Cosmetic composition and method for inhibiting crystallization of readily crystallizable water-soluble active ingredient in cosmetic composition

Abstract

To provide a technique for stably incorporating an easily crystallizable water-soluble active ingredient exhibiting functionality for the skin into a composition for a cosmetic.SOLUTION: There is provided a composition for a cosmetic which is a high internal phase W / O emulsion composition which comprises (a) an emulsifier, (B) oil, (C) water and (D) an easily crystallizable water-soluble active ingredient, wherein the ratio of the water phase is 70 mass% or more of a high internal phase W / O emulsion composition. In addition, there is provided a method for inhibiting crystallization of an easily crystallizable water-soluble active ingredient in a composition for a cosmetic so that the easily crystallizable water-soluble active ingredient is incorporated into the water phase of a composition for a cosmetic composed of a high internal phase W / O emulsion composition in which the ratio of a water phase is 70 mass% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cosmetic composition containing a readily crystallizable water-soluble active ingredient that exhibits functionality on the skin, and a method for inhibiting crystallization of the readily crystallizable water-soluble active ingredient contained in such a cosmetic composition. [Background technology]

[0002] Ingredients that exhibit functionality on the skin are known, such as vitamin C or its derivatives, vitamin E or its derivatives, vitamin A or its derivatives, glycyrrhizic acid or its derivatives, tranexamic acid or its derivatives, various moisturizers, whitening agents, anti-inflammatory agents, anti-acne agents, anti-wrinkle agents, antioxidants, etc. These have traditionally been incorporated into quasi-drugs and cosmetics to act on the skin (Non-Patent Document 1). However, some of these functional ingredients tend to crystallize in the formulation, causing problems with the stability of product quality.

[0003] On the other hand, so-called high internal phase W / O emulsion compositions are known, which are W / O emulsion compositions in which an aqueous phase is dispersed in an oil phase, and in which the ratio of the dispersed phase made of an aqueous phase to the continuous phase made of an oil phase is equal to or greater than a predetermined value (see Patent Document 1). Generally, the advantage of high internal phase W / O emulsion compositions is that they can provide both a refreshing feel when used and a high moisturizing effect when used for cosmetics, etc. However, disadvantages include the difficulty of maintaining the emulsion state and low stability over time. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] New Cosmetics Handbook (2006) Nikko Chemicals [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 57-81827 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a technique for stably incorporating a readily crystallizable water-soluble active ingredient that exhibits functionality on the skin into a cosmetic composition. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to achieve the above-mentioned object and have found that a W / O type emulsion composition, particularly a high internal phase W / O type emulsion composition, can inhibit the crystallization of a readily crystallizable water-soluble active ingredient, thereby completing the present invention.

[0008] That is, the first aspect of the present invention provides a cosmetic composition characterized by being a high internal phase W / O type emulsion composition containing (A) an emulsifier, (B) oil, (C) water, and (D) a readily crystallizable water-soluble active ingredient, in which the proportion of the aqueous phase is 70% by mass or more.

[0009] The cosmetic composition uses a high internal phase W / O emulsion composition in which the proportion of the aqueous phase is 70% by mass or more, so even when a readily crystallizable water-soluble active ingredient is included, the crystallization of the active ingredient is suppressed, resulting in good formulation stability. Therefore, for example, it is possible to provide a cosmetic composition in the form of a cosmetic preparation that aims to achieve both a refreshing feel when used and a high moisturizing effect, and that also has excellent product quality stability.

[0010] In the above cosmetic composition, the (D) readily crystallizable water-soluble active ingredient preferably includes a vitamin C derivative.

[0011] In the cosmetic composition, the vitamin C derivative preferably includes one or more selected from the group consisting of magnesium ascorbyl phosphate, sodium ascorbyl phosphate, trisodium ascorbyl palmitate phosphate, and disodium isostearyl ascorbyl.

[0012] In the cosmetic composition, it is preferable that the content of the (D) easily crystallizable water-soluble active ingredient in the cosmetic composition is 0.2% by mass or more and 10.0% by mass or less, calculated as the dry solid content of the easily crystallizable water-soluble active ingredient.

[0013] The cosmetic composition preferably further contains an oil gelling agent.

[0014] The cosmetic composition preferably further contains a microbial fermentation product.

[0015] In the cosmetic composition, the proportion of the aqueous phase is preferably 75% by mass or more and 85% by mass or less.

