JPH0546328B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a biodegradable copolymer complex that provides a sustained release function to a drug. [Prior Art] Polymers such as lactic acid and glycolic acid are biodegradable and bioabsorbable, and have thus far been applied to biodegradable medical materials such as surgical sutures. In addition, in recent years, drug release control systems (DDS) have been developed to control drug administration to living organisms.
Various studies are being carried out as a base material for the delivery system. This kind of DDS base has the function of releasing a certain amount of drug into the body over a predetermined period of time. A base of pure ingredients is desired. As conventionally known bases, homopolymers such as lactic acid and glycolic acid are known. However, since homopolymers such as lactic acid and glycolic acid are desired to have high molecular weight products, polymerization is usually carried out using lactide or glycolide as a raw material and using a catalyst. Therefore, in this method, it is necessary to remove the catalyst remaining as an impurity, and an organic solvent is used for removing the catalyst, but a new problem arises, that is, the remaining organic solvent. In addition, due to its high molecular weight, the base is solid,
Therefore, when mixing this and a base, it is necessary to melt the base at a high temperature, which causes problems such as denaturation and decomposition of the drug. On the other hand, a method is known in which lactic acid and glycolic acid are used as raw materials, and dehydration polycondensation is performed in the absence of a catalyst to obtain a low molecular weight homopolymer. It is possible to lower the drug and drug decomposition is suppressed. However, homopolymers of lactic acid and glycolic acid, as well as the above-mentioned high molecular weight homopolymers, are generally crystalline and have the following problems as DDS bases for living organisms. First, such crystalline polymers exhibit non-uniform degradability in vivo. This is because a crystalline polymer consists of a crystalline part and an amorphous part,
This is due to the fact that the crystalline portion is much less biodegradable than the amorphous portion. Additionally, drugs are generally more dissolved or dispersed in the amorphous portion than in the crystalline portion, and therefore DDS
When this is used as a base, the amorphous part decomposes first, and even after drug release is complete, a crystalline part that does not contain the drug remains, and this phenomenon is not desirable as a DDS base. It is. In addition, it is possible to some extent to reduce the crystallinity by lowering the molecular weight, but in this case it is generally necessary to keep the molecular weight to several hundred or less.
However, in this case, the acid concentration at the end of the polymer becomes high, causing problems such as inflammation when it comes into contact with living organisms, and biodegradation is too rapid, so it has almost no function as a sustained-release base. Become. In this way, it is desirable that the polymer used as a DDS base for living organisms is amorphous or has a low degree of crystallinity, and in this respect, homopolymers such as lactic acid and glycolic acid are usually used as DDS bases for living organisms. , it is not suitable for practical use. As a DDS base, a base made of a copolymer with a lactone such as lactic acid or glycolic acid is used as a DDS base to overcome the disadvantages in terms of sustained release control, especially of a base made of a homopolymer such as lactic acid or glycolic acid. It has been known. [HRKricheldorf, T. Mang and J.
M. Jonte, Macromolecules, 17 , 2173–2181
(1984)], [HRKricheldorf, T. Mang and J.
