JP7728656B2 - Liquid preparations containing brimonidine - Google Patents

Description

The present invention relates to a liquid formulation containing brimonidine or a salt thereof.

Brimonidine and its salts are known as alpha-2 adrenergic receptor agonists. The human eye contains many alpha-2 adrenergic receptors (hereinafter sometimes abbreviated as alpha-2 receptors). Alpha-2 receptor agonists reduce intraocular pressure by inhibiting aqueous humor production and promoting aqueous humor outflow via the uveoscleral outflow pathway. Based on this effect, alpha-2 receptor agonists have traditionally been used to treat glaucoma and ocular hypertension. Alpha-2 receptor agonists also cause a reduction in the lumen size of alpha-2 receptor-rich arterioles, particularly terminal arterioles. This action results in vasoconstriction, reducing redness and increasing whiteness of the eye, improving the aesthetic appearance of the eye (Patent Document 1: Japanese Patent No. 5671459; Patent Document 2: Japanese Patent No. 5738890).

Formulation technologies focusing on formulation stability for formulations containing brimonidine and/or its salts in combination with timolol and/or its salts have also been investigated. For example, Patent Document 3 (JP 2009-533462 A) discloses that a composition containing approximately 1 to 4.5 mM brimonidine and approximately 2 to 16 mM timolol and having a pH of approximately 7 to 8.5 can suppress the production of degradation products and has improved stability. Furthermore, Patent Document 4 (JP 2017-222707 A) discloses that by containing eye drops containing brimonidine and/or its salts and brinzolamide and/or its salts in a transparent container with a maximum transmittance of 67% or less for light with wavelengths of 360 to 460 nm and 78% or less for light with wavelengths of 600 to 680 nm, decomposition of brimonidine and/or its salts due to light exposure can be suppressed, thereby ensuring formulation stability.

When formulated as eye drops, well-known additives are added along with one or more active ingredients. When formulating a drug, active ingredients and additives cannot be combined arbitrarily; it is necessary to evaluate the stability, efficacy, safety, etc. of the formulation as a whole, taking into account the compatibility between the active ingredients and between the active ingredients and additives.

Patent No. 5671459 Patent No. 5738890 Special Publication No. 2009-533462 Japanese Patent Application Laid-Open No. 2017-222707

When formulating brimonidine or its salts into a liquid ophthalmic preparation that relieves or suppresses eye redness, it is necessary to consider the compatibility of the active ingredients to be combined and to select additives that are compatible with the active ingredients.

The inventors conducted extensive research with the aim of providing a stabilized ophthalmic liquid formulation containing low concentrations of brimonidine, and discovered that liquid formulations containing low concentrations of brimonidine are compatible with vitamins, and that the stability of vitamins, which are prone to loss of content, against light and heat is improved. They also discovered that ophthalmic liquid formulations containing low concentrations of brimonidine to which vitamins have been added have high conjunctival penetration.

As one embodiment of the present invention, there is provided the following liquid ophthalmic formulation.
[1] An ophthalmic liquid preparation containing 0.01 to 0.05 w/v % brimonidine and/or a salt thereof and vitamins.
[2] The ophthalmic liquid preparation according to Item 1, wherein the vitamin is at least one selected from the group consisting of vitamin A, vitamin B, and vitamin E.
[3] The ophthalmic liquid preparation according to Item 2, wherein the vitamin A is retinol palmitate.
[4] The ophthalmic liquid preparation according to Item 2, wherein the B vitamins are at least one selected from flavin adenine dinucleotide sodium, cyanocobalamin, pyridoxine and/or a salt thereof, panthenol, and pantothenic acid and/or a salt thereof.
[5] The ophthalmic liquid preparation according to Item 2, wherein the vitamin E compound is d-α-tocopherol acetate.
[6] The ophthalmic liquid formulation according to Item 2, wherein the concentrations of vitamins are as follows: flavin adenine dinucleotide sodium 0.01 to 0.05 w/v %, cyanocobalamin 0.004 to 0.02 w/v %, vitamin A's 10,000 units/100 ml to 50,000 units/100 ml, pyridoxine and/or a salt thereof 0.01 to 0.1 w/v %, panthenol and pantothenic acid and/or a salt thereof 0.01 to 0.1 w/v %, and vitamin E's 0.005 to 0.05 w/v %.

Furthermore, as one embodiment of the present invention, there is provided a photostabilization method as described below.
[7] A method for photostabilizing vitamins in an ophthalmic liquid preparation, comprising blending 0.01 to 0.05 w/v % of brimonidine and/or a salt thereof in the ophthalmic liquid preparation containing vitamins.

Furthermore, as one embodiment of the present invention, there is provided the following light stabilizer.
[8] A photostabilizer for vitamins in an ophthalmic liquid preparation, which is used in an ophthalmic liquid preparation containing vitamins, and which comprises 0.01 to 0.05 w/v % of brimonidine and/or a salt thereof.

Furthermore, as one embodiment of the present invention, there is provided a method for thermal stabilization as described below.
[9] A method for thermal stabilization of vitamins in an ophthalmic liquid preparation, comprising blending 0.01 to 0.05 w/v % of brimonidine and/or a salt thereof in the ophthalmic liquid preparation containing vitamins.

Furthermore, as one embodiment of the present invention, there is provided the following heat stabilizer.
[10] A thermal stabilizer for vitamins in an ophthalmic liquid preparation, which is used in an ophthalmic liquid preparation containing vitamins, characterized by comprising 0.01 to 0.05 w/v % of brimonidine and/or a salt thereof.

