JPH0196139A - Biodegradable copolymer complex making drug gradually releasable - Google Patents

Abstract

PURPOSE:To obtain the title copolymer which is used as a DDS base for living bodies with no side-effect and no limitation from view points of drug decomposition and release control, by direct dehydrative polycondensation of lactic acid and/or glycolic acid and gamma-butyrolactone. CONSTITUTION:A biodegradable copolymer is obtained by using (A) lactic acid and/or glycolic acid and (B) gamma-butyrolactone, delta-valerolactone and/or epsilon- caprolactone at a A/B molar ratio of 20/80-90/10 in a nitrogen atmosphere or under vacuum of 10-100mmHg at 150-250 deg.C for 2-30 hours. The copolymer is used as a base for DDS(drug discharge control system) and mixed with drugs to prepare a gradually releasable drug complex. The complex is applied to living bodies by pouring from cut opening or injection or spreading on the body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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 delivery systems (DDS) have been developed to control drug administration to living organisms.
Various studies are being conducted as base materials for em).

In this way, the DS 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, as homopolymers such as lactic acid and glycolic acid are desired to have high molecular weight products, they are usually made from lactide and glycolide as raw materials.
Polymerization is carried out 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 the organic solvent remains. In addition, because of its high molecular weight, the base is solid, and therefore, when mixing it with the base, it is necessary to melt the base at 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 the crystalline polymer consists of a crystalline portion and a non-quality portion, and the crystalline portion has much poorer biodegradability than the non-quality portion.

Additionally, drugs are generally dissolved or dispersed in the non-crystalline portion rather than the crystalline portion, so when this is used as a DDS base, the non-crystalline portion decomposes first and drug release is completed. Even after this, a crystalline portion that does not contain the drug remains,
This phenomenon is undesirable as a DDS base. 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 of poor quality or has a low degree of crystallinity. , it is not suitable for practical use.

As a DDS base, a base made of a copolymer of lactic acid, glycolic acid, etc. and lactones can be used as a DDS base to overcome the drawbacks 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. (H, R, Kr1
chcldorf, T., Mang and J., M.
, Jontc, Macromolcculcs,
17.2173-2181 (1984)), (
H, R, Kr1cheldorf, T, Hang
and J, M, Jontc, MakrorBol
, Chc[11,+ 186.955~97B (19
85)] This base can be obtained 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. Can be done. 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. The current situation is that these problems have not been resolved and 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 a base that is desired as a DDS base for living bodies, has no side effects on living bodies, and is capable of decomposing drugs. We have carried out extensive research in order to obtain an excellent base that can be used in a wide range of applications without any restrictions on sustained release control.

[Means for solving the problem] As a result, a product obtained by direct dehydration polycondensation of lactic acid and/or glycolic acid and γ-butyrolactone, δ-valerolactone and/or ε-caprolactone in the absence of a catalyst. What is the specific composition and the number average molecular weight is 500 to 5.00?
The present inventors have discovered that copolymers in the range of 0 are excellent as DDS bases for living organisms, and have completed the present invention.

That is, the present invention directly dehydrates and polycondenses lactic acid and/or glycolic acid with γ-butyrolactone, δ-valerolactone and/or ε-caprolactone, thereby producing lactic acid and/or glycolic acid (A), γ-butyrolactone, δ- The molar ratio with valerolactone and/or ε-caprolactone (B) is
That is, the (A)/(B) molar ratio is 20/80 to 90.
/10, and the number average molecular weight is 500 to
The present invention relates to a biodegradable copolymer composite in which a drug is mixed with a biodegradable copolymer having a molecular weight in the range of 5,000 and a drug, and a drug is given a sustained release function.

[Production use] The present invention will be explained in more detail below.

In the present invention, first, a biodegradable copolymer is obtained by direct dehydration polycondensation of lactic acid and/or glycolic acid and γ-butyrolactone, δ-valerolactone and/or ε-caprolactone.

There is no particular limitation on the type of lactic acid, and there are D-form, L-form, and D-form.
It may be any of the L-forms.

Regarding the proportions of these monomers used, the copolymer obtained after direct dehydration polycondensation has a molar ratio of lactic acid and/or glycolic acid (A) to γ-butyrolactone, δ-valerolactone and/or ε-caprolactone (B). ,
That is, the (A)/(B) molar ratio is 20/80 to 90/1
Use the ratio so that it is in the range of 0. In this case, if this molar ratio exceeds 90/10 and the amount of lactic acid and glycolic acid increases, the degree of crystallization will increase, and a mixture of this substance and the drug will form a non-uniform matrix. , the drug release rate becomes too high, making it undesirable as a base. On the other hand, the molar ratio is 20
/80, and when 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, and the sustained release properties of the base material are significantly reduced. This is not desirable as it decreases.