[0016] On the other hand, the second aspect of the present invention provides a method for inhibiting crystallization of a readily crystallizable water-soluble active ingredient in a cosmetic composition, characterized by incorporating the readily crystallizable water-soluble active ingredient into the aqueous phase of the cosmetic composition, which is a high internal phase W / O type emulsion composition in which the aqueous phase accounts for 70 mass% or more.

[0017] According to the above method, a high internal phase W / O emulsion composition in which the proportion of the aqueous phase is 70% by mass or more is used, and therefore, even when a readily crystallizable water-soluble active ingredient is contained, the crystallization of the active ingredient is suppressed, resulting in good formulation stability. Therefore, for example, it is possible to provide a cosmetic composition in the form of a cosmetic intended to achieve both a refreshing feel when used and a high moisturizing effect, and which also has excellent product quality stability.

[0018] In the above method, the readily crystallizable water-soluble active ingredient preferably includes a vitamin C derivative.

[0019] In the above method, the vitamin C derivative preferably comprises one or more selected from the group consisting of magnesium ascorbyl phosphate, sodium ascorbyl phosphate, trisodium ascorbyl palmitate phosphate, and disodium isostearyl ascorbyl.

[0020] In the above method, it is preferable that the content of the readily crystallizable water-soluble active ingredient in the cosmetic composition is 0.2% by mass or more and 10.0% by mass or less, calculated as the dry solid content of the readily crystallizable water-soluble active ingredient.

[0021] In the above method, the cosmetic composition preferably further comprises an oil gelling agent.

[0022] In the above method, the cosmetic composition preferably further comprises a microbial fermentation product.

[0023] In the above method, the cosmetic composition preferably has an aqueous phase content of 75% by mass or more and 85% by mass or less. [Effects of the Invention]

[0024] According to the present invention, a high internal phase W / O emulsion composition in which the proportion of the aqueous phase is 70% by mass or more is used, and therefore, even when a readily crystallizable water-soluble active ingredient is contained, the crystallization of the active ingredient is suppressed, resulting in good formulation stability. Therefore, for example, it is possible to provide a cosmetic composition in the form of a cosmetic intended to achieve both a refreshing feel when used and a high moisturizing effect, and which also has excellent product quality stability. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a set of polarizing microscope photographs showing examples of the results of observation under a polarizing microscope after storing the preparation in Test Example 1 under various temperature conditions for three months and then observing the preparation under a polarizing microscope after the storage period. [Figure 2] Figure 2 shows the results of storing the preparation in Test Example 2 at 50°C for three months and then examining the residual rate of magnesium ascorbyl phosphate (VC-PMG), a vitamin C derivative, at the end of the storage period. [Figure 3] FIG. 3 is a set of polarizing microscope photographs showing examples of the results of observation under a polarizing microscope after storing the preparation in Test Example 3 under various temperature conditions for three months and then observing the preparation under a polarizing microscope after the storage period. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention relates to a technology using an emulsion composition with specific properties to improve the formulation stability of an active ingredient intended for application to the skin. More specifically, the present invention relates to a cosmetic composition comprising a high internal phase W / O emulsion composition containing a readily crystallizable water-soluble active ingredient. Herein, the term "easily crystallizable water-soluble active ingredient" refers to a component that exhibits some desired functionality on the skin and exhibits both readily crystallizable and water-soluble properties. "Water-soluble" refers to a component that has the property of being able to dissolve or disperse in the dispersed phase (the aqueous phase) of a high internal phase W / O emulsion composition and exist in an effective amount. "Easily crystallizable" refers to a component that has the property of easily forming crystals or the like when dissolved or dispersed in an aqueous solvent such as water. More specifically, "easily crystallizable" refers to a component that has the property of being at least partially solidified by the formation of crystals or the like when dissolved or dispersed in purified water and stored under specified conditions, typically at 40°C for 3 months or at 5°C for 3 months.