Furthermore, as one embodiment of the present invention, there is provided a method for promoting conjunctival migration as described below.
[11] A method for promoting the conjunctival transfer of brimonidine and/or a salt thereof via ophthalmic administration, comprising blending a vitamin with an ophthalmic liquid preparation containing 0.01 to 0.05 w/v % brimonidine and/or a salt thereof.

Furthermore, as one embodiment of the present invention, there is provided the conjunctival migration promoter shown below.
[12] A conjunctival transfer promoter for brimonidine and/or a salt thereof when administered by eye drop, comprising a liquid ophthalmic preparation containing 0.01 to 0.05 w/v % brimonidine and/or a salt thereof and a vitamin added thereto.

According to the present invention, an ophthalmic liquid formulation containing low concentrations of brimonidine and vitamins exhibits at least one of the following effects: improved stability of the vitamins against light or heat, and improved conjunctival transport of brimonidine.

Unless otherwise specified, terms used herein are understood to have the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Numerical ranges specified herein are intended to include their lower and upper limits.

(definition)
As used herein, "brimonidine" refers to a compound having the IUPAC name: 5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)quinoxalin-6-amine. Furthermore, unless otherwise specified, the concentrations of brimonidine and/or its salts are those calculated as brimonidine tartrate.

As used herein, "low concentration brimonidine" refers to brimonidine at a concentration of 0.05 w/v% or less.

In this specification, "vitamins" is a general term for organic compounds other than carbohydrates, proteins, and lipids that are necessary in trace amounts for the survival or growth of living organisms and that cannot be synthesized in sufficient amounts within the organism's body.

As used herein, an "ophthalmic liquid preparation" refers to an aqueous liquid preparation based on water.

As used herein, "photostability" refers to the degree to which the vitamin content in an ophthalmic liquid formulation is maintained after the formulation is exposed to a certain amount of light.

As used herein, "photostabilization" refers to inhibiting the decrease in vitamin content in an ophthalmic liquid formulation due to exposure to a certain amount of light, thereby maintaining a higher vitamin retention rate. For example, when an ophthalmic liquid formulation containing vitamins is filled into a colorless glass ampoule and exposed to 100,000 lx·hr of white light, photostabilization means that the vitamin content is maintained, i.e., the vitamin retention rate is higher, compared to a formulation that does not contain brimonidine.

As used herein, the term "photostabilization method" refers to a method used to prevent the decrease in vitamin content in an ophthalmic liquid formulation due to exposure to a certain amount of light, and to maintain a higher residual rate of vitamins.

As used herein, the term "photostabilizer" refers to an agent that is added to prevent the decrease in vitamin content in ophthalmic liquid formulations due to exposure to a certain amount of light, and to maintain a higher residual rate of vitamins.

As used herein, "thermal stability" refers to the degree to which the vitamin content in an ophthalmic liquid formulation is maintained after the formulation has been stored at a certain temperature for a certain period of time.

As used herein, "thermal stabilization" refers to inhibiting the decrease in vitamin content in an ophthalmic liquid formulation due to storage at a constant temperature for a certain period of time, and maintaining a higher vitamin retention rate. For example, thermal stabilization means that an ophthalmic liquid formulation containing vitamins is filled into a colorless glass ampoule and stored at 80°C for three days or one week, or at 70°C for one week, and then the vitamin content is maintained, i.e., the vitamin retention rate is higher, compared to a formulation that does not contain brimonidine.

As used herein, "thermal stabilization method" refers to a method used to prevent the decrease in vitamin content in an ophthalmic liquid formulation due to storage at a certain temperature for a certain period of time, and to maintain a high residual rate of vitamins.

As used herein, the term "photostabilizer" refers to an agent that is added to prevent the decrease in vitamin content in ophthalmic liquid preparations due to storage at a certain temperature for a certain period of time, and to maintain a high residual rate of vitamins.

As used herein, "conjunctival penetration" is an index that indicates the ease with which brimonidine in an ophthalmic liquid formulation administered by eye drop penetrates the conjunctiva, which is the site of action.

As used herein, the term "method for promoting conjunctival delivery" refers to a method carried out to increase the amount of brimonidine delivered to the conjunctiva, the site of action, in an ophthalmic liquid formulation administered by eye drop.

As used herein, the term "conjunctival transport promoter" refers to an agent incorporated to increase the amount of brimonidine transported to the conjunctiva, the site of action, in an ophthalmic liquid formulation administered by eye drop.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will be described below. The embodiments provided below are provided for a better understanding of the present invention, and it is understood that the scope of the present invention should not be limited to the following description. Therefore, it is clear that those skilled in the art can make appropriate modifications within the scope of the present invention in consideration of the description in this specification. It is also understood that the following embodiments can be used alone or in combination.

The ophthalmic liquid formulation of the present invention contains brimonidine and/or a salt thereof. Pharmaceutically acceptable salts of brimonidine include any salt. Pharmaceutically acceptable salts of brimonidine include hydrochloride, sulfate, phosphate, acetate, citrate, oxalate, malonate, salicylate, malate, fumarate, succinate, ascorbate, maleate, methanesulfonate, tartrate, and other inorganic carboxylates known to those skilled in the art, preferably tartrate.

In the present invention, low-concentration brimonidine refers to brimonidine at a concentration of 0.05 w/v% or less. For example, the upper limit of the concentration may be 0.04 w/v% or 0.03 w/v% in order to prevent side effects. The lower limit of the concentration is not limited as long as brimonidine is contained, but 0.01 w/v% may be used. For example, in consideration of the effects of this drug, 0.015 w/v% or 0.02 w/v% may be used.