Lactic acid and/or glycolic acid and γ-butyrolactone, δ
- Direct dehydration polycondensation reaction with valerolactone and/or ε-caprolactone can be carried out by introducing nitrogen gas into the raw material liquid without a catalyst, or at a temperature of 150 to 250 °C under a reduced pressure of about 10 to 100 auaHg. The heating reaction may be carried out for up to 30 hours, but is not particularly limited to these conditions. In the present invention, although it is possible to carry out the reaction without a catalyst, there is no need for a catalyst removal operation, and the resulting copolymer is therefore preferable as a DDS base for biological use since it does not contain impurities such as organic solvents. .

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
- The number average molecular weight of the copolymer with valerolactone and/or ε-caprolactone is 500 to 5,000.

If the molecular weight of this copolymer deviates from this range and is less than 500, the release of the drug added and mixed in a later stage will be extremely rapid, and it will not function as a sustained release base at all. On the other hand, if the number average molecular weight exceeds 5.000, the resulting copolymer becomes rubbery and difficult to add and mix with a 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 may include hormones, antihistamines, antihypertensives, vasodilators, vascular reinforcing agents,
Digestive agents for the stomach, intestinal regulation agents, contraceptives, disinfectants for the skin, agents for parasitic skin diseases, anti-inflammatory agents, analgesics, choleretic agents, antirheumatic drugs, cardiotonic agents, hemorrhoid treatment agents, constipation treatment agents, vitamin preparations, Various enzyme preparations, vaccines, antiprotozoal agents, interferon inducers, anthelmintics, fish disease drugs, pesticides, plant hormones such as auxin, gibberellin, cytokinin, abscisic acid,
Drugs such as 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 shown. For example, lactic acid and/or glycolic acid and γ-butyrolactone, δ-valerolactone and/or - Direct dehydration polycondensation with caprolactone, lactic acid and/or glycolic acid (A) and γ-
The molar ratio of butyrolactone, δ-valerolactone and/or ε-caprolactone (B) is (A)/(
B) Appropriately select a biodegradable copolymer with a molar ratio in the range of 20/80 to 90/10 and a number average molecular weight in the range of 500 to 5.000, add a certain amount to a container, and usually Add a certain amount of the aforementioned drug to this,
Sufficient mixing is sufficient. Further, when the copolymer needs to be heated and melted, 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 composite obtained in this way, in which the drug of the present invention is given a sustained release function, has excellent sustained release properties,
Since it does not contain impurities, it has no side effects on living organisms, and since it is in a paste-like form, it is easy to mold, making it an excellent DDS composite for living organisms that can be applied to a wide range of applications.

Specific examples of its usage are as follows.

■ A method in which the complex is filled into a flexible container with a pointed tip and injected by incising a part of the living body during use (see Figure 8). ■ The complex is applied to the surface of a sheet-like material and used as a poultice. (See Figure 9) ■ A syringe-type disposable type method in which the compound is filled into a tubular container such as a Teflon tube, extruded, and can be inserted by injection (See Figure 10) When sterilizing these items, it is possible to sterilize them using a radiation source, and in this case, it is ideal to select a radiation source that can sterilize the inside of the composite. Therefore, the types include Co,
Using a γ-ray source and a β-ray source with strong penetrating power such as Cs,
Irradiation dose is 5×10 rad ~5 Xl06 rad
is appropriate.

[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 = 30/7
0 (molar ratio)) was placed in a 200 ml reaction vessel, and while introducing nitrogen gas into the mixture at a rate of 200 ml/ml, the mixture was heated at 200°C for 2 hours (Example 1) and 4 hours (Example 2). ), 8 hours (Example 3) and 16 hours (Example 4).

To 100 mg of these copolymers, 1 mg of calcitonin (an osteoporosis therapeutic drug) was added as a drug and 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. The in vivo decomposition rate was determined by first filling an ointment container (with Teflon coating inside) and injecting the complex into the lower part of the rat's back skin, which was incised. Next, rats were sacrificed in the mouth for one week after implantation of the composite, the amount of the remaining composite was measured, and the degradation rate was calculated from the amount injected.

These results are shown in Table 1.

For comparison, a mixture of monolactic acid and δ-valerolactone [L-lactic acid/δ-valerolactone-30/70
(Mole ratio)) was similarly placed in a 200 ml reaction vessel, and reacted at 200°C for 1 hour while introducing nitrogen gas into the mixture at a rate of 200 ml/ml to form a copolymer with a number average molecular weight of 300. I got it.

(Comparative Example 1) For further comparison, a high molecular weight copolymer of L-lactic acid and δ-valerolactone was obtained.