M.Jonte, Makromol.Chem., 186 , 955–976
(1985)] This base is produced by first synthesizing cyclic diesters glycolide and lactide obtained by depolymerizing oligomers of glycolic acid and lactic acid, and then reacting these cyclic diesters with lactones in the presence of a catalyst. It can be obtained by However, this base also has the problem of removal of the catalyst used, the problem of residual organic solvent used during removal, and furthermore, since the base is a high molecular weight substance, there is a risk of deterioration of the drug during high-temperature melt mixing with the drug. These problems have not been resolved, and the current situation is that an excellent DDS base for biological use has not yet been found. [Problems to be solved by the invention] In order to solve the above-mentioned problems, the present inventors have developed
This base is desired as a DDS base, has no side effects on living organisms, and can be applied to a wide range of applications without being restricted by problems of drug degradation or sustained release control. We conducted extensive research to obtain an excellent base material. [Means for solving the problem] As a result, lactic acid and/or glycolic acid and γ-
A copolymer with a specific composition and a number average molecular weight in the range of 500 to 5000 obtained by direct dehydration polycondensation of butyrolactone, δ-valerolactone and/or ε-caprolactone in the absence of a catalyst can be used as a DDS base for biological use. They have discovered that the invention is excellent, and have completed the present invention. That is, the present invention combines lactic acid and/or glycolic acid with γ-butyrolactone, δ-valerolactone and/or
or direct dehydration polycondensation with ε-caprolactone,
The molar ratio of lactic acid and/or glycolic acid (A) to γ-butyrolactone, δ-valerolactone and/or ε-caprolactone (B) is 20/80 to 90 as (A)/(B) molar ratio The present invention relates to a biodegradable copolymer composite in which a drug is mixed with a biodegradable copolymer having a number average molecular weight of 500 to 5000 and a drug with a sustained release function. [Function] The present invention will be explained in more detail below. The present invention first involves combining lactic acid and/or glycolic acid with γ-butyrolactone, δ-valerolactone and/or
Alternatively, a biodegradable copolymer is obtained by direct dehydration polycondensation with ε-caprolactone. There are no particular restrictions on the type of lactic acid, including D-form,
It may be either L-form or DL-form. Regarding the proportions of these monomers used, the copolymer obtained after direct dehydration polycondensation contains lactic acid and/or
or glycolic acid (A) and γ-butyrolactone, δ-
Valerolactone and/or ε-caprolactone (B)
That is, the molar ratio of (A)/(B) is 20/80.
Use in a ratio ranging from ~90/10. In this case, if this molar ratio exceeds 90/10 and the amount of lactic acid and glycolic acid increases, the degree of crystallinity will increase and a mixture of this substance and the drug will form a non-uniform matrix. As a result, the release rate of the drug becomes too high, making it undesirable as a drug. On the other hand, when the molar ratio is less than 20/80 and the amount of lactones such as δ-valerolactone increases, the copolymer obtained after the reaction has a high degree of crystallinity, similar to homopolymers such as lactic acid and glycolic acid. This is undesirable because the sustained release properties of the base material are significantly reduced. The direct dehydration polycondensation reaction of lactic acid and/or glycolic acid with γ-butyrolactone, δ-valerolactone and/or ε-caprolactone can be carried out by introducing nitrogen gas into the raw material liquid without a catalyst or by
2-30 at a temperature of 150-250℃ under reduced pressure of about 100mmHg
The reaction may be carried out by heating for a certain period of time, but the conditions are not particularly limited to these. In the present invention, it is possible to carry out the reaction without a catalyst, so there is no need to remove the catalyst, and the resulting copolymer does not contain impurities such as organic solvents and is suitable for biological use.
It is preferable as a DDS base. A particularly important point in the present invention is that the lactic acid and/or glycolic acid obtained in this way and γ-butyrolactone, δ-valerolactone and/or ε-
The number average molecular weight of the copolymer with caprolactone is
The number should be between 500 and 5000. If the molecular weight of this copolymer falls outside this range,
When it is less than 500, the release of the drug added and mixed in the latter stage becomes extremely rapid, and it has no function as a sustained release base at all. Conversely, the number average molecular weight is 5000
When the amount exceeds 1, the resulting copolymer becomes rubbery and difficult to mix with the drug. The copolymer after polycondensation differs depending on the component composition of the raw materials, but since it is usually in a paste form, the drug can be added and mixed in the latter stage at room temperature or under slight heating. In the present invention, a complex is then obtained by mixing such a biodegradable copolymer and a drug.
