JP2002138036A - System for controlling drug release - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for controlling drug release which realizes appropriate control of rate and duration of drug release and which can be used, without limitations to types of drugs, in retina or vitreous. SOLUTION: This system for controlling drug release is composed of a nanosphere which comprises nano-size particles. The particles are made of a synthetic biodegradable polymer and contain drugs uniformly. Using the system, efficient delivery of drugs to retina or vitreous, as target sites is realized. The synthetic biodegradable polymer is preferably a polylactic acid or a lactic acid-glycolic acid copolymer. The drugs are contained in the particles preferably as a matrix. The average particle diameter of the nanosphere is preferably from 50 to 200 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a system for controlling drug release into the retina or vitreous body.

[0002]

2. Description of the Related Art There are many intractable diseases in the inner eye such as the retina and the vitreous body, and it is desired to develop an effective treatment. For eye diseases, it is most common to treat the drug by eye drops, but the drug hardly transfers to the inner eye such as the retina and the vitreous body. This makes treatment of diseases in the inner eye more difficult. Since the intraocular transfer of a systemically administered drug is limited by the blood-eye barrier, it is difficult to transfer the drug to an effective concentration.

[0003] Therefore, a method of directly administering a drug to the inner ocular region has been attempted. For example, a technique of administering a liposome or microsphere containing a drug to the inner ocular region such as the vitreous body has been reported. However, liposomes have difficulty in controlling drug release, and microspheres have a large particle size, so there is a problem in maintaining uniform dispersibility and transparency in the vitreous body, and nanospheres and nanocapsules with smaller particle sizes are problematic. Studies have been conducted to incorporate the drug into the vitreous body. For example, a drug carrier system containing spherical particles having a diameter of 1 μm or less (Tokuhei 6-50836)
9) and administration of an ophthalmic preparation containing nanocapsules to the vitreous body (Japanese Patent Application Laid-Open No. 4-221322). However, Japanese Patent Application Laid-Open No. 6-508369 discloses a method in which a bioadhesive polymer is used as a carrier and a drug is adsorbed to the polymer, and the effect of appropriately controlling the release rate and duration of the drug is not satisfactory. No. 4,221,322 relates to a nanocapsule containing a central core having lipid properties, which is applicable only to fat-soluble drugs, and also satisfies an appropriate control effect on the release rate and duration of the drug. Not something you can do.

[0004]

Therefore, there is a need to develop a drug release control system that can control the release rate and duration of a drug appropriately and that can be applied to the retina or vitreous body without restriction on the type of drug. Was desired.

[0005]

Means for Solving the Problems The present inventors have paid attention to the use of nanospheres as this drug release control system.

Accordingly, as a result of research on nanosphere materials, the use of synthetic biodegradable polymers results in the carrier being rapidly decomposed and absorbed together with the release of the drug or after the release of the drug, making it suitable for actual medical treatment. It has been found that nanospheres can be obtained. In addition, by using this synthetic biodegradable polymer, the drug can be contained as a matrix type, enabling uniform dispersion of the drug within the fine particles, and further, the release rate and sustained release of the drug based on the decomposition of the carrier. We have found that time can be controlled appropriately.

Next, as a result of studying the particle size of the fine particles forming the nanospheres, it was found that uniform dispersibility of the fine particles in the retina or the vitreous body can be ensured by using nano-sized fine particles. Furthermore, the nanospheres administered into the vitreous are taken up into the retina in a state in which the nanospheres contain a drug, and the smaller the particle size, the longer the nanospheres remain in the retina or the vitreous, especially when the particle size is 200 nm. When the following nanospheres were selected, they were found to remain in the retina for a long period of time, thereby more suitably improving the sustainability of the drug concentration in the retina.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a drug which comprises administering to a retina or vitreous a nanosphere in which a drug is uniformly contained in fine particles formed of a nano-sized synthetic biodegradable polymer. The present invention relates to a controlled release system, 1) ensuring uniform dispersibility of the fine particles in the vitreous body by using nano-sized fine particles, and 2) forming the fine particles with a synthetic biodegradable polymer,
It is designed so that the carrier is decomposed and absorbed with the release of the drug or immediately after the release of the drug. 3) The drug is contained in the fine particles as a matrix type, thereby enabling the uniform dispersion of the drug in the fine particles. In addition, the drug release rate and duration in the retina or vitreous body can be appropriately controlled.