The method involves using a mixture of L-lactide (100%) and the above δ-valerolactone [L-lactic acid/δ-valerolactone = 30
/70 (mole ratio) conversion value] was placed in a 20 ml glass ampoule, and tin octoate was added as a catalyst at 0.1% relative to the total weight of L-lactide and δ-valerolactone.
%, the container was sealed, and freeze-degassing was repeated three times, and then 11 g of I
Allowed time to react. After dissolving the resulting copolymer in chloroform and subsequent precipitation in a large amount of methanol, 3
Vacuum drying was carried out at 0°C to obtain a rubbery copolymer at room temperature. (Comparative Example 2) Regarding the copolymers obtained in Comparative Examples 1 and 2, the physical properties and in vf of a composite obtained by adding and mixing calcitonin as a drug in the same manner as in Examples 1 to 4.
The vo decomposition rate was measured. The results are shown in Table 1.

Examples 5-8 L-lactic acid (90%) and δ-valerolactone (100%)
) at a mixing molar ratio (L-lactic acid/δ-valerolactone molar ratio) of 20/80 (Example 5) and 50150, respectively.
(Example 6), 70/30 (Example 7), 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.

In order to obtain a homopolymer of L-lactic acid for 50 g of L-lactic acid and δ-valerolactone at a mixing molar ratio (L-lactic acid/δ-valerolactone molar ratio) of 10/90 (Comparative Example 3), For 70 g of L-lactic acid (90%) (comparative example 4), 60 g of δ-valerolactone (100%) to obtain a homopolymer of δ-valerolactone
and 10 g of water (Comparative Example 5) were similarly placed in each 200 ml reaction vessel.

While introducing nitrogen gas at a rate of 200 ml/ff1in into these solutions prepared as Examples and Comparative Examples,
The reaction was carried out at 200° C. for 10 hours to obtain a copolymer and a homopolymer.

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 1n vivo degradation rate of these complexes were measured.

Incidentally, the in vivo decomposition rate was determined by the following method.

First, put a predetermined amount of the composite into a Teflon tube (inner diameter 2mmφ).
, length 50 mm) and molded at 70° C. under a pressure of 100 kg/cJ. Through this treatment, the composite filled in the Teflon tube became rod-shaped with an inner diameter of 2 mm. Next, in this state, the pointed end of the tube was inserted into the lower skin of the rat's back, and the composite was inserted in the injection state using a stainless steel rod-shaped extruder.

Two weeks after implantation of the composite, the rats were sacrificed by mouth, the amount of the remaining composite was measured, and one skewer was calculated from the injection amount.

These results are shown in Table 2.

Examples 9 to 11 90% D-lactic acid (Example 9) was used instead of L-lactic acid in Example 4.
), 90% DL-lactic acid (Example 10) and 100% glycolic acid (Example 11).

One portion 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 were reported in a third
Shown in the table. In addition, the in vivo degradation rate in rats was measured at regular intervals, and the changes in the degradation rate are shown in FIG.

Examples 12 to 13 Copolymers were similarly synthesized using 100% γ-butyrolactone (Example 12) and 100% ε-caprolactone (Example 13) in place of δ-valerolactone in Example 7.

The properties of the obtained copolymers were examined by X-ray diffraction, and all of them were found to be of poor quality.

1 mg of calcitonin as a drug was added to 100 mg of these copolymers and mixed until uniform. 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.

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 (lutein) as a drug.
lzing hormone releasing h
ormone, hereinafter abbreviated as LH-RH. The amino acid sequence of natural LH-RH is pGlu-Hls-Tr.
p-5er-Tyr-Gly-Leu-Arg-Pro
-Gly-NH2) (Example 14),
Similarly, it is a substance similar to LH-RH (Gly-OH”
)-L H-RH (Example 15), [D-A
la6] -LH-RH (Example 16), CD
-Phe2, D-Ala6)-LH-RH 5mg (
Example 17), (Ac-D-Pcl-Phe, D
-Trp3, D-1,2 Arg6, D-Ala”)-LH-RH (Example 18), (dcs-Gly”, D-Leu8)-L
5 mg of H-RH (Example 19) was placed in each glass test tube, and mixed and stirred at a temperature of 70° C. for 3 minutes.

The copolymer and drug melted quickly under these conditions, resulting in a homogeneous complex. After cooling the composite, it was placed in a disposable type Teflon tube (inner diameter 2mmφ, length 60m).
m) and molded for 2 minutes at a temperature of 50° C. under a pressure of 100 kg/crI. Through this treatment, the composite filled in the Teflon tube became rod-shaped with an inner diameter of 2 mmφ and a length of 15 mm.

In order to sterilize this molded composite, it was heated at -78°C (dry ice-methanol) in a nitrogen atmosphere for 60°C.
γ-rays from a Co source at a dose rate of IXl06R/h
Irradiated for hours.