The types of drugs used are not particularly limited, and include hormones, antihistamines, antihypertensives, vasodilators,
Blood vessel reinforcing agent, stomachic digestive agent, intestinal regulation agent, contraceptive agent, disinfectant for external skin, agent for parasitic skin diseases, anti-inflammatory agent, analgesic agent, choleretic agent, antirheumatic agent, cardiac agent, hemorrhoid treatment agent, constipation treatment agent Drugs such as vitamins, various enzyme preparations, vaccines, antiprotozoal agents, interferon inducers, anthelmintics, fish disease drugs, agricultural chemicals, plant hormones such as auxin, gibberellin, and cytokinin abscisic acid, and insect pheromones can be used. Further, these drugs may be either natural products or synthetic products. Next, an example of manufacturing a complex of the present invention obtained by mixing a biodegradable copolymer and these drugs will be described. For example, lactic acid and/or glycolic acid and γ-
Butyrolactone, δ-valerolactone and/or ε-caprolactone are directly dehydrated and polycondensed to form a molar ratio of lactic acid and/or glycolic acid (A) and γ-butyrolactone, δ-valerolactone and/or ε-caprolactone (B). A biodegradable copolymer with a ratio (A)/(B) molar ratio in the range of 20/80 to 90/10 and a number average molecular weight in the range of 500 to 5000 is appropriately selected and to a container, usually a fixed amount of the drug as described above, and thorough mixing. Furthermore, when it is necessary to heat and melt the copolymer, the copolymer may be melted and mixed while being heated to 100° C. or less directly, in a water bath, or in a constant temperature bath. The biodegradable copolymer complex obtained in this manner, which has a sustained-release function on the drug of the present invention, has excellent sustained-release properties, contains no impurities, has no side effects on living bodies, and is in a paste-like form. Therefore, it is easy to mold and is an excellent biological DDS composite that can be applied to a wide range of applications. Specific examples of its usage are as follows. A method in which a flexible container 7 with a pointed tip is filled with the complex 5, and when used, a part of the living body is incised and injected (see Figure 8).The complex 5 is applied to a sheet-like material 6, and a poultice is applied. (See Fig. 9) A method consisting of a disposable type 8 syringe with a shape that allows injection and insertion by filling the composite 5 into a tubular container such as a Teflon tube and extruding it (Fig. 10) Also, when sterilizing these items, it is possible to sterilize them using a radiation source, and in that case, it is ideal to select a radiation source that can sterilize the inside of the complex. It is. Therefore, γ-ray sources and β-ray sources with strong penetrating power such as ⁶⁰ Co and ¹³⁷ Cs are used, and the irradiation dose is 5×10 ⁵ rad.
~5×10 ⁶ rad is suitable. [Examples] The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. Moreover, all percentages indicate weight % unless otherwise specified. Examples 1-4 L-lactic acid (90%) and δ-valerolactone (100%)
%) mixture [L-lactic acid/δ-valerolactone=
30/70 (molar ratio)] 70g was placed in a 200ml reaction vessel,
While introducing nitrogen gas into the mixture at a rate of 200 ml/min, at 200°C for 2 hours (Example 1), 4 hours (Example 2), 8 hours (Example 3), 16 hours (Example 4) Made it react. 100mg of these copolymers contain calcitonin (an osteoporosis treatment drug) as a drug.
1 mg of was added and mixed until homogeneous to obtain a copolymer composite of the present invention. The physical properties and in vivo degradation rates of these complexes were measured. In order to determine the in vivo decomposition rate, the complex was first filled into an ointment container (internally treated with Teflon), and then injected into the lower part of the rat's back skin, which was incised. Next, the rats were sacrificed one week after implantation of the complex, the amount of the remaining complex was measured, and the degradation rate was calculated from the injection amount. These results are shown in Table 1. For comparison, 70 g of the mixture of L-lactic acid and δ-valerolactone [L-lactic acid/δ-valerolactone = 30/70 (molar ratio)] was similarly placed in a 200 ml reaction vessel, and the mixture was heated at 200 ml/min. While introducing nitrogen gas into the mixture at a certain rate, the reaction was carried out at 200℃ for 1 hour.
A copolymer with a number average molecular weight of 300 was obtained. (Comparative Example 1) For further comparison, a high molecular weight copolymer of L-lactic acid and δ-valerolactone was obtained. The method involves adding 5 g of a mixture of L-lactide (100%) and the above-mentioned δ-valerolactone [L-lactic acid/δ-valerolactone = 30/70 (molar ratio) equivalent value] to 20 ml.