Additives that can be incorporated into the ophthalmic liquid formulation of the present invention include vitamins. Vitamins are broadly divided into water-soluble vitamins and fat-soluble vitamins. Water-soluble vitamins include B vitamins and vitamin C (ascorbic acid). Fat-soluble vitamins include vitamins A, D, E, and K. The over-the-counter drug manufacturing (import) approval standards stipulate the vitamins that can be incorporated into eye drops, and from this perspective, vitamins A, B, and E are particularly preferred.

Vitamin A compounds include retinol and related substances. Retinol-related substances include retinal, retinoic acid, retinol palmitate, and other retinoids, such as isotretinoin, alitretinoin, acitretin, etretinate, adapalene, tazarotene, and bexarotene. Retinol palmitate and retinol acetate are preferred for use in eye drops. Vitamin A compounds act on epithelial cells to induce their proliferation, and therefore can be incorporated into eye drops for purposes such as corneal and conjunctival protection. They can also be incorporated into eye drops for the treatment of ophthalmic diseases such as night blindness, conjunctival xerosis, corneal xerosis, and keratomalacia. The content of vitamin A compounds can be expressed as vitamin A potency. When vitamin A is used, it is preferably incorporated at 100 to 300,000 units/100 ml, more preferably 10,000 to 50,000 units/100 ml. From the perspective of efficacy, the vitamin A compound contained in the eye drops may be used at 15,000 units or more, or at 20,000 units or more. From the perspective of preventing side effects, the vitamin A compound contained in the eye drops may be used at 30,000 units or less.

B vitamins include vitamin B1 (thiamine, etc.), vitamin B2, vitamin B3 (niacin, etc.), vitamin B5, vitamin B6, vitamin B7 (biotin, etc.), vitamin B9 (folic acid, etc.), and vitamin B12. Vitamins also include derivatives such as provitamins and pharmaceutically acceptable salts. Of the B vitamins, vitamins B2, B5, B6, and B12 are preferred, particularly from the perspective of being incorporated into eye drops.

Vitamin B2 includes riboflavin, riboflavin phosphate, riboflavin butyrate, riboflavin acetate, flavin adenine dinucleotide, flavin mononucleotide, and pharmaceutically acceptable salts thereof. Examples of salts include sodium and potassium salts. Flavin adenine dinucleotide sodium is preferred for use in eye drops. Vitamin B2 is directly involved in oxidation-reduction reactions, and when used in eye drops, it promotes the enzymatic respiratory metabolism of corneal and conjunctival cells, providing protection for the cornea and conjunctiva. Vitamin B2 can also be incorporated into eye drops to treat keratitis suspected to be caused by vitamin B2 deficiency or metabolic disorders. When vitamin B2 is used, it is preferably incorporated at 0.001-0.5 w/v%, more preferably 0.01-0.05 w/v%. To maximize efficacy, vitamin B2 may be used at 0.015 w/v% or more, or even 0.02 w/v% or more. To suppress side effects, it may be used at 0.04 w/v% or less, 0.03 w/v% or less, or 0.02 w/v% or less.

Examples of vitamin B5 include panthenol, pantothenic acid, or derivatives or salts thereof. In addition to panthenol and pantothenic acid, examples of derivatives or salts thereof include pantethine, pantetheine, pantothenyl alcohol, pantothenyl ethyl ether, pantetheine pantothenyl alcohol, calcium pantothenate, and sodium pantothenate. For use as eye drops, panthenol, calcium pantothenate, and sodium pantothenate are preferred as vitamin B5. When vitamin B5 is used, it is preferably formulated at 0.001 to 1 w/v%, more preferably 0.01 to 0.1 w/v%. To maximize efficacy, vitamin B5 may be used at 0.02 w/v% or more, or at 0.03 w/v% or more. To minimize side effects, it may be used at 0.08 w/v% or less, or at 0.05 w/v% or less.

Examples of vitamin B6 include pyridoxal, pyridoxamine, pyridoxine, and pharmaceutically acceptable salts thereof. Pyridoxine hydrochloride is preferred for use as an eye drop. Vitamin B6 is involved in protein metabolism as a coenzyme for amino acid decarboxylase and aminotransferase in the body, and can be incorporated into eye drops to alleviate eye fatigue. When vitamin B6 is used, it is preferably incorporated at 0.001 to 1 w/v%, more preferably 0.01 to 0.1 w/v%. To maximize efficacy, vitamin B6 may be used at 0.02 w/v% or more, or at 0.03 w/v% or more. To minimize side effects, it may be used at 0.08 w/v% or less, or at 0.07 w/v% or less.

Vitamin B12 is a compound with a structure in which cobalt is coordinated to a corrin ring. Specific examples include cyanocobalamin, mecobalamin (methylcobalamin), hydroxocobalamin, adenosylcobalamin, hydroxocobalamin hydrochloride, and hydroxocobalamin acetate. Vitamin B12 can be incorporated into eye drops for its pharmacological effects, such as alleviating tired eyes and eye strain. When vitamin B12 is used, it is preferably incorporated at 0.001-0.1 w/v%, more preferably 0.004-0.02 w/v%. From the perspective of efficacy, vitamin B12 may be used at 0.008 w/v% or more, or at 0.01 w/v% or more. From the perspective of suppressing side effects, it may be used at 0.015 w/v% or less, or at 0.01 w/v% or less.