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, weight 400-500 g).
The tip of a disposable Teflon tube was inserted into the lower back skin of the patient, and the entire amount of the filled composite was extruded using a Teflon rod.

After a predetermined period of time had elapsed, the rats were sacrificed, the complex was extracted, the amount of remaining drug was measured, and the drug release rate was calculated from the injected amount.

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 effects of drugs (physiologically active substances) were evaluated in rats.
Prostate compound weight per g body weight (mg/100gbw)
The results are shown in Figure 3.

Example 20 1 g of a copolymer (L-lactic acid/γ-butyrolactone molar ratio 78/22) synthesized in the same manner as in Example 12 and 100 mg of estramustin (anticancer drug) as a drug were completely added to 10 ml of methylene chloride. Dissolved. A methylene chloride solution containing this drug and copolymer was mixed with a 1% polyvinyl alcohol aqueous solution at 20%
0 ml using a dropper while stirring at 400 rpm, and after the dropwise addition was completed, the mixture was further stirred at room temperature for 24 hours. Through this operation, the complex of the present invention containing estramastine as a drug was made into fine particles (30 to 50 μm). 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 a rat's back using a syringe. The pharmacological action of the drug was determined by calculating the weight of the compound prostate per 100 g of rat body weight ffi (mg
/100gbv), and the results are shown in FIG.

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 loOmg of Cephalothin (antibiotic) as a drug (Example 21) Similarly, 1100 mg of gentamicin [Example 22), indacin [Ind.
acin, (antipyretic agent)] (Example 23)
), Indomethacin,
(Anti-inflammatory agent)] (Example 24), 1,100 mg of Phcnobarbitone (Carotonic agent) (Example 25), caffeine (Ca
ffcin.

(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.

The in vitro drug release test was performed using the Memplan diffusion method (
(see FIG. 5), and the results are shown in Table 5.

Table 5 Example 27 1 g of the copolymer synthesized in the same manner as in Example 13 and 0 of [toraful, (anticancer drug)]
．． 1 g was mixed. Using this complex of the present invention, In
viv.

The blood concentration of ftorafur was measured.

The method involved filling the above complex into an enema-like container, injecting the entire amount through the anus of a mongrel dog (weight 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 (anticancer drug) as a drug, the blood concentration of estracyte was measured in vivo.

The method involves adding 0.5 g of the above complex (Estracyte 50
(mg equivalent) was filled into an enema-like container, and the entire amount was injected through the anus of a rabbit (weight 4 kg), and the blood concentration of estracyte was measured at predetermined intervals.

The results are shown in Figure 7.

Examples 29 to 31 0.5 g of a (DL-lactic acid/δ-valerolactone molar ratio 30/70) copolymer (number average molecular ffi 2200) synthesized in the same manner as in Example 10 and 100 mg of calcitonin as a drug (Example 29 ), 100 μg of testosterone [Tc5tostcronc, (hormone agent)] (Example 30), and 1 μg of natural LH-RH.
00 mg (Example 31) were mixed while heating at a temperature of 80°C. These complexes are applied to textile materials,
This was applied to the back epidermis of a hairless mouse (weight 100 g).

The mice were sacrificed at predetermined intervals, and the drug concentration in the blood of the mice was measured.

The results are shown in Table 6.

Chapter 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. FIG. 2 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 Examples 14 to 19 and the in-vivo implantation period. FIG. 3 is a graph showing the relationship between the pharmacological action of hormones released from the composites of the present invention produced in Examples 14 to 19 (represented by polymerization of prostatic compound) and the period of in vivo implantation. FIG. 4 is a graph showing the relationship between the pharmacological action of the hormone released from the composite of the present invention produced in Example 20 (expressed by the weight of the compound prostate gland) and the period of in vivo implantation. FIG. 5 is a schematic diagram of an in vitro release test apparatus using the Menplan diffusion method used in Examples 21 to 26. Figures 6 and 7 show the relationship between the pharmacological action of the hormones released from the composites of the present invention produced in Examples 27 and 28 (represented by the polymerization of the prostatic compound) and the period of in-vivo implantation. It is a graph. 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 (1000ml) 5... complex
6... Suitable material 7... Teflon-treated flexible container with a pointed tip 8... Syringe-shaped disposer

Claims (1)

[Claims] Lactic acid and/or glycolic acid and γ-butyrolactone, δ
- direct dehydration polycondensation of valerolactone and/or ε-caprolactone, lactic acid and/or glycolic acid (A) and γ-butyrolactone, δ-valerolactone and/or ε-caprolactone;
- the molar ratio with caprolactone (B) is (A)/
(B) A drug prepared by mixing a biodegradable copolymer with a molar ratio in the range of 20/80 to 90/10 and a number average molecular weight in the range of 500 to 5,000, and a drug with sustained release properties. A functionalized biodegradable copolymer complex.