Further, the drug release control system of the present invention comprises:
Consisting of nanospheres containing a drug uniformly in microparticles formed of nanosized synthetic biodegradable polymer,
By administering the drug to the retina or the vitreous as the target site, the drug can be efficiently delivered to the retina or the vitreous.

In the present invention, the type of the synthetic biodegradable polymer forming the nanosphere is not particularly limited, but specific examples include polylactic acid, lactic acid-glycolic acid copolymer, and polyanhydride (Polyanhydride).
ydride), polyorthoester (Poly (or
the ester)), polyepsilon caprolactone (Poly ε-caprolactone), polyalkylcyanoacrylate (Polyalkylc)
yanoacrylate), polyhydroxyalkanoate (Polyhydroxyalkanoate)
e), polyphosphoester (Polyphosphh)
oster) and the like. Preferred examples are polylactic acid or lactic acid-glycolic acid copolymer. The lactic acid unit component includes L-form and D-form.
A body or a DL body can be used.

[0011] The molecular weight of these synthetic biodegradable polymers is not particularly limited, and can be appropriately selected depending on the kind of the drug contained in the nanosphere, the necessary effective concentration of the drug, the release period of the drug, and the like.

In the present invention, the nanoparticle forming the nanosphere has a nanoparticle size, but when it is required to remain in the retina for a long time, it is more preferable to set the average particle size to 200 nm or less. preferable. The lower limit is not particularly limited, but if it is too small, it is preferably set to 50 nm or more due to manufacturing restrictions. The average particle diameter in the present invention was measured by a light scattering method.

The drug release control system of the present invention is used for treating or preventing various diseases of the retina and the vitreous body. Specific diseases include intraocular inflammation due to various causes, viral and bacterial infections, proliferative vitreoretinopathy with neovascular and retinal cell proliferation changes, retinal hemorrhage due to various causes, retinal detachment, Retinoblasts and the like.
There is no particular limitation on the drug contained in the nanosphere, and a drug suitable for the target disease can be selected.
For example, in the case of inflammation due to internal eye surgery, an anti-inflammatory agent such as betamethasone may be used in the case of autoimmune uveitis,
Immunosuppressants such as cyclosporine, antivirals such as ganciclovir for viral infections, antibacterials such as ofloxacin for postoperative infections, and doxorubicin for proliferative vitreoretinopathy , Carmustine and the like are used. Of course, these drugs may be in the form of salts such as hydrochloride or esters such as phosphate.

The amount of the drug contained in the nanosphere may be appropriately increased or decreased according to the kind of the drug, the required effective concentration of the drug, the release period of the drug, the symptoms, and the like. Typically, the drug will be from 0.01 to 10% by weight of the nanospheres, preferably from 0.1 to 10%.
The content of the drug is 1 to 5% by weight, and the content of the drug can be determined in consideration of the balance between the sustained release effect and the amount required for treatment.

The nanosphere used in the present invention can be produced by using a known interface deposition method or interface reaction method.
More specifically, an in-liquid drying method which is an interfacial deposition method (J. Control. Release, 2, 343-
352 (1985); Controlled. Re
lease, 36, 1095-1103 (1988))
And the like by an interfacial polymerization method (Int. J. Ph.
erm. , 28, 125-132 (1986)), a self-emulsifying solvent diffusion method (J. Control. Releases).
e, 25, 89-98 (1993)), etc., and from these production methods, considering the particle size of the nanospheres, the type, properties and content of the drug contained, and the like, an appropriate production The method may be appropriately selected.

As a specific example of the production of nanospheres,
Examples of the production of nanospheres containing betamethasone, which is an anti-inflammatory agent, as a drug and using a lactic acid-glycolic acid copolymer as a carrier are shown in Examples below.