Examples of vitamin E include tocopherol, tocotrienol, tocophersolan, and derivatives thereof. Tocopherol and tocotrienol may be α-, β-, γ-, or δ-tocopherol, and may be either the d- or dl-isomer. For use as eye drops, examples include d-α-tocopherol acetate and dl-α-tocopherol acetate. When vitamin E is used, it is preferably formulated at 0.0005 to 1 w/v%, more preferably 0.005 to 0.05 w/v%. To maximize efficacy, vitamin E may be used at 0.01 w/v% or more, or 0.02 w/v% or more. To reduce side effects, it may be used at 0.04 w/v% or less, 0.03 w/v% or less, or 0.02 w/v% or less.

Examples of vitamin C include ascorbic acid or its salts. Examples of vitamin D include vitamin D2 (ergosterol, ergocalciferol), D3 (7-dehydrocholesterol), previtamin D3 (cholecalciferol, 25-hydroxycholecalciferol, calcitriol (1,25-dihydroxycholecalciferol), calcitronic acid), vitamin D4 (dihydroergocalciferol), and vitamin D5 (dihydrotachysterol, calcipotriol, tacalcitol, paricalcitol). Examples of vitamin K include phylloquinone (K1), menaquinone (K2), and menadione (K3).

In the present invention, vitamins in ophthalmic preparations exert the physiological effects normally exhibited by each component, while in liquid ophthalmic preparations containing brimonidine or a salt thereof, they also enhance the conjunctival transport of brimonidine or a salt thereof.

The conjunctiva is a membrane that covers the sclera, the white of the eye, and lines the inside of the eyelid. It is primarily composed of conjunctival epithelial cells. The epithelial layer of the conjunctiva contains blood vessels, fibrous tissue, and lymphatic vessels. It contacts the cornea at the boundary between the white and black of the eye, and the cornea and conjunctiva constitute the outermost layer of the eye exposed to the outside world. Because the conjunctiva is exposed to the outside world, it is susceptible to infection by bacteria and viruses, and inflammation. Even when inflammation is not present, lack of sleep or overuse of the eyes can increase blood flow to supply oxygen and nutrients to the eyes, causing congestion. In order for brimonidine to exert its effect of reducing redness or whitening the eyes in the present invention, the active ingredient of the instilled formulation must reach and act on the capillaries in the conjunctiva.

Conjunctival penetration is an index that indicates the ease with which the active ingredient of an ophthalmic liquid formulation administered by eye drops penetrates the conjunctiva, the site of action. Corneal epithelial cells and conjunctival epithelial cells form tight junctions between each other, forming hydrophobic membranes originating from the cell membrane. This restricts the permeation of water-soluble drugs through the cornea and conjunctiva. The penetration of an instilled drug into the eye via the cornea or conjunctiva is determined by measuring the drug concentration in the aqueous humor and in the conjunctival tissue after instillation. However, measuring ocular penetration in humans is difficult, so analysis is performed using predictive models based on animal experiments. A simple method for measuring ocular penetration is based on the octanol/water partition coefficient. The octanol/water partition coefficient can be used to evaluate not only ocular penetration but also conjunctival penetration.

In the present invention, the ophthalmic liquid formulation is an aqueous liquid formulation primarily based on water, but may further contain any liquid base that can be used in eye drops. The ophthalmic liquid formulation of the present invention is prepared to have a pH and osmolality acceptable for eye drops. The pH of the ophthalmic liquid formulation can be adjusted to 5.0 to 9.0 using a pH adjuster, for example, 5.5 to 8.5. For example, it can also be adjusted to 6.0 to 8.0. The amounts of components added to the ophthalmic liquid formulation are adjusted so that the osmolality ratio of the ophthalmic liquid formulation is preferably 0.5 to 2.5, and more preferably 0.7 to 1.5.

The ophthalmic liquid preparation of the present invention is preferably an eye drop. The ophthalmic liquid preparation of the present invention may be a liquid preparation that relieves or suppresses eye redness. Relieving or suppressing eye redness refers to increasing the whiteness of the whites of the eyes, which can also be referred to as eye whitening.

Light-blocking containers can be used for liquid preparations with low photostability. However, eye drops are intended to be used for a certain period of time after opening. If light-blocking containers are used for eye drops, it becomes difficult to check the remaining amount or any abnormalities in the contents, so it is desirable to use transparent containers for eye drops. Therefore, it is important to provide preparations with high photostability. Colored transparent containers can also be used instead of light-blocking containers.

The ophthalmic liquid formulation of the present invention can contain any ingredient that can be used in eye drops, provided that the effects of the present invention are not impaired. In addition to brimonidine tartrate, the active ingredient of the present invention, the formulation may contain any active ingredient and additives. Examples of such ingredients include, but are not limited to, decongestants, focusing function improvers, anti-inflammatory/astringent agents, antihistamines, vitamins, nutritional ingredients, sulfonamides, preservatives, pH adjusters, isotonicity agents, thickeners, antioxidants, solubilizers, stabilizers, surfactants, fragrances, and refreshing agents. These active ingredients and additives may be used singly or in combination from each category.

Decongestant agents that can be used include epinephrine, ephedrine, tetrahydrozoline, naphazoline, phenylephrine, methylephedrine, or salts thereof.

Neostigmine methylsulfate can be used as an accommodative agent.

Examples of anti-inflammatory and astringent agents that can be used include ε-aminocaproic acid, allantoin, berberine or its salts, azulene sulfonic acid or its salts, glycyrrhizic acid or its salts, zinc sulfate, zinc lactate, and lysozyme chloride.

Diphenhydramine hydrochloride and chlorpheniramine maleate may be used as antihistamines.