0.1% of tin octoate was added as a catalyst based on the total weight of L-lactide and δ-valerolactone, the container was sealed, and freeze-degassing was repeated three times, followed by 1×10 ^- The reaction was carried out at 200° C. for 4 hours under reduced pressure of ⁴ mmHg. The obtained copolymer was dissolved in chloroform and then precipitated in a large amount of methanol, followed by vacuum drying at 30°C to obtain a rubbery copolymer at room temperature. (Comparative Example 2) Regarding the copolymers obtained in Comparative Examples 1 and 2, calcitonin was added as a drug and mixed in the same manner as in Examples 1 to 4. The physical properties and in
The in vivo degradation rate was measured. The results are shown in Table 1.

[Table] Examples 5 to 8 L-lactic acid (90%) and δ-valerolactone (100%)
%) mixing molar ratio (L-lactic acid/δ-valerolactone molar ratio) is 20/80 (Example 5) and 50/50, respectively.
(Example 6), 70/30 (Example 7), and 90/10 (Example 8), and 50 g of the mixture was placed in each 200 ml reaction vessel. For comparison, a similar test was conducted under the following conditions. Regarding 50 g of L-lactic acid and δ-valerolactone mixed molar ratio (L-lactic acid/δ-valerolactone molar ratio) of 10/90 (Comparative Example 3),
For 70 g of L-lactic acid (90%) to obtain a homopolymer of L-lactic acid (comparative example 4), 60 g of δ-valerolactone (100%) and 10 g of water to obtain a homopolymer of δ-valerolactone. (Comparative Example 5), these were placed in each 200 ml reaction container in the same manner. These solutions prepared as Examples and Comparative Examples were reacted at 200° C. for 10 hours while nitrogen gas was introduced at a rate of 200 ml/min to obtain copolymers and homopolymers. 1 mg of calcitonin as a drug was added to 100 mg of these polymers, and the mixture was mixed until homogeneous to obtain a copolymer complex of the present invention. The physical properties and in vivo degradation rates of these complexes were measured. Incidentally, the in vivo decomposition rate was determined by the following method.
First, a predetermined amount of the composite was placed in a Teflon tube (inner diameter 2
mmφ, length 50 mm) and molded at 70° C. under a pressure of 100 Kg/cm ² . Through this process, the composite filled in the Teflon tube has an inner diameter of 2 mmφ.
It became a rod shape. Next, in this state, the pointed end of the tube was inserted into the lower part of the rat's back skin, and the composite was inserted in the injection state using a stainless steel rod-shaped extruder. Two weeks after implantation of the complex, the rats were sacrificed.
The remaining amount of the complex was measured and the decomposition rate was calculated from the injection amount. These results are shown in Table 2.

[Table] Examples 9 to 11 In place of L-lactic acid in Example 4, 90% D-lactic acid (Example 9), 90% DL-lactic acid (Example 10) and 100%
A copolymer was similarly synthesized using glycolic acid (Example 11). 1 mg of calcitonin as a drug was added to 100 mg of the obtained copolymer, and the mixture was mixed until homogeneous. The physical properties of the composite thus obtained were measured and the results are shown in Table 3. Also in rats
The in vivo decomposition rate was measured at predetermined weekly intervals, and changes in the decomposition rate are shown in Figure 1.

[Table] Examples 12-13 100% in place of δ-valerolactone in Example 7
Copolymers were similarly synthesized using γ-butyrolactone (Example 12) and 100% ε-caprolactone (Example 13). The properties of the obtained copolymers were examined by X-ray diffraction, and as a result, they were all amorphous. 1 mg of calcitonin as a drug was added to 100 mg of these copolymers and mixed until homogeneous. The physical properties of the composite thus obtained and the in vivo decomposition rate one week after implantation in rats were measured, and the results are shown in Table 4.