[0027] In the present invention, a high internal phase W / O emulsion composition is used as the cosmetic composition. Specifically, as shown in the examples below, when a readily crystallizable water-soluble active ingredient is incorporated into a high internal phase W / O emulsion composition, crystallization is suppressed, improving its pharmaceutical stability compared to other emulsion-type compositions or aqueous compositions. The proportion of the aqueous phase in a high internal phase W / O emulsion composition is typically 70% to 99% by mass, more typically 74% to 95% by mass, and even more typically 74% to 90% by mass. If the proportion of the dispersed phase consisting of the aqueous phase is less than the above range, it is undesirable because it may not provide the properties characteristic of a high internal phase W / O emulsion composition, such as a refreshing feel during use and high moisturizing effect. However, it is even more preferable that the proportion of the aqueous phase in a high internal phase W / O emulsion composition is 75% to 85% by mass. If the proportion of the aqueous phase is less than 75% by mass, the effect of suppressing the crystallization of the easily crystallizable water-soluble active ingredient tends to be poor, and as a result, the effect of improving the formulation stability tends to be poor. On the other hand, if the proportion of the aqueous phase exceeds 85% by mass, problems may arise in the stability of the emulsified state of the emulsion composition itself.

[0028] Generally, whether an emulsion composition forms a W / O emulsion in which an aqueous phase is dispersed in an oil phase can be determined by methods well known to those skilled in the art. For example, an emulsion is dropped into water in a test tube, and if no dispersion occurs, it is determined to be a W / O emulsion (dilution method). Alternatively, a W / O emulsion can be confirmed by, for example, contacting the electrode of a tester with the emulsion and measuring the electrical conductivity (electrical conductivity method). Furthermore, a W / O emulsion can be confirmed by adding a water- or oil-soluble dye and observing a microscope image (dye method).

[0029] The readily crystallizable water-soluble active ingredient (D) used in the present invention may be a component that has been conventionally applied to the skin, or may be a novel component, and is not particularly limited. Examples of components that have been conventionally applied to the skin include vitamin C derivatives such as magnesium ascorbyl phosphate, sodium ascorbyl phosphate, trisodium ascorbyl palmitate phosphate, and disodium isostearyl ascorbyl, cinnamic acid derivatives such as ferulic acid and arginine ferulate, phosphate compounds such as pyridoxine cyclic phosphate, adenosine phosphate, and adenosine triphosphate, polyphenols such as astaxanthin, anthocyanins, and isoflavones, and caffeine. These may be used alone or in combination of two or more.

[0030] The cosmetic composition according to the present invention will be described in more detail below. However, the cosmetic composition according to the present invention may be any composition as long as it has the properties of a high internal phase W / O emulsion composition in which the proportion of the aqueous phase is 70% by mass or more, as described above, and contains a readily crystallizable water-soluble active ingredient, and the preferred embodiments described below do not in any way limit the scope of the present invention.

[0031] In a preferred embodiment, the cosmetic composition according to the present invention comprises an emulsifier as component (A), an oil as component (B), water as component (C), and a readily crystallizable water-soluble active ingredient as component (D).

[0032] The emulsifier for component (A) may be selected from emulsifiers generally usable in cosmetics, etc., but lipophilic surfactants in which the fatty acids constituting the ester are unsaturated are particularly preferred. Examples of unsaturated fatty acids include oleic acid, erucic acid, linoleic acid, and ricinoleic acid, while examples of the hydrophilic portion of surfactants include sucrose, glycerin, sorbitan, and oxyethylene. Among these, sucrose oleate and sucrose erucate are preferred. Furthermore, from the viewpoints of usability, stability, and viscosity of the emulsion composition, surfactants in which the fatty acids constituting the ester are saturated fatty acids such as palmitic acid and stearic acid may also be used in combination. Among these, sucrose palmitate and sucrose stearate are preferred. Furthermore, from the viewpoint of usability, polyglycerol fatty acid esters, particularly condensed pentaglycerin ricinoleate, are preferred. The term "emulsifier" generally refers to a substance capable of emulsifying water and oil. For example, even if a substance is referred to as a surfactant, it can be used as an emulsifier as long as it has such functionality.

[0033] Component (A) may be an emulsifier, and may be used alone or in combination of two or more types.

[0034] The content of component (A) is dependent on the amounts of components (B) to (D) and other raw materials, and also varies depending on the type of emulsifier used, but typically, for example, it is preferably 0.1% by mass or more and 30% by mass or less of the total amount of the composition, and more preferably 0.5% by mass or more and 5.0% by mass or less. If the content is outside the above range, it may be difficult to form a stable emulsion composition.

[0035] The oil of component (B) may be any oil generally usable in cosmetics and is not particularly limited, but from the viewpoint of preparing a high internal phase W / O emulsion composition, it is preferable to use an oil that becomes liquid at the preparation temperature (e.g., 80°C).Furthermore, from the viewpoint of preparing an emulsified liquid cosmetic that has low viscosity and is easy to apply to the skin, it is preferable to use an oil that becomes liquid at room temperature (25°C).