As moisture-retaining and nutrient-retaining components, amino acids or their salts, and sodium chondroitin sulfate ester can be used. As for amino acids or their salts, "amino acids" refers not only to amino acids but also to substances that have a sulfate group instead of the carboxyl group of an amino acid, such as taurine. Examples of amino acids include glycine, alanine, methionine, valine, threonine, glutamine, glutamic acid, asparagine, aspartic acid, cysteine, histidine, isoleucine, leucine, lysine, phenylalanine, tryptophan, arginine, proline, tyrosine, and serine. Preferred amino acids include aspartic acid, methionine, and glycine. Amino acids other than glycine may be L-amino acids, D-amino acids, or DL-amino acids.

Sulfa drugs that can be used include sulfamethoxazole, sulfamethoxazole sodium, sulfisoxazole, and sulfisomidine sodium.

Preservatives that can be used include methyl parahydroxybenzoate, ethyl parahydroxybenzoate, propyl parahydroxybenzoate, butyl parahydroxybenzoate, oxyquinoline sulfate, benzalkonium chloride, chlorobutanol, sodium chlorite, benzododecinium bromide, chlorhexidine gluconate, sorbate, sodium dehydroacetate, benzoate, benzyl alcohol, alkylpolyaminoethylglycine, boric acid, and borax.

As pH adjusters, buffers such as citrate buffer, acetate buffer, carbonate buffer, borate buffer, and phosphate buffer can be used, as well as acids such as hydrochloric acid, acetic acid, boric acid, carbonic acid, sulfuric acid, phosphoric acid, citric acid, and tartaric acid, and bases such as sodium hydroxide, sodium bicarbonate, sodium carbonate, triethanolamine, and monoethanolamine.

Examples of isotonic agents include sugars and salts. Examples of salts that can be used include sodium bisulfite, sodium sulfite, potassium chloride, calcium chloride, sodium chloride, magnesium chloride, potassium acetate, sodium acetate, sodium bicarbonate, sodium carbonate, sodium thiosulfate, magnesium sulfate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate. Sugars that can be used include any monosaccharide or polysaccharide, such as glucose, cyclodextrin, xylitol, sorbitol, and mannitol.

Thickening agents that can be used include sodium chondroitin sulfate, polyvinyl alcohol, carboxyvinyl polymer, hydroxyethyl cellulose, hydroxypropyl methylcellulose, methylcellulose, alginic acid, hyaluronic acid, polyvinylpyrrolidone, and salts thereof.

Solubilizing agents that can be used include nonionic surfactants such as polyoxyethylene sorbitan monooleate, polyoxyethylene hydrogenated castor oil, tyloxapol, and Pluronic; and polyhydric alcohols such as glycerin and macrogol.

Examples of stabilizers that can be used include polyvinylpyrrolidone, sulfites, monoethanolamine, glycerin, propylene glycol, polyethylene glycol, cyclodextrin, dextran, ascorbic acid, edetate, taurine, and tocopherol.

Surfactants that can be used include, for example, nonionic surfactants such as tyloxapol, polyoxyethylene hydrogenated castor oil, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene sorbitan fatty acid ester, and octoxynol; amphoteric surfactants such as alkyldiaminoethylglycine and lauryldimethylaminoacetic acid betaine; anionic surfactants such as alkyl sulfates, N-acyltaurine salts, polyoxyethylene alkyl ether phosphates, and polyoxyethylene alkyl ether sulfates; and cationic surfactants such as alkylpyridinium salts and alkylamine salts.

Fragrances or freshening agents that can be used include menthol, ethanol, camphor, geraniol, borneol, menthol, lycium globulus, fennel oil, cool mint oil, spearmint oil, peppermint water, peppermint oil, bergamot oil, eucalyptus oil, and rose oil.

The optional ingredients mentioned above may be used for purposes other than those listed above. For example, ethanol, which is used as a cooling agent, may also be added to ophthalmic solutions as a preservative.

All documents cited herein are incorporated by reference in their entirety.

The examples of the present invention described below are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the claims. Modifications to the present invention, such as additions, deletions, and substitutions of constituent elements of the present invention, may be made without departing from the spirit of the present invention.

Test Example 1: Photostability test of flavin adenine dinucleotide sodium 1. Preparation of ophthalmic solutions Purified water was added to boric acid (Fujifilm Wako Pure Chemical Industries, Ltd.) to dissolve, brimonidine tartrate (Hinewy Pharma. Tech. Co., Ltd.) and flavin adenine dinucleotide sodium (Alfa Aesar) were added, and the pH was adjusted to 5.5 to 8.5 using hydrochloric acid and aqueous sodium hydroxide to prepare solutions having the compositions shown in Tables 1 to 3, thereby obtaining ophthalmic solutions. Note that the values in the tables are in w/v %, excluding pH and residual rate.

2. Method for Evaluating the Light Stability of Flavin Adenine Dinucleotide Sodium: 5 mL of the ophthalmic solution obtained above was added to a glass ampoule and exposed to white light at 100,000 lx·hr to obtain a degraded product. The concentrations of flavin adenine dinucleotide sodium in the samples stored at room temperature for one week and in the degraded samples were measured using a high-performance liquid chromatography system (HPLC, manufactured by Shimadzu Corporation) under the conditions shown below, and the residual rate (%) of flavin adenine dinucleotide sodium was calculated according to the following formula. The results, along with the composition of each formulation, are shown in Tables 1 to 3.