[Table] Examples 14 to 19 45 mg of a copolymer (L-lactic acid/δ valerolactone molar ratio 87/13) synthesized in the same manner as in Example 8 and natural luteinizing hormone releasing hormone (hereinafter referred to as “luteinizing hormone releasing hormone”) as a drug. It is abbreviated as LH-RH.The amino acid sequence of natural LH-RH is pGlu-His-Trp-Ser-Tyr-
Gly−Leu−Arg−Pro−Gly−NH ₂ )
mg (Example 14), 5 mg of [Gly-OH ¹⁰ ]-LH-RH (Example 15), which is a similar LH-RH substance, and 5 mg of [D-Ala ⁶ ]-LH-RH (Example 15). example
16), 5 mg of [D-Phe ² , D-Ala ⁶ ]-LH-RH
(Example 17), [Ac-D-Pcl-Phe ^1,2 , D-Trp ³ ,
5 mg of D-Arg ⁶ , D-Ala ¹⁰ ]-LH-RH (Example 18), 5 mg of [des-Gly ¹⁰ , D-Leu ⁸ ]-LH-RH
mg (Example 19) were respectively placed in glass test tubes, and mixed and stirred at a temperature of 70°C for 3 minutes. The copolymer and drug melted quickly under those conditions, resulting in a homogeneous complex. After cooling the composite, it was filled into a disposable type Teflon tube (inner diameter 2 mmφ, length 60 mm) and heated to a temperature of 100 Kg/cm 2 under a pressure of 100 kg/cm ² .
Molding treatment was carried out at 50°C for 2 minutes. Through this process,
The composite filled in the Teflon tube has an inner diameter of 2 mm.
It became a rod shape with a diameter of φ and a length of 15 mm. In order to sterilize this molded composite, it was stored at -78℃ (dry ice-methanol) in a nitrogen atmosphere.
γ-rays from a ⁶⁰ Co source were irradiated at a dose rate of 1×10 ⁶ R/h for 3 hours at a temperature of . The in vivo release amount of the drug (physiologically active substance) from the complex of the present invention obtained by the above treatment was measured. The method involved administering the complex to Wistar rats (male, body weight 400 kg).
The tip of a disposable type Teflon tube was inserted into the lower back skin of ~500 g), and the entire amount of the filled composite was extruded and inserted using a Teflon rod. After a predetermined period of time, the rats were sacrificed, the complexes were extracted, the amount of remaining drug was measured, and the drug release rate was calculated from the amount injected. In this way, the amount of drug released for each drug was measured at each predetermined period, and the results are shown in FIG. Furthermore, the pharmacological action of the drug (physiologically active substance) was calculated by calculating the weight of the ventral lobe of the prostate per 100 g of rat body weight (mg/
100gbw) and the results are shown in Figure 3. Example 20 1 g of a copolymer synthesized in the same manner as in Example 12 (L-lactic acid/γ-butyrolactone molar ratio 78/22) and estramustine as a drug.
100 mg of anticancer drug) was completely dissolved in 10 ml of methylene chloride. This methylene chloride solution containing the drug and copolymer was dropped into 200 ml of a 1% polyvinyl alcohol aqueous solution using a dropper while stirring at 400 rpm, and after the dropwise addition was completed, the solution was further stirred at room temperature for 24 hours.
By this operation, the complex of the present invention containing estramastine as a drug is formed into fine particles (30 to 50μ
m) became. This particulate composite was washed with water for several days, freeze-dried, and then subjected to animal experiments. In the animal experiment, 100 mg of the particulate complex was suspended or dispersed in 1 ml of physiological saline, and the entire amount was injected into the lower skin of the back of a rat using a syringe. The pharmacological action of the drug was determined by the weight of the ventral lobe of the prostate per 100g of rat body weight (mg/100gbw), and the results were reported in the fourth section.
Shown in the figure. Examples 21 to 26 1 g of a copolymer (L-lactic acid/ε-caprolactone molar ratio 69/31) synthesized in the same manner as in Example 13 and 100 mg of Cephalothin (antibiotic) as a drug (Example 21) , also 100 mg of Gentamicin (antibiotic)
(Example 22), Indacin (antipyretic agent)
(Example 23), 100 mg of Indomethacin (anti-inflammatory agent) (Example 23),
24), 100 mg of Phenobarbitone (cardiac drug) (Example 25), and 100 mg of Caffein (analgesic) (Example 26) were mixed while heating at a temperature of 80°C. These complexes were filled into dialysis cellophane tubes each sealed at one end using a syringe. An in vitro drug release test was conducted using the membrane diffusion method (see Figure 5), and the results are shown in Table 5.

