JP2000247871A - Control system for medicament release to retina or vitreous body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject control system intended to improve the medicinal efficacy sustainability in the retina or vitreous body by administration of nanospheres. SOLUTION: This control system is such one as to be intended to administer the retina or vitreous body with medicament-formulated nanospheres each <=200 nm, pref. 50-200 nm in diameter; wherein each of the nanospheres consists of a biodegradable polymer such as polylactic acid or lactic acid copolymer; and the medicament is intended for treating or preventing retina or vitreous body diseases, for example being an anti-inflammatory agent, immunosuppressant, antiviral agent, antibacterial agent, antimycotic agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for controlling the release of a drug into the retina or the vitreous body, and aims at improving the sustainability of the drug in the retina or the vitreous body by controlling the drug release. is there.

[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 the release of drugs, and liposomes and microspheres have a large particle size, so there is a problem in maintaining transparency in the vitreous body.Drugs can be added to nanospheres and nanocapsules with smaller particle sizes. Studies have been made to include and administer the vitreous. 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).

[0004]

However, there is no report on what kind of particle size of nanospheres can be used to effectively control the release of a drug, and there is no report on the transfer of nanospheres to the retina. No research reports.

[0005] Nanospheres are very useful as a means for controlling the release of a drug into the internal eye, but in order to apply it to actual medical treatment, it was necessary to find an appropriate particle size.

[0006]

Accordingly, the present inventors have focused on the particle size of nanospheres and conducted intensive research on a drug release control system to the retina or vitreous body.
Nanospheres administered intravitreally, the smaller their particle size, the longer they remain in the retina or vitreous,
It has been found that nanospheres having a particle diameter of 200 nm or less are taken up into the retina in a state containing a drug and remain in the retina for a long period of time, thereby enabling control of drug release in the retina.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for controlling the release of a drug into the retina or the vitreous body, which comprises administering a nanosphere containing a drug and having a particle diameter of 200 nm or less. Is to improve the persistence of drug efficacy in the retina or vitreous by administering nanospheres having a small particle size, in particular,
It is to improve the persistence of the drug effect in the retina.

[0008] The drug release control system in the present invention is a system that efficiently delivers a drug to a target site (retina or vitreous body) so that the drug effect can be continuously exhibited.

The particle size of the nanospheres in the present invention may be 200 nm or less, and the lower limit thereof is not particularly limited. However, if the particle size is too small, a particle size in the range of 50 to 200 nm is preferable due to production restrictions. .

The material for forming the nanosphere in the present invention is not particularly limited as long as it is a biodegradable polymer, and specific examples thereof include polylactic acid, lactic acid copolymer, polyamino acid, hyaluronic acid, and collagen. And biodegradable polymers such as gelatin and albumin. Preferred examples are polylactic acid or lactic acid-glycolic acid copolymer. As the lactic acid unit component, L-form, D-form or DL-form can be used.

The molecular weight of these biodegradable polymers is not particularly limited, but can be appropriately selected depending on the type of drug contained in the nanosphere, the required effective concentration of the drug, the release period of the drug, and the like.

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,
Drugs suitable for the target disease can be selected. For example, in the case of inflammation associated with internal eye surgery, an anti-inflammatory agent such as betamethasone phosphate is used, and in the case of autoimmune uveitis, an immunosuppressant such as cyclosporin is used in the case of viral infection. Are antiviral agents such as ganciclovir, antibacterial agents such as ofloxacin for postoperative infections, doxorubicin hydrochloride and carmustine for proliferative vitreoretinopathy. The amount of the drug contained in the nanosphere may be appropriately increased or decreased according to the type of the drug, the required effective concentration of the drug, the release period of the drug, the symptoms, and the like. Usually, the drug is 0.01 to 10% by weight, preferably 0.1 to 5% by weight of the nanosphere, but the content of the drug is determined in consideration of the balance between the sustained release effect and the amount required for treatment. You can decide.