The effect of the present invention will be described in detail in the section of the intravitreal drug concentration measurement test described below. By using betamethasone as an example of a drug, the time-dependent change in the drug concentration in the vitreous body is measured, and its half is reduced. When the synthetic biodegradable polymer is used as a carrier, the drug can be released almost linearly over time even if the particle size is slightly large. Was found to be longer and sustained drug concentration in the vitreous was achieved.

Further, since the synthetic biodegradable polymer is used in the present invention, the carrier is decomposed and absorbed at the same time as the release of the drug or immediately after the release of the drug, and the decomposition rate is determined by the molecular weight of the synthetic biodegradable polymer. Since it can be controlled, the release rate of the drug can be controlled according to the purpose.

Further, in the present invention, as shown in the embodiments,
Since the nanospheres are produced by dissolving the carrier and the synthetic biodegradable polymer and the drug in an appropriate solvent, the drug can be contained in the microparticles in a matrix form,
Uniform dispersibility of the drug in the fine particles can be ensured.

The selection of an appropriate particle size was examined by using polystyrene nanospheres containing a fluorescent dye to test the persistence in the inner eye portion at various particle sizes. In addition, when the histological evaluation was performed,
It has been found that as the particle size of the nanospheres becomes smaller, the nanospheres present in the inner eye for a longer period and having a particle size of 200 nm or less are more suitably taken into the retina. The results of this test show that controlling the particle size of nanospheres can not only control the persistence of drug efficacy in the retina or vitreous, but also allow the nanospheres to be incorporated into the retina with the drug contained. It also shows that drug release can be controlled over a long period of time in the retina.

Furthermore, when the system of the present invention is used, the drug can be efficiently delivered to the retina or the vitreous, which is the target site, so that the compounding amount of the drug can be reduced and the effect of reducing side effects can be expected.

The nanosphere used in the drug release control system of the present invention is administered by various methods such as injection and infusion which can be introduced into the vitreous body. This preparation can be prepared using widely used preparation preparation techniques. For example, for injection, a drug-containing nanosphere is converted to BSS (Balanced Salt).
(Solution) solution. Specific preparation examples will be described in Examples.

These examples are provided to aid the understanding of the present invention and do not limit the scope of the invention.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Method for producing drug-containing nanospheres: Specific examples of the production of nanospheres that can be used in the drug release control system of the present invention are shown below. This method is based on a self-emulsifying solvent diffusion method (J. Control. Releases).
e, 25, 89-98 (1993)).

Production Example: Production of betamethasone-containing lactic acid-glycolic acid copolymer nanospheres betamethasone (10 mg) and weight average molecular weight 700
A lactic acid-glycolic acid copolymer (100 mg) having a copolymerization ratio of 50/50 is dissolved in dichloromethane (0.5 mL). Acetone (10 mL) is added to this and mixed well. This solution was added to an aqueous polyvinyl alcohol solution (2 w / v
%, 50 mL) with stirring. The mixture is stirred for 2 hours under reduced pressure, and filtered using a membrane filter (pore size: 1 μm). The filtrate was ultracentrifuged for 1 hour (15600
0 × g) to precipitate the nanospheres. An appropriate amount of purified water is added to the obtained nanospheres, redispersed, and ultracentrifuged again to wash the nanospheres. This washing operation is repeated twice. The precipitate finally obtained is redispersed in purified water (10 mL) and freeze-dried to obtain betamethasone-containing lactic acid-glycolic acid copolymer nanospheres (103 mg). The average particle size of the obtained nanospheres was 100 nm (measured by a light scattering method).

By increasing or decreasing the amount of acetone used, particles having various particle diameters such as 50 nm, 200 nm, and 500 nm can be obtained.

Hereinafter, unless otherwise specified, the nanospheres obtained in the above production examples are abbreviated as betamethasone-containing nanospheres.

In the same manner as above, cyclosporine,
Nanospheres using drugs such as ganciclovir, doxorubicin hydrochloride, and carmustine can be produced.