[Table] Example 27 1 g of the copolymer synthesized in the same manner as in Example 13 and 0.1 g of [Ftoraful (anticancer drug)] were mixed. Using this complex of the present invention, in vivo
The blood concentration of ftorafur was measured. The method involved filling an enema-like container with the above complex, injecting the entire amount through the anus of a mongrel dog (weighing 10 kg), and measuring the blood concentration of ftorafur at predetermined intervals. The results are shown in Figure 6. Example 28 Using a complex of the present invention in which a copolymer synthesized in the same manner as in Example 13 was mixed with Estracyt (an anticancer drug), the blood concentration of Estracyt was measured in vivo. Method is 0.5 g of the above complex (estracyte
(equivalent to 50 mg) was filled into an enema-like container, and the entire amount was injected into the anus of a rabbit (weighing 4 kg), and the blood concentration of estracyte was measured at predetermined intervals. The results are shown in Figure 7. Examples 29-31 Synthesized in the same manner as Example 10 (DL-lactic acid/δ-
0.5 g of valerolactone molar ratio 30/70) copolymer (number average molecular weight 2200), 100 mg of calcitonin (Example 29) as a drug, and similarly 100 mg of Testosterone (hormone drug).
(Example 30), 100 mg of natural LH-RH (Example 31)
were mixed while heating each at a temperature of 80°C. These composites were applied to a cloth material and attached to the epidermis of the back of a hairless mouse (weighing 100 g). The mice were sacrificed at predetermined intervals, and the drug concentration in the mouse blood was measured. The results are shown in Table 6.

【table】 [Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the biodegradation rate of the copolymers of the composites of the present invention produced in Examples 9 to 11 and the period of in vivo implantation. Figure 2 shows an example
14 is a graph showing the relationship between the in-vivo release amount of the physiologically active substance of the composites of the present invention manufactured in Nos. 14 to 19 and the in-vivo implantation period. FIG. 3 is a graph showing the relationship between the pharmacological action of the hormones released from the composites of the present invention produced in Examples 14 to 19 (expressed by the weight of the ventral lobe of the prostate) and the period of in vivo implantation. Figure 4 shows an example
20 is a graph showing the relationship between the pharmacological action of the hormone released from the composite of the present invention prepared in Example 20 (expressed as the weight of the ventral lobe of the prostate) and the period of implantation in the living body. Fifth
The figure is a schematic diagram of an in vitro release test device using a membrane diffusion method used in Examples 21 to 26. 6th
7 and 7 are graphs showing the relationship between the pharmacological action of the hormone released from the composites of the present invention produced in Example 27 and Example 28 (expressed by the weight of the abdominal lobe of the prostate) and the period of implantation in the living body. It is. FIG. 8, FIG. 9, and FIG. 10 each show a specific example of an insertion tool for inserting the composite of the present invention into a living body. 1...Selection cellophane tube, 2...Sample, 3...Pump, 4...37℃ physiological saline (1000
ml), 5...composite, 6...sheet-like material, 7...
...Teflon-treated flexible container with a pointed tip, 8
...Syringe type disposable.

Claims (1)

[Claims] 1 Direct dehydration polycondensation of lactic acid and/or glycolic acid and γ-butyrolactone, δ-valerolactone and/or ε-caprolactone to produce lactic acid and/or glycolic acid (A), γ-butyrolactone, δ-valerolactone and/or Or the molar ratio with ε-caprolactone (B) is 20/80 to (A)/(B) molar ratio
90/10 range and number average molecular weight is 500
A biodegradable copolymer composite in which a drug is mixed with a biodegradable copolymer having a molecular weight of 5,000 to 5,000, and a drug is given a sustained release function.