[0036] Specifically, for example, it is an ester oil formed by esterifying fatty acids and alcohols. Examples of ester oils include cetyl 2-ethylhexanoate, isononyl isononanoate, isopropyl myristate, glyceryl tri-2-ethylhexanoate, 2-octyldodecyl myristate, 2-ethylhexyl palmitate, 2-octyldodecyl oleate, neopentyl glycol di-2-ethylhexanoate, glyceryl triisostearate, diisostearyl malate, 2-ethylhexanoic acid diglyceride, and caprylic / capric triglyceride. From the viewpoint of low viscosity and stability, cetyl 2-ethylhexanoate, isononyl isononanoate, glyceryl tri-2-ethylhexanoate, and caprylic / capric triglyceride are preferred.

[0037] Also, for example, hydrocarbon-based non-ester oils are used. Examples of non-ester oils include mineral oil (liquid paraffin), squalane, squalene, ceresin, etc. From the viewpoints of low viscosity and stability, mineral oil, squalane, etc. are preferred.

[0038] Another example is silicone-based silicone oil. Examples of silicone oil include diphenylsiloxytrimethicone, dimethicone (dimethylpolysiloxane), phenyltrimethicone, cyclopentasiloxane, etc. From the viewpoints of makeup compatibility and compatibility with other oil phase components when two or more types of oils are used, diphenylsiloxytrimethicone, cyclopentanesiloxane, etc. are preferred.

[0039] Another example is vegetable oil. Examples of vegetable oils include jojoba oil, olive oil, macadamia nut oil, camellia oil, avocado oil, rosehip oil, kukui nut oil, hazelnut oil, meadowfoam oil, etc. From the viewpoint of stability, macadamia nut oil, meadowfoam oil, etc. are preferred.

[0040] As the oil of component (B), one of the above oils may be used alone, or two or more of them may be used in combination.

[0041] As the oil of component (B), an oil other than those that become liquid at the temperature at which the high internal phase W / O emulsion composition is prepared (e.g., 80°C) or those that become liquid at room temperature (25°C), i.e., an oil with a higher melting point (hereinafter referred to as "other oil"), may be used in combination as appropriate. As the other oil, an emulsifier that can generally be used in cosmetics and the like may be appropriately selected and used. From the viewpoint of adjusting the feel of use of the cosmetic, for example, semi-solid oils such as cholesteryl hydroxystearate, dimer dilinoleate (phytosteryl / isostearyl / cetyl / stearyl / behenyl), di(octyldodecyl / phytosteryl / behenyl) lauroyl glutamate, and solid oils such as batyl stearate, behenyl alcohol, beeswax, and cholesterol may be used.

[0042] The other oils mentioned above may be used alone as the oil of component (B), or two or more types may be used in combination.

[0043] However, from the viewpoint of using a liquid emulsion at the preparation temperature of the emulsion composition (e.g., 80°C), or from the viewpoint of preparing an emulsion liquid cosmetic that has low viscosity and is easy to apply to the skin, the content of the above-mentioned other oils in the total amount of oil in component (B) is preferably more than 0% by mass and not more than 50% by mass, more preferably more than 0% by mass and not more than 25% by mass, and even more preferably more than 0% by mass and not more than 10% by mass. In some cases, it is most preferable that they are not contained.

[0044] The content of component (B) (the total amount when the above-mentioned other oils are included or when two or more types of oils are included) depends on the amounts of components (A), (C), and (D) and the amounts of other ingredients, and also varies depending on the type of oil used, but is typically, for example, preferably 0.1% by mass to 30% by mass of the total composition, and more preferably 5% by mass to 25% by mass. If the content exceeds this range, it may be difficult to maintain the proportion of the dispersed phase consisting of the aqueous phase. If the content is below this range, it may be difficult to maintain a W / O type emulsion state.

[0045] The water of component (C) is not particularly limited, and may be any water generally usable for cosmetics, such as purified water, distilled water, ion-exchanged water, RO water, or sterilized water.

[0046] The content of component (C) varies depending on the amounts of components (A), (B), and (D) and the amount of other raw materials, but is typically, for example, preferably 20% by mass to 99% by mass, more preferably 30% by mass to 95% by mass, and particularly preferably 30% by mass to 90% by mass. If the content is less than this range, it may be difficult to maintain the proportion of the dispersed phase consisting of the aqueous phase. If the content exceeds this range, it may be difficult to maintain a W / O type emulsion.