<High-performance liquid chromatography conditions>
Column: 4.6 mm inner diameter x 15 cm length, octadecylsilylated silica gel ("Unicil QC18" manufactured by GL Sciences)
Detector: ultraviolet absorption photometer (measurement wavelength: 350 nm)
Column temperature: 40°C
Mobile phase: potassium dihydrogen phosphate solution (1 → 500) / methanol mixture for liquid chromatography (750/250)
Flow rate: Approximately 0.5mL/min

<Residual rate of flavin adenine dinucleotide sodium>
The residual rate (%) of flavin adenine dinucleotide sodium was calculated according to the following formula:

In Examples 1 to 8 above, the addition of brimonidine tartrate improved the photostability of flavin adenine dinucleotide sodium. Furthermore, the residual rate improved by 4.4 to 17.4% compared to Comparative Examples 1 to 6.

Test Example 2: Thermal stability test of cyanocobalamin 1. Preparation of eye drops Purified water was added to boric acid (Fujifilm Wako Pure Chemical Industries, Ltd.) to dissolve, and brimonidine tartrate (Hinewy Pharma. Tech. Co., Ltd.) and cyanocobalamin (Fujifilm Wako Pure Chemical Industries, Ltd.) were added. The pH was adjusted to 5.5 to 8.5 using hydrochloric acid and aqueous sodium hydroxide solution to prepare solutions having the compositions shown in Tables 4 to 6, and eye drops were obtained. Note that the values in the tables are in w/v %, excluding pH and residual rate.

2. Method for Evaluating the Thermal Stability of Cyanocobalamin Five mL of the ophthalmic solution obtained above was added to a glass ampoule and stored in a thermostatic chamber at 80°C for one week to obtain a degraded product. The cyanocobalamin concentrations in the product stored at room temperature for four weeks and in the degraded product were measured using a high-performance liquid chromatography system (HPLC, manufactured by Shimadzu Corporation) under the conditions shown below, and the residual rate (%) of cyanocobalamin was calculated according to the following formula. The results, along with the composition of each formulation, are shown in Tables 4 to 6.

<High-performance liquid chromatography conditions>
Column: 4.6 mm inner diameter x 15 cm length, octadecylsilylated silica gel (AA12S05-1506WT, manufactured by YMC Co., Ltd.)
Detector: ultraviolet absorption photometer (measurement wavelength: 278 nm)
Column temperature: 40°C
Mobile phase: Dissolve 5.175 g of ammonium dihydrogen phosphate in 900 mL of water, and add 100 mL of acetonitrile for liquid chromatography.
Flow rate: Approximately 1 mL/min

<Residual rate of cyanocobalamin>
The residual rate (%) of cyanocobalamin was calculated according to the following formula:

In Examples 9 to 16 above, the addition of brimonidine tartrate improved the thermal stability of cyanocobalamin in the pH range of 6.5 to 7.5. Furthermore, the residual rate improved by 0.8 to 5.2% compared to Comparative Examples 7 to 12.

Test Example 3: Thermal Stability Test of d-α-Tocopherol Acetate 1. Preparation of Eye Drops Boric acid (Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in purified water, and brimonidine tartrate (Hinewy Pharma. Tech. Co., Ltd.) and d-α-tocopherol acetate (Combi-Blocks) were added. The pH was adjusted to 5.5-8.5 using hydrochloric acid and aqueous sodium hydroxide to prepare solutions with the compositions shown in Tables 7 and 8, and eye drops were obtained. The values in the tables are in w/v %. When d-α-tocopherol acetate was added, it was added in a state mixed with polyoxyethylene hydrogenated castor oil 60 (Nikko Chemicals) that had been dissolved by heating. The values in the tables are in w/v % except for pH and residual rate.

2. Method for Evaluating the Thermal Stability of d-α-Tocopherol Acetate Five mL of the eye drops obtained above was added to a glass ampoule and stored in a thermostatic chamber at 70°C for one week to obtain a degraded product. The concentrations of d-α-tocopherol acetate in the samples stored at room temperature for four weeks and in the degraded samples were measured using a high-performance liquid chromatography system (HPLC, manufactured by Shimadzu Corporation) under the conditions shown below, and the residual rate (%) of d-α-tocopherol acetate was calculated according to the following formula. The results, along with the composition of each formulation, are shown in Tables 7 and 8.

<High-performance liquid chromatography conditions>
Column: 4.6 mm inner diameter x 15 cm length, octylsilanized silica gel ("OC12S05-1546WT", manufactured by YMC Co., Ltd.)
Detector: ultraviolet absorption photometer (measurement wavelength: 284 nm)
Column temperature: 40°C
Mobile phase: Acetonitrile/water/phosphoric acid mixture (930/69/1) for liquid chromatography
Flow rate: Approximately 1 mL/min

<Residual rate of d-α-tocopherol acetate>
The residual rate (%) of d-α-tocopherol acetate was calculated according to the following formula:

In Examples 17 to 22 above, the addition of brimonidine tartrate improved the thermal stability of d-α-tocopherol acetate in the pH range of 6.5 to 8.5. Furthermore, the residual rate improved by 9.9 to 36.9% compared to Comparative Examples 13 to 16.

Test Example 4: Photostability test of pyridoxine hydrochloride 1. Preparation of ophthalmic solutions Purified water was added to trometamol (Fujifilm Wako Pure Chemical Industries, Ltd.) to dissolve it, and brimonidine tartrate (Hinewy Pharma. Tech. Co., Ltd.) and pyridoxine hydrochloride (Fujifilm Wako Pure Chemical Industries, Ltd.) were added. The pH was adjusted to 5.5 to 8.5 using hydrochloric acid and aqueous sodium hydroxide solution to prepare solutions having the compositions shown in Tables 9 to 11, and ophthalmic solutions were obtained. The values in the tables are in w/v %, excluding pH and residual rate.

