lower alkyl group or hydrogen, R ₂ represents a bonding group, R ₃ represents a methylene group or an ethylene group, R ₄ represents a lower alkyl group such as a methyl group or an ethyl group. Alternatively, it represents an aromatic hydrocarbon group such as a phenyl group, n is 5 to 1,000, m is 2 to 300, and x is 0 to 3.
Although an integer of 00 is shown, x is not larger than m. ) (2) A block carrier in which a hydrophobic substance reacts with and binds to a carboxyl group of the formula (1) of the above (1) or a salt thereof to form a drug carrier having excellent micelle forming ability. Molecular carrier, (3) Polymer carrier according to (1) or (2) above, wherein R ₁ is a methyl group, (4) Above (1), (2) wherein R ₂ is an alkylene group having 2 to 4 carbon atoms. ) Or (3), and (5) the polymer carrier described in (1), (2), (3) or (4) above, wherein R ₄ is a methyl group.

According to the present invention, when binding a hydrophobic substance to a carboxyl group of a polymer carrier, an undesired binding reaction between the polymer carriers can be avoided, and as a result, micelle forming ability with high solubility can be achieved. An excellent drug carrier can be obtained.

The present invention will be described in detail below.

Examples of the salt include alkali metal salts such as sodium salt and potassium salt, and are not particularly limited.

The molecular weight of the polymer carrier of the present invention is not particularly limited as long as it is water-soluble, but preferably 1000.
˜100,000, particularly preferably 5,000 to 50,000
Is. The ratio of the polyethylene glycol structure part to the polyamino acid structure part in the block copolymer is not particularly limited as long as the water solubility of the polymer carrier is maintained, but preferably 1: 0.1 to 10 (weight ratio), particularly preferably Is 1: 0.
It is 2-5 (weight ratio).

In the polymer carrier of the above formula (1), R ₁
Represents a lower alkyl group or hydrogen, with a methyl group being preferred. R ₂ is not particularly limited as long as it does not impair the water solubility of the polymer carrier of the present invention, and a compound that forms a polyethylene glycol structural portion when forming a polyamino acid structural portion at the end of the polyethylene glycol structural portion. The structure corresponding to the method and compound used to convert the terminal of the compound into a structure suitable for the formation is taken, and for example, a methylene group (—CH ₂ —), an ethylene group (—
CH ₂ CH ₂ —), propylene group (—CH (CH ₃ ) C
H ₂ -), trimethylene group (-CH ₂ CH ₂ CH
₂ -), isobutylene group _{(-CH 2 CH (CH 3)} CH
Examples include alkylene groups having 1 to 8 carbon atoms, such as _2- ), preferably 2 to 4 carbon atoms, but are not particularly limited.

R ₄ is not particularly limited as long as it does not impair the water solubility of the polymer carrier, and examples thereof include a lower alkyl group and a phenyl group, with a methyl group being particularly preferred.
Further, n is 5 to 1,000, preferably 15 to 4
00 and m is 2 to 300, preferably 10
˜100 and x is 0 to 300, preferably 0 to 100.

The polymer carrier can be manufactured by various methods. For example, it can be manufactured as follows. That is, the terminal of the compound that constitutes the polyethylene glycol structure portion is modified as necessary. This modification can be performed by a known method. For example, as a method of converting a hydroxyl group into an amino group, a method of reacting ethyleneimine, Michael addition of acrylonitrile or methacrylonitrile, and then reduction of the nitrile group to convert into an amino group. The method can be carried out by substituting a halogen group for the hydroxyl group and then reacting it with an alcoholamine such as ethanolamine, or by directly converting the hydroxyl group into a nitrile group and then reducing and converting it into an amino group. A block copolymer is obtained by reacting a compound that constitutes the polyethylene glycol structural portion or a modified one of its terminals with a monomer of glutamic acid, aspartic acid or a derivative thereof.

After that, various protective groups are introduced into the amino group in the block copolymer for modification. Introduction of a protecting group to an amino group can be carried out according to a known method, for example, a method by acylation using an acid halide such as acetyl chloride or an acid anhydride such as acetic anhydride, A method of generating a Schiff base in the reaction and then reducing the Schiff base, a method of alkylation using an alkyl halide, a method of adding a compound having a double bond to an amine,
Examples thereof include a method by a ring-opening addition reaction using an epoxy compound.

Examples of the protecting group for modifying the amino group include various groups such as methyl group, ethyl group, propyl group, acetyl group and benzoyl group which can be introduced by a known method.