[0047] The content of the readily crystallizable water-soluble active ingredient (component (D)) varies depending on the amounts of components (A) to (C) and the relationship with the amounts of other raw materials, but typically, for example, the content of the readily crystallizable water-soluble active ingredient in the total amount of the composition, calculated as dry solids, is preferably 0.2% by mass to 10.0% by mass, more preferably 0.5% by mass to 5.0% by mass, and particularly preferably 1.0% by mass to 4.0% by mass. If the content is below this range, it may be difficult to achieve the effects of incorporating the active ingredient. On the other hand, if the content exceeds this range, it may be difficult to maintain a stable emulsified state of the emulsion composition.

[0048] The cosmetic composition of the present invention may contain an oil gelling agent in order to further stabilize the emulsified state.

[0049] The oil gelling agent is not particularly limited and may be appropriately selected from oil gelling agents generally usable in cosmetics, etc. Examples include esters of polysaccharides and fatty acids such as dextrin palmitate, dextrin myristate, dextrin (palmitate / ethylhexanoate), and inulin stearate, glycerin fatty acid esters such as glyceryl (behenate / eicosadioate) and glyceryl behenate, higher alcohols such as batyl alcohol and behenyl alcohol, and organically modified clay minerals. Among these, it is preferable to use dextrin fatty acid esters, glycerin fatty acid esters, etc., and more specifically, it is preferable to use dextrin palmitate, dextrin myristate, glyceryl (behenate / eicosadioate), glyceryl behenate, etc.

[0050] The oil gelling agent may be used alone or in combination of two or more kinds.

[0051] The content of the oil gelling agent depends on the amounts of components (A) to (D) and other ingredients, and varies depending on the type of oil gelling agent used. However, typically, a content of approximately 0.05% by mass or more of the total composition can contribute to the formation of a stable emulsion composition. The content is preferably 0.1% by mass or more, more preferably 0.1% to 10% by mass, and even more preferably 0.1% to 5% by mass. If the content is less than the above range, the effect of stabilizing the emulsion state of the composition is poor. Furthermore, even if the content exceeds the above range, the effect of stabilizing the emulsion state is poor depending on the content, and may actually hinder the formation of a stable emulsion composition.

[0052] In addition to the above-mentioned components, the cosmetic composition according to the present invention may optionally and appropriately contain other components that are generally contained in cosmetics, such as alcohols, organic acids, salts, preservatives, fragrances, colorants, antibacterial agents, plant extracts, etc. A thickener may also be added to increase the viscosity of the composition.

[0053] As alcohols, from the viewpoint of providing a moist feeling to the skin and improving the feeling in use, for example, sugar alcohols such as sorbitol, xylitol, and maltitol, and trihydric or higher polyhydric alcohols such as glycerin and diglycerin may be appropriately blended. Furthermore, from the viewpoint of preservative power, for example, dihydric alcohols such as dipropylene glycol, 1,3-butylene glycol, 1,2-pentylene glycol, and 1,2-hexylene glycol, and monohydric alcohols such as ethanol, propanol, isopropanol, butanol, and phenoxyethanol may be appropriately blended.

[0054] In addition, from the viewpoint of adjusting the feel of the cosmetic when used, aqueous thickeners such as xanthan gum, hydroxyethyl cellulose, carboxymethyl cellulose, silica (Al / Mg), carboxyvinyl polymer, and acrylic acid / alkyl methacrylate polymer may be appropriately blended.

[0055] In a preferred embodiment of the present invention, the other ingredients may further include a microbial fermentation product. The amino acids and other components contained in the microbial fermentation product provide moisturizing and other benefits to the skin. Examples of the microbial fermentation product include cultures obtained by fermenting ingredients commonly incorporated into cosmetics and the like with lactic acid bacteria (including bifidobacteria) or yeast, culture supernatants, and extracts obtained by extracting the cultures and / or culture supernatants with water or aqueous alcohol. Examples of such fermented milk products include, but are not limited to, a lactic acid bacteria / milk fermented liquid as described in Japanese Patent Publication No. 02-040643, a lactic acid bacteria / milk fermented liquid as described in Japanese Patent No. 4512265, a Lactobacillus / Aloe vera fermented liquid as described in Japanese Patent No. 3795011, a soy milk / Bifidobacteria fermented liquid as described in Japanese Patent No. 3184114, a culture obtained by fermenting a lactic acid bacteria culture in a milk component-containing medium with Kluyveromyces maxianus as described in Japanese Patent Publication No. 2017-212894, and a culture obtained by fermenting a lactic acid bacteria culture in a milk component-containing medium with Wickerhamomyces pijeperi as described in WO2016 / 117489.