2. Evaluation method for photostability of pyridoxine hydrochloride 5 mL of the ophthalmic solution obtained above was placed in a glass ampoule and exposed to white light at 100,000 lx·hr to obtain a deteriorated sample. The pyridoxine hydrochloride concentrations in the sample stored at room temperature for one week and the deteriorated sample were measured using a high-performance liquid chromatograph (HPLC, manufactured by Shimadzu Corporation) under the following conditions, and the residual rate (%) of pyridoxine hydrochloride was calculated according to the following formula:

<High-performance liquid chromatography conditions>
Column: 4.6 mm inner diameter x 15 cm length, octadecylsilylated silica gel (AA12S05-1546WT, manufactured by YMC Co., Ltd.)
Detector: ultraviolet absorption photometer (measurement wavelength: 290 nm)
Column temperature: 40°C
Mobile phase: 400 mL of acetonitrile for liquid chromatography and 2 g of sodium lauryl sulfate were added to 600 mL of 0.05 mol/L potassium dihydrogen phosphate test solution, and then phosphoric acid was added to adjust the pH to 3.5.
Flow rate: Approximately 1 mL/min

<Residual rate of pyridoxine hydrochloride>
The residual rate (%) of pyridoxine hydrochloride was calculated according to the following formula.


In Examples 23 to 30, the addition of brimonidine tartrate improved the photostability of pyridoxine hydrochloride in the pH range of 5.5 to 7.5. The residual rate was improved by 0.7 to 5.4% compared to Comparative Examples 17 to 22.

Test Example 5: Thermal stability test of panthenol 1. Preparation of eye drops Purified water was added to boric acid (Fujifilm Wako Pure Chemical Industries, Ltd.) to dissolve, and brimonidine tartrate (Hinewy Pharma. Tech. Co., Ltd.) and panthenol (Fujifilm Wako Pure Chemical Industries, Ltd.) were added. The pH was adjusted to 5.5 to 8.5 using hydrochloric acid and aqueous sodium hydroxide to prepare solutions having the compositions shown in Tables 12 to 14, thereby obtaining eye drops. Note that the values in the tables are in w/v %, excluding pH and residual rate.

2. Evaluation method for thermal stability of panthenol 5 mL of the eye drops obtained above was added to a glass ampoule and stored in a thermostatic bath at 80°C for 3 days to obtain a deteriorated product. The panthenol concentrations in the product stored at room temperature for 4 weeks and the deteriorated product were measured using a high-performance liquid chromatograph system (HPLC, manufactured by Shimadzu Corporation) under the conditions shown below, and the residual rate (%) of panthenol was calculated according to the following formula.

<High-performance liquid chromatography conditions>
Column: Guard column ("AA30S05-G304CC" manufactured by YMC) + 4.6 mm inner diameter x 15 cm length octadecylsilylated silica gel ("AA30S05-1546WT" manufactured by YMC)
Detector: ultraviolet absorption photometer (measurement wavelength: 220 nm)
Column temperature: 40°C
Mobile phase: 100 mL of liquid chromatography grade methanol was added to 900 mL of 0.05 mol/L potassium dihydrogen phosphate test solution, and then phosphoric acid was added to adjust the pH to 3.0.
Flow rate: Approximately 1 mL/min
<Panthenol Residual Rate>
The residual rate (%) of panthenol was calculated according to the following formula.


In Examples 31 to 38, the addition of brimonidine tartrate improved the thermal stability of panthenol in the pH range of 5.5 to 7.5. The residual rate was improved by 0.7 to 3.9% compared to Comparative Examples 23 to 28.

Test Example 6: Measurement of the amount of brimonidine tartrate distributed between the octanol layer and the aqueous layer (prescription) Each sample was prepared by a conventional method. Specifically, boric acid (Fujifilm Wako Pure Chemical Industries, Ltd.) and brimonidine tartrate (Hinewy Pharma. Tech. Co., Ltd.) were added to purified water and dissolved, followed by the addition of flavin adenine dinucleotide sodium (Alfa Aesar), cyanocobalamin (Fujifilm Wako Pure Chemical Industries, Ltd.), retinol palmitate (Fujifilm Wako Pure Chemical Industries, Ltd.), d-α-tocopherol acetate (Combi-Blocks), pyridoxine hydrochloride (Fujifilm Wako Pure Chemical Industries, Ltd.), or panthenol (Fujifilm Wako Pure Chemical Industries, Ltd.), and the pH was adjusted with a pH adjuster, followed by dilution with purified water. When retinol palmitate and d-α-tocopherol acetate were added, they were mixed with polyoxyethylene hydrogenated castor oil 60 (Nikko Chemicals) that had been dissolved by heating. The values in the table are w/v % except for the pH and retinol palmitate columns. Retinol palmitate is shown in activity units per 100 mL.

(Test operation)
The test solution and 1-octanol (Nacalai Tesque) were mixed according to the following procedure.
1) Plastic centrifuge tubes were filled with 2.5 mL of each test solution and 2.5 mL of 1-octanol saturated with water.
2) The mixture was mixed for 30 seconds using a vortex mixer (VX100, Labnet International).
3) The mixture was shaken for 30 minutes using a shaker (MW-1, AS ONE) that stirs the mixture up and down (300 times/min).
4) The mixture was shaken for 24 hours or more using a horizontally stirring rotary shaker (Universal Shaker SHK-U4, AGC Technoglass) (120 rpm/min).
5) The mixture was mixed for 30 seconds using a vortex mixer (VX100, Labnet International).
6) The octanol layer and the aqueous layer were separated by centrifugation (LC-120, Tomy Seiko) (3,000 rpm, 10 minutes), and the aqueous layer was collected and mixed to prepare the aqueous layer sample.