After that, for those having a protecting group in the carboxyl group, the protecting group is removed to obtain the polymer carrier of the above (1). The protecting group can be removed by an alkali method, an acid method or a reduction method. As the alkaline substance used in the alkaline method, normal alkaline substances such as caustic soda, caustic potash, hydrazine and ammonia can be used. As the acidic substance used in the acid method, a usual acidic substance such as trifluoromethanesulfonic acid, methanesulfonic acid, trifluoroacetic acid, acetic acid, formic acid, hydrofluoric acid, hydrobromic acid, and hydrochloric acid can be used. . Further, in order to prevent side reactions, anisole, thioanisole, m-cresol, o-cresol and the like can be added. As the reduction method, a general method such as a catalytic reduction method or a catalytic hydrogen transfer reduction method can be used. By binding a hydrophobic substance to the polymer carrier of (1) thus obtained, a micelle-forming drug carrier (polymer carrier of (2)) can be obtained.

Examples of the hydrophobic substance (1) that reacts with the carboxyl group of the polymer carrier include aromatic amines, aliphatic amines, aromatic alcohols, aliphatic alcohols, aromatic thiols, and aliphatic thiols. However, drugs such as adriamycin, daunomycin and etoposide can also be used as the hydrophobic substance. These hydrophobic substances are bonded to the block copolymer by reacting with a carboxyl group and forming an ester bond or an amide bond. These reactions can be carried out according to a conventional method such as known esterification or amidation.

For example, when a hydrophobic substance is bound to the polymer carrier of (1) above by an amide bond, the reaction can be carried out according to a conventional method known as a peptide bond forming method.
For example, an acid halide method, an acid anhydride method, a coupling method and the like can be used, but a coupling method using a condensing agent is preferable. As the condensing agent, 1-ethyl-3- (3-
Dimethylaminopropyl) carbodiimide (EDC),
1-Ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC.HCl), dicyclohexylcarbodiimide (DCC), carbonyldiimidazole (CDI), 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroxyquinoline (EEDQ), diphenylphosphoryl azide (DPPA) and the like can be used. The condensing agent is preferably used in an amount of 0.5 to 20 times by mole, and particularly preferably 1 to 10 times by mole with respect to the hydrophobic substance. At this time, N-hydroxysuccinimide (HO
NSu), 1-hydroxybenzotriazole (HOB
t), N-hydroxy-5-norbornene-2,3-dicarboxylic acid imide (HONB) and the like may coexist.

The amount of the hydrophobic substance used is not particularly limited, but is usually 0.1 to 2 mol per 1 equivalent of the carboxyl group of the polymer carrier (1).

The condensation reaction is preferably carried out in a solvent, and examples of the solvent include N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), dioxane, tetrahydrofuran (THF), water and a mixed solvent thereof. Various materials can be used and are not particularly limited. Although the amount of the solvent used is not particularly limited, it is usually used in an amount of 1 to 500 times by weight based on the polymer carrier of (1).

The condensation reaction is preferably performed at -10 to 40 ° C, particularly preferably at -5 to 30 ° C. It is sufficient to carry out the reaction for 2 to 48 hours.

For example, in the polymer carrier of the above (2) obtained as described above, the hydrophobic substance is the above (1).
It is preferable that at least 1% of all the carboxyl groups of the polymer carrier react with and bond with the carboxyl groups, especially 5%.
It is preferable that they react with and bond to the above-mentioned carboxyl groups.

The following is an example of a polymer carrier which is a block copolymer composed of a polyethylene glycol structure part and a polyaspartic acid structure part, and in which the amino group at the terminal of the polyaspartic acid structure part is modified with an acetyl group. Describe the method in detail.

The synthesis of this polymer carrier is carried out by using β-benzyl-L-aspartate-N-carboxylic acid anhydride (BLA-NCA), which has a methoxy group at one end, as shown in the following reaction formula. Of polyethylene glycol (PEG-NH ₂ ) having a 3-aminopropyl group at one end thereof (preferably a molecular weight of 250 to 20,000) as an initiator, and a solvent such as dimethylformamide, dimethylsulfoxide, dioxane, chloroform, tetrahydrofuran, acetonitrile and the like. Ring-opening polymerization in a polyethylene glycol-poly (β-benzyl-L-aspartate) block copolymer (PEG-PBLA) to obtain acetic anhydride and a tertiary amine such as pyridine and triethylamine. Is added to modify the terminal amino group with an acetyl group. Ru-poly (β-benzyl-L-aspartate) block copolymer N-acetylated product (PE
G-PBLA-Ac) is obtained. This PEG-PBLA-
The benzyl ester of Ac is hydrolyzed to obtain a polyethylene glycol-polyaspartic acid block copolymer N-acetylated product (PEG-P (Asp.)-Ac).
Further, modification of the terminal amino group gives a polyethylene glycol-poly (β-benzyl-L-aspartate) block copolymer (PEG-PBLA), and then this PEG
After hydrolyzing the benzyl ester of -PBLA to obtain a polyethylene glycol-polyaspartic acid block copolymer (PEG-P (Asp.)), Acetic anhydride and a tertiary amine such as triethylamine are added to add a terminal amino group. Of the polyethylene glycol-polyaspartic acid block copolymer N-acetylated product (PE
GP (Asp.)-Ac) can also be obtained.