2. Formulation Preparation Example The following shows a preparation example of an injection solution.

The nanosphere powder containing betamethasone (5
0 mg) was redispersed in BSS (1 mL) to give an injection solution.

3. Intravitreal drug concentration measurement test Betamethasone-containing nanospheres (particle diameter 100 nm) produced in the above production example and particle diameter 1 μm as a comparative example
and betamethasone-containing nanospheres having a particle diameter of 10 μm (when the particle diameter is 1 μm or more, they are usually referred to as microspheres, but here, they are referred to as nanospheres for convenience; hereinafter the same unless otherwise specified), and the following method is used. Body concentrations were measured.

1) Ketamine hydrochloride aqueous solution (50 mg / m
L) and aqueous solution of xylazine hydrochloride (50 mg / mL) 7:
The three mixed solutions were intramuscularly administered to colored rabbits and anesthetized.

2) Tropicamide (0.5%) / phenylephrine hydrochloride (0.5%) ophthalmic solution was applied to both eyes to cause mydriasis.

3) Oxybuprocaine hydrochloride (0.
5%) The eye was anesthetized with eye drops.

4) Betamethasone-containing nanospheres were injected from the flat part of the eye ciliary body into the central part of the vitreous body of a colored rabbit under a surgical microscope using a syringe with a 27 G needle so that the amount of betamethasone per eye was 50 μg. did.

5) After sacrifice over time (3 days, 1 week, 2 weeks, 4 weeks) and enucleation, the vitreous body is collected.
The betamethasone concentration in the vitreous was measured by high performance liquid chromatography, and the half-life of the betamethasone concentration was calculated.

The betamethasone-containing nanospheres having a particle diameter of 1 μm and 10 μm were prepared according to the following method.

Betamethasone (10 mg) and a lactic acid-glycolic acid copolymer (100 mg) having a weight average molecular weight of 70000 and a copolymerization ratio of 50/50 were added to dichloromethane (0.1 mg).
5 mL). Acetone (7.5 mL) is added to this and mixed well. This solution is added dropwise to a polyvinyl alcohol aqueous solution (2 w / v%, 50 mL) with stirring. The mixture is stirred for 2 hours under reduced pressure, and the liquid is filtered using a membrane filter (pore size: 1 μm). An appropriate amount of purified water is added to the collected material, which is re-dispersed and washed by centrifugation. This washing operation is repeated twice. The finally obtained precipitate is redispersed in purified water (10 mL) and freeze-dried to obtain betamethasone-containing microspheres having an average particle diameter of 1 μm.

In the above method, the amount of acetone was changed to 6 mL, and the pore diameter of the filter was changed to obtain an average particle diameter of 1 mL.
0 μm betamethasone-containing microspheres are obtained.

(Results and Discussion) All the results were shown as average values of four eyes. The half-life of betamethasone concentration is 10
848 hours with 0 nm nanospheres, 1
In the case of μm, it was 565 hours, and in the case of 10 μm, it was 113 hours.

FIG. 1 shows the results of the time course of the concentration of the drug.

As shown in FIG. 1, almost linear release of the drug was observed in each nanosphere with the passage of time. It has been found that a sustained release over a period of time is also possible. In addition, from FIG. 1 and the result of the half-life calculation, it has been clarified that the drug concentration can be maintained at a high level for a long period of time when the particle size is made nano-sized.

4. Intraocular persistence test Commercially available nanospheres (Polysc) containing polystyrene as a carrier and containing a fluorescent dye (fluorescein)
products, Inc., trade name Fluoresbri
te), the following experiment was performed.

Preparation of nanosphere suspension: 2.5% fluorescent dye (maximum excitation wavelength: 458 nm, maximum fluorescence wavelength: 5
40 nm) containing polystyrene nanospheres (particle size 5)
0 nm) The suspension was diluted 200-fold with sterile purified water, and a sodium fluorescein aqueous solution (10.0 μg / mL) was used.
And the same fluorescence intensity.