The nanosphere of the present invention can be manufactured by using a known interface deposition method or interface reaction method. More specifically, a submerged drying method (JC) which is an interfacial deposition method.
ontrol. Release, 2 , 343-352
(1985); Controlled. Relea
Se, 36 , 1095-1103 (1988)) and the like, an interfacial polymerization method (Int. J. Pher) which is an interfacial reaction method.
m. , 28 , 125-132 (1986)), a self-emulsifying solvent diffusion method (J. Control. Release,
25 , 89-98 (1993)) and the like, and appropriate methods can be used in consideration of the particle size of the nanospheres, the type, properties, and the content of the drug contained in the nanospheres. What is necessary is just to select a manufacturing method suitably.

As specific examples of the production of the nanospheres of the present invention, examples of the production of nanospheres containing carmustine which is a therapeutic agent for proliferative vitreoretinopathy as a drug and using polylactic acid as a material for the nanospheres, Examples of the production of nanospheres containing betamethasone phosphate as an anti-inflammatory agent and using a lactic acid-glycolic acid copolymer as a material for the nanospheres are shown in Examples below.

The effect of the present invention will be described in detail in an intraocular persistence test described below. However, it is difficult to trace a small amount of tissue transfer using a drug-containing nanosphere in terms of measurement technology. Using a nanosphere containing a fluorescent dye instead of a drug, the persistence in the inner ocular region at various particle sizes was examined. In addition, histological evaluation revealed that nanospheres were present in the inner eye for a longer period as the particle size became smaller, and that nanospheres having a particle size of 200 nm or less were taken into the retina.

The results of this test show that controlling the particle size of the nanosphere not only significantly improves the persistence of the drug effect on the retina or vitreous body, but also reduces the particle size of the nanosphere to 200 nm or less. It shows that nanospheres can be taken into the retina in a state containing a drug, and that drug release can be controlled for a long time in the retina.

Furthermore, by efficiently delivering a drug to a target site (retina), the compounding amount of the drug can be reduced, and an effect of reducing side effects can be expected.

The nanospheres in the drug release control system of the present invention are administered by various methods such as injection and infusion which can be introduced into the vitreous body. In addition, a formulation suitable for the administration method can be prepared by a commonly used formulation for intravitreal administration. For example, in the case of an injection, a specific preparation example will be described in the Examples section.
(Solution) solution.

Next, some examples of the present invention will be described. However, these examples are for the purpose of assisting the understanding of the present invention, and do not limit the scope of the invention.

[0020]

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 1 (Carmustine-containing polylactic acid nanosphere) Carmustine (10 mg) and polylactic acid (100 mg) having a weight average molecular weight of 85,000 were mixed with dichloromethane (0.5 m 2).
Dissolve in 1). Acetone (40 ml) is added to this and mixed well. This solution is added dropwise to a stirring aqueous polyvinyl alcohol solution (2% w / v, 50 ml). This mixture is stirred under reduced pressure for 2 hours, and filtered using a membrane filter (pore size: 1 μm). The filtrate is ultracentrifuged (156,000 × g) for 1 hour 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 re-dispersed in purified water (10 ml) and freeze-dried to obtain carmustine-containing polylactic acid nanospheres (108 mg). The average particle size of the obtained nanospheres is 100 nm (measured by a light scattering method).

Production Example 2 (Lactate-glycolic acid copolymer nanosphere containing betamethasone phosphate) Betamethasone phosphate (10 mg) and a lactic acid-licholate copolymer having a weight average molecular weight of 65,000 and a copolymerization ratio of 50/50 ( 100 mg) in dichloromethane (0.5 ml). Add acetone (25
ml) and mix well. Methanol (5m
1) is added to completely dissolve the betamethasone phosphate. The aqueous solution of polyvinyl alcohol (2
(w / v%, 50 ml). This mixture was stirred under reduced pressure for 2 hours, and a membrane filter (pore size: 1 μm)
Use and filter. The filtrate is ultracentrifuged for 1 hour (15
6,000 × 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 finally obtained precipitate is redispersed in purified water (10 ml) and freeze-dried to obtain a lactic acid-glycolic acid copolymer nanosphere containing betamethasone phosphate (103 mg). The average particle size of the obtained nanospheres is 200 nm (measured by a light scattering method).