[0026]

[Chemical 3]

(In the formula, n is 5 to 1,000 and m is 2 to 3
00 and x represent an integer of 0 to 300, but x is not larger than m. ).

The polymer carrier of (1) of the present invention is to obtain a drug carrier having high solubility by preventing undesired bonds between the polymer carriers when binding a hydrophobic substance.

[0029]

EXAMPLES The present invention will be described in detail with reference to examples.

Example 1 5.7 g of β-benzyl-L-aspartate-N-carboxylic acid anhydride (BLA-NCA) is dissolved in 60 ml of N, N'-dimethylformamide (DMF). _{3. One} end methoxy group, one end 3-aminopropyl group polyethylene glycol (PEG-NH ₂ ) (molecular weight 5,100) 4.
0 g was dissolved in 40 ml of DMF, and the solution was BLA-N.
Add to CA solution. The obtained solution was polymerized for 40 hours while keeping it at 35 ° C. After confirming the completion of the polymerization reaction by HPLC analysis, 50 ml of acetic anhydride and 2.5 of pyridine
g and react at room temperature for 2 hours. The reaction mixture was added dropwise to 2 liters of isopropyl ether, and the precipitated polymer was collected by filtration, washed with isopropyl ether, and dried in vacuum to obtain polyethylene glycol-poly (β-benzyl-L-aspartate) block copolymer N-. 8.03 g of acetylated product (PEG-PBLA-Ac) was obtained.
H-NMR (CDCl ₃ + CH ₃ OD) analysis gave N-
From the peak ratio of the methyl proton of the acetyl group (2.01 ppm) and the methyl proton of the methoxy group at one end (3.35 ppm), it was confirmed that the amino group was completely modified with the acetyl group.

7.0 g of PEG-PBLA-Ac was added to 0.
The benzyl ester is hydrolyzed at room temperature while suspending in 5N sodium hydroxide. After PEG-PBLA-Ac was dissolved, the pH was acidified with acetic acid, and the dialysis membrane (molecular weight cut off =
Dialysis in water with 1,000). The solution in the membrane was freeze-dried to obtain a polyethylene glycol-polyaspartic acid block copolymer N-acetylated product (PEG-P (A
sp. ) -Ac) (4.44 g, yield 79%) was obtained. H
-NMR (D ₂ O) analysis showed that the amino group was completely modified with an acetyl group based on the peak ratio of the methyl proton of the N-acetyl group (1.75 ppm) and the methyl proton of the methoxy group at one end (3.22 ppm). I confirmed that.

Example 2 5.7 g of β-benzyl-L-aspartate-N-carboxylic acid anhydride (BLA-NCA) is dissolved in 60 ml of N, N'-dimethylformamide (DMF). _{3. One} end methoxy group, one end 3-aminopropyl group polyethylene glycol (PEG-NH ₂ ) (molecular weight 5,100) 4.
0 g was dissolved in 40 ml of DMF, and the solution was BLA-N.
Add to CA solution. 40 while maintaining the polymerization solution at 35 ° C
Polymerized for hours. After confirming the completion of the polymerization reaction by HPLC analysis, the reaction mixture was added dropwise to 2 liters of isopropyl ether, and the precipitated polymer was collected by filtration, washed with isopropyl ether, and vacuum dried to obtain polyethylene glycol-poly (β -Benzyl-L-aspartate) block copolymer (PEG-PBLA) 7.9
9 g (yield 92.1%) was obtained. PEG-PBLA7.
The benzyl ester is hydrolyzed at room temperature while suspending 0 g in 0.5 N sodium hydroxide. After the PEG-PBLA is dissolved, the pH is acidified with acetic acid, and dialyzed in water using a dialysis membrane (fraction molecular weight = 1,000). The solution in the membrane was freeze-dried to obtain a polyethylene glycol-polyaspartic acid block copolymer (PEG-P (Asp.)).
4.44 g (yield 79%) was obtained. PEG-P (As
p. ) 1.0 g is suspended in 20 ml of acetic anhydride, 2 ml of triethylamine is added, and the mixture is reacted at room temperature for 10 minutes. After the reaction
The pH was made acidic with acetic acid and the dialysis membrane (molecular weight cutoff = 1,00
Dialyse in water with 0). The solution in the membrane was freeze-dried to obtain a polyethylene glycol-polyaspartic acid block copolymer N-acetylated product (PEG-P (Asp.)).
-Ac) 0.54 g was obtained. By H-NMR (D ₂ O) analysis, the methyl proton of the N-acetyl group (1.75 pp
m) and the methyl proton of the methoxy group at one end (3.22 p
It was confirmed from the peak ratio with pm) that the amino group was completely modified with an acetyl group.