(Measurement of Brimonidine Tartrate Content in Test Solution and Aqueous Layer)
The brimonidine tartrate content of each test solution and the aqueous layer sample obtained after mixing each test solution with octanol was measured by high performance liquid chromatography (HPLC).
Column: 4.6 mm inner diameter x 75 mm length, octadecylsilylated silica gel ("Symmetry C18 3.5" manufactured by Waters)
Detector: UV-visible spectrophotometer Measurement wavelength: 264 nm
Mobile phase: 5.175 g of ammonium dihydrogen phosphate was dissolved in 900 mL of water, and 100 mL of acetonitrile for liquid chromatography was added.

The amount of brimonidine tartrate transferred to the octanol layer after mixing of each sample with octanol was calculated from the difference between the amount of brimonidine tartrate in each test solution measured and the amount of brimonidine tartrate in the aqueous layer of the sample after mixing. The increase rate (C _rate ) of the amount of brimonidine tartrate transferred to the octanol layer due to the addition of vitamins was calculated according to the following formula:
[In the formula, C _sample is the brimonidine tartrate content in the octanol layer of the sample after mixing, and C _{comparative example} is the brimonidine tartrate content in the octanol layer of the comparative example after mixing. Note that the C _sample and C _{comparative example} had the same brimonidine tartrate concentration.]

It has been found that by incorporating at least one vitamin selected from the group consisting of flavin adenine dinucleotide sodium, cyanocobalamin, retinol palmitate, d-α-tocopherol acetate, pyridoxine hydrochloride, and panthenol into a brimonidine tartrate solution, the amount of brimonidine tartrate transferred to the octanol layer is increased, and the lipid solubility of brimonidine tartrate is improved.

Test Example 7: Measurement of the amount of brimonidine tartrate transferred to rabbit conjunctiva (Formulation) Each sample was prepared by a standard method. Specifically, boric acid (Fujifilm Wako Pure Chemical Industries, Ltd.), borax (Nacalai Tesque), and brimonidine tartrate (Hinewy Pharma.Tech. Co., Ltd.) were added to purified water and dissolved, followed by the addition of d-α-tocopherol acetate or pyridoxine hydrochloride. The pH was adjusted with a pH adjuster, and the solution was diluted with purified water. When d-α-tocopherol acetate was added, it was added in a state where it was mixed with polyoxyethylene hydrogenated castor oil 60 (Nikko Chemicals) that had been dissolved by heating. The values in the table, excluding pH, are in w/v %.

(Test operation)
1-1) Tube 1: Four tubes for each group. The specimen was dispensed into 1 mL sample tubes (1.5 mL microtubes, Zaltostat).
1-2) Tube 2: Four sample tubes with filters (Ultrafree-MC-GV 0.45 μm, Millipore) were prepared for each group.
2) Rabbit eyeballs (Kitayama Labes) were obtained and the conjunctiva was excised.
3) The conjunctiva was washed by immersion in physiological saline (Otsuka saline injection, Otsuka Pharmaceutical Factory).
4) The moisture on the surface was gently wiped off with a Kimwipe, and the weight of the conjunctiva was measured.
5) After measuring the weight of the conjunctiva, the solution was placed in 1-1) Tube 1 and shaken at 1,500 rpm for 5 minutes using a shaker (Block Bath Shaker MyBL-100CS, AS ONE).
6) The conjunctiva was removed from the centrifuge tube in 5).
7) 300 μL of the sample was taken from the centrifuge tube in 6) after removing the conjunctiva, added to Tube 2 in 1-2), and centrifuged (15,000 rpm, 10 minutes, 4°C) in a tabletop high-speed microcentrifuge (CT-12RE, Hitachi Koki), and the filtrate was used as the sample.

(Determination of the amount transferred to the conjunctiva)
The brimonidine tartrate content of (i) the test solution without immersion in the conjunctiva and (ii) the specimen in 7) was measured by high performance liquid chromatography (HPLC), and the amount transferred to the conjunctiva per specimen was calculated from the difference between (i) and (ii). Furthermore, the content of brimonidine tartrate transferred per 1 g of conjunctiva for each individual was calculated from the conjunctival weight measured in 4), and the average value of the four specimens was used as the amount transferred to the conjunctiva.
The rate of increase (C _rate ) in the amount of brimonidine tartrate transferred to the conjunctiva by the addition of d-α-tocopherol acetate or pyridoxine hydrochloride was calculated according to the following formula.
[In the formula, C _sample is the conjunctival transfer amount of brimonidine tartrate in the example, and C _{comparative example 35} is the conjunctival transfer amount of brimonidine tartrate in comparative example 35.]

Of the combinations that showed improved transferability (lipid solubility) to the octanol layer in Test Example 6, the representative combinations d-α-tocopherol acetate and pyridoxine hydrochloride were used to examine actual transferability to the conjunctiva. Similar to the results for transferability to the octanol layer, the amount of brimonidine transferred to the conjunctiva was improved. Therefore, it can be assumed that other vitamins that showed improved transferability to the octanol layer in Test Example 6 will also have improved transferability to the conjunctiva.

Claims (2)

An ophthalmic liquid preparation containing 0.01 to 0.05 w/v % brimonidine and/or a salt thereof and d-α-tocopherol acetate . 2. The ophthalmic liquid preparation according to claim 1 , wherein the concentration of d-α-tocopherol acetate is 0.005 to 0.05 w/v %.