Hereinafter, unless otherwise specified, Production Example 1 is abbreviated as carmustine-containing nanospheres, and Production Example 2 is abbreviated as betamethasone phosphate-containing nanospheres.

2. Formulation Examples Hereinafter, preparation examples of injection solutions will be described. Carmustine-containing nanosphere powder (50 mg) was redispersed in BSS (1 ml) to give an injection. In addition, nanospheres containing betamethasone phosphate can be similarly prepared.

3. Intraocular persistence test Using the drug-containing nanospheres actually produced above,
Tracking trace tissue migration is difficult with measurement techniques. Therefore, in this test, polystyrene nanospheres containing a commercially available fluorescent dye (Polysciences,
The following experiment was performed using Fluoresbrite (trade name, manufactured by Inc.).

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 an aqueous solution of sodium fluorescein (10.0 μg / ml) was used.
And the same fluorescence intensity. In addition, a particle diameter of 50 nm,
Suspensions of 0 nm, 200 nm, 2 μm and 20 μm nanospheres were similarly prepared. An aqueous solution of sodium fluorescein (10.0 μg / ml) was used as a control solution.

Administration method and measurement method: 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. Both eyes were instilled with tropicamide (0.5%) / phenylephrine hydrochloride (0.5%) eye drops to cause mydriasis.

3. Oxybuprocaine hydrochloride (0.
5%) An ophthalmic solution was instilled to anesthetize the eye surface.

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

5. Intravitreal administration 1, 3, 7, 14, 21
And 28 days later, the intravitreal fluorescence intensity was measured over time using a vitreous fluorometer to calculate the half-life.

Before measuring the fluorescence intensity in the vitreous, And 2. Was performed. In addition, particle diameter 100n
m, 200 nm, 2 μm and 20 μm using nanosphere suspensions To 5. The same operation was performed.

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

2. Retinal frozen sections were prepared.

3. The sections were observed and 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, 2
FIG. 1 shows a fluorescence micrograph showing that 00 nm nanospheres are incorporated into the retina.

[0037]

[Table 1]

As can be seen from Table 1, the smaller the nanosphere particle size, the longer the nanospheres remain in the eye for a long time. Also,
From the micrograph of FIG. 1, it was confirmed that nanospheres having a particle diameter of 200 nm were taken into the retina. still,
Incorporation was hardly observed in the nanosphere having a large particle diameter. In other words, by controlling the particle size of the nanospheres, the persistence of the drug effect in the retina or vitreous is remarkably improved. In particular, by making the nanosphere particle size 200 nm or less, the nanospheres are taken into the retina. It can be expected that drug release can be controlled from inside the retina for a long period of time.

[0039]

According to the present invention, it is possible to provide a treatment method in which the persistence of the drug effect in the retina or vitreous body is improved.

[Brief description of the drawings]

FIG. 1 is a fluorescence micrograph showing that nanospheres having a particle diameter of 200 nm are incorporated into the retina.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshinori Ozeki 207 Verdur Yagoto 207 7-2 Midorigaoka, Yatomi-cho, Mizuho-ku, Nagoya-shi, Aichi Japan F-term in Nara RD Center Co., Ltd. (reference) 4C076 AA67 AA95 BB24 CC04 CC07 CC10 CC32 CC34 CC35 DD43 EE24 EE48 FF32 FF68

Claims (6)

[Claims] 1. A system for controlling drug release to the retina or vitreous, which comprises administering nanospheres having a particle diameter of 200 nm or less containing a drug. 2. The nanosphere has a particle diameter of 50 to 200 n.
2. The drug release control system according to claim 1, wherein m is m. 3. The drug release control system according to claim 1, wherein the nanosphere is formed of a biodegradable polymer. 4. The drug release control system according to claim 1, wherein the biodegradable polymer is polylactic acid or a lactic acid copolymer. 5. The drug release control system according to claim 1, wherein the drug is a drug for treating or preventing a retinal or vitreous disease. 6. The drug release control system according to claim 1, wherein the drug is an anti-inflammatory agent, an immunosuppressant, an antiviral, an antibacterial or an antifungal.