The nanosphere has a particle diameter of 50 n.
Suspensions of m, 100 nm, 200 nm, 2 μm and 20 μm were similarly prepared. An aqueous solution of sodium fluorescein (10.0 μg / mL) was used as a control solution.

Administration and Measurement Methods: 1) A 7: 3 mixed solution of an aqueous ketamine hydrochloride solution (50 mg / mL) and an aqueous xylazine hydrochloride solution (50 mg / mL) was intramuscularly administered to a colored rabbit and anesthetized.

2) Tropicamide (0.5%) / phenylephrine hydrochloride (0.5%) ophthalmic solution was applied to both eyes to cause mydriasis.

3) Oxybuprocaine hydrochloride (0.
5%) The eye was anesthetized with eye drops.

4) Using a syringe with a 30G needle from the flat part of the eye ciliary body, a nanosphere suspension (0.1 mL) having a particle diameter of 50 nm was applied to one eye, and a control solution was applied to the other eye at the center of the vitreous body. Was administered.

5) Intravitreal administration 1, 3, 7, 14, 2
After 1, 28 days, using a vitreous fluorometry device,
The fluorescence intensity within the vitreous was measured over time, and the half-life was calculated.

Before measuring the fluorescence intensity in the vitreous,
Operations 1) and 2) were performed.

The particle diameters are 100 nm, 200 nm,
μm and 20 μm nanosphere suspensions,
The same operations as in 1) to 5) were performed.

Histological evaluation: 1) Two months after the administration of the nanospheres, Nembutal injection (5 mL) was intravenously administered into the ear vein to kill anesthesia.

2) Retinal frozen sections were prepared.

3) The sections were observed / photographed with a fluorescence microscope.

(Results and Discussion) Table 1 shows the half-life of the nanospheres of each particle diameter in the vitreous body. Also,
FIG. 2 shows a fluorescence micrograph showing that 200 nm nanospheres were incorporated into the retina.

[0057]

[Table 1]

Table 1 shows that the smaller the nanosphere particle size, the longer the drug remains in the eye for a longer period of time.
In addition, it was confirmed from FIG. 1 that nanospheres having a particle diameter of 200 nm were taken into the retina. In the case of nanospheres having a particle size larger than the nanosize, almost no uptake was observed.

That is, by controlling the particle size of the nanospheres, the persistence of the drug effect on the retina or vitreous can be remarkably improved. In particular, by setting the nanosphere particle diameter to 200 nm or less, by incorporating the nanospheres into the retina, it can be expected that drug release can be controlled from the retina for a long period of time.

[0060]

Thus, according to the present invention, it is possible to provide a therapeutic method in which the efficacy of the retina or vitreous body is improved.

[Brief description of the drawings]

FIG. 1 is a graph showing a time-dependent change in the concentration of betamethasone-containing nanospheres in a vitreous body.

FIG. 2 is a fluorescence micrograph showing that 200 nm nanospheres are incorporated into the retina.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) A61P 31/10 A61P 31/10 31/12 31/12 37/06 37/06 F term (reference) 4C076 AA65 BB24 CC04 CC07 CC31 CC35 EE24 EE48 FF31 FF32 FF33 FF34 FF68

Claims (6)

[Claims] 1. A drug release control system characterized in that a nanosphere in which a drug is uniformly contained in microparticles formed of a nanosized synthetic biodegradable polymer is administered to the retina or the vitreous body. 2. The drug release control system according to claim 1, wherein the synthetic biodegradable polymer is polylactic acid or lactic acid-glycolic acid copolymer. 3. The drug release control system according to claim 1, wherein the drug is contained in the fine particles as a matrix. 4. The nanosphere has an average particle size of 50 to 20.
2. The drug release control system according to claim 1, which is 0 nm. 5. The drug release control system according to claim 1, wherein the drug contained in the nanosphere is a drug for treating or preventing a retinal or vitreous disease. 6. The drug release control system according to claim 5, wherein the drug is an anti-inflammatory agent, an immunosuppressant, an antiviral, an antibacterial or an antifungal.