Example 3 Polyethylene glycol-polyaspartic acid block copolymer N-acetylated product (PEG-P) obtained in Example 1
195 mg of (Asp.)-Ac) is dissolved in 0.5 ml of water. 54 mg of stearylamine is suspended in 5 ml of DMF, and an (PEG-P (Asp.)-Ac) aqueous solution is added. To this mixed solution, 72 μl of 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDC), N
28 mg of -hydroxysuccinimide (HONSu) was added and reacted at room temperature for 24 hours. The reaction mixture was diluted with a dialysis membrane (molecular weight cut-off = 12,000) to a value of 0. Dialyze for 3 hours in 1M sodium acetate buffer (pH 4.5). After dialysis, the deposited precipitate was filtered, and the filtrate was used as ADVANTEC U
Unreacted stearylamine and other low molecular weight substances are removed by ultrafiltration with an ultrafiltration membrane of K-50 (molecular weight cut off = 50,000). Repeated washing and concentration with a molecular weight of 50,0
A stearylamine conjugate having a micellar state of 00 or more was obtained. Lyophilization was performed to obtain 201 mg of stearylamine-bonded PEG-P (Asp.)-Ac. It was confirmed by H-NMR analysis that stearylamine was bound to 5% of the carboxyl groups of PEG-P (Asp.)-Ac. Even when the freeze-dried product was dissolved in water, the micelles were in good condition and showed high water solubility.

[0034]

When the polymer carrier of (1) of the present invention is used, it is possible to prevent side reactions when binding a hydrophobic substance to its carboxyl group, and it is excellent in micelle forming ability with high solubility. The drug carrier of (2) can be easily obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunori Kataoka 1083-4 Omuro, Kashiwa City, Chiba Prefecture 141-9, Kashiwa Village, Mitsuo Okano 6-12-12 Kunifudai, Ichikawa City, Chiba (72) Invention Person Yasuhisa Sakurai 3-17-6, Eifuku, Suginami-ku, Tokyo (72) Inventor ▲ Takashi Fuji, 45-3 Shimokawa-cho, Maebashi-shi, Gunma Prefecture (72) Shigeto Fukushima 239 Iwahana-cho, Takasaki-shi, Gunma Prefecture (72) Inventor Mekumi Machida 36-3 Uenodai, Fukaya-shi, Saitama Prefecture (72) Inventor Yoshimi Yamada 1393-2 Shinmachi, Tano-gun, Gunma Prefecture (72) Ryuji Uehara 239 Iwahana-cho, Takasaki-shi, Gunma Prefecture

Claims (5)

[Claims] 1. A polymer carrier comprising a block copolymer having the structure of formula (1) or a salt structure thereof. [Chemical 1] (In the formula, R ₁ represents a lower alkyl group or hydrogen, R ₂ represents a bonding group, R ₃ represents a methylene group or an ethylene group, and R ₄ represents a lower alkyl group or an aromatic hydrocarbon group. Is 5-1,000, m is 2-300, and x is 0
An integer of 300 is shown, but x is not larger than m. ) 2. A drug carrier having excellent micelle-forming ability, which is composed of a block copolymer or a salt thereof in which a hydrophobic substance reacts with and binds to a carboxyl group of the formula (1) of claim 1. Molecular carrier. 3. The polymer carrier according to claim 1, wherein R ₁ is a methyl group. 4. The polymer carrier according to claim 1, 2 or 3, wherein R ₂ is an alkylene group having 2 to 4 carbon atoms. 5. The method according to claim 1, wherein R ₄ is a methyl group.
Alternatively, the polymer carrier according to item 4.