[0056] The content of the microbial fermentation product is related to the amounts of components (A) to (D) and other raw materials, and also varies depending on the type of microbial fermentation product used and the purpose of incorporation, but typically, for example, the content of the microbial fermentation product is preferably 0.001% by mass or more and 0.4% by mass or less, and more preferably 0.01% by mass or more and 0.2% by mass or less, calculated as dry solids content of the microbial fermentation product relative to the total amount of the composition. If the content is less than this range, it becomes difficult to obtain the effects of incorporating the microbial fermentation product. If the content exceeds this range, it becomes difficult to maintain a stable emulsified state of the emulsion composition.

[0057] The cosmetic composition of the present invention can be generally prepared by a method well known to those skilled in the art. The cosmetic composition of the present invention is prepared by mixing or dispersing ingredients that are primarily oil-based (component (B)) and highly soluble or dispersible in oil to prepare a raw oil phase (hereinafter sometimes referred to as the "raw oil phase"). The cosmetic composition of the present invention is then mixed or dispersed with ingredients primarily water-based (component (C)) and highly soluble or dispersible in water to prepare a raw aqueous phase (hereinafter sometimes referred to as the "raw aqueous phase"). If necessary, the aqueous phase is gradually added to the raw oil phase at an appropriate temperature, e.g., room temperature to 80.0°C, while dispersing the mixture using a stirring mixer or the like. Once an emulsion is formed, the mixture may be cooled to room temperature or a stirring / cooling process may be employed, in which stirring is continued while gradually lowering the temperature. Since the oil gelling agents described above often have an affinity for oil, it is preferable to mix or disperse them in the raw oil phase during preparation. Meanwhile, the readily crystallizable water-soluble active ingredient of component (D) is preferably mixed or dispersed in the raw aqueous phase.

[0058] The cosmetic composition according to the present invention may be used as a cosmetic product as it is, or may be used as a cosmetic ingredient and incorporated into the cosmetic production process. Specifically, the cosmetic composition according to the present invention is suitable for use in the form of a cosmetic product such as a milky lotion, cream, cleanser, massage lotion, sunscreen, makeup base, cream foundation, or as an ingredient thereof. The term "cosmetics" as used herein includes pharmaceuticals, quasi-drugs, and cosmetics as defined in the Act on the Assurance of Quality, Efficacy, and Safety of Pharmaceuticals, Medical Devices, etc. [Example]

[0059] The present invention will be explained in more detail below with reference to examples, but these examples do not limit the scope of the present invention.

[0060] [Test Example 1] Various compositions containing magnesium ascorbyl phosphate, a vitamin C derivative, were prepared according to the formulations shown in Table 1. Hereinafter, magnesium ascorbyl phosphate may be abbreviated as "VC-PMG."

[0061] Preparation Example 1-1: W / O type emulsion composition (containing 3% by mass of magnesium ascorbyl phosphate) in which the ratio of the dispersed phase consisting of an aqueous phase to the continuous phase consisting of an oil phase is 85:15 Preparation Example 1-2: O / W emulsion composition with a ratio of dispersed phase consisting of an oil phase to continuous phase consisting of an aqueous phase of 13.9:86.1 (containing 3% by mass of magnesium ascorbyl phosphate) Preparation Example 1-3: Aqueous composition consisting only of an aqueous phase containing water-soluble components (containing 3% by mass of magnesium ascorbyl phosphate)

[0062] Specifically, for Preparation Examples 1-1 and 1-2, the raw materials constituting the oil and aqueous phases were first weighed out according to the formulations shown in Table 1, and then mixed and dissolved at 70-80°C to prepare the raw oil and aqueous phases separately. Next, in the case of Preparation Example 1-1, the raw aqueous phase was gradually added to the raw oil phase, or in the case of Preparation Example 1-2, the raw oil and aqueous phases were gradually added to the raw aqueous phase. The raw oil and aqueous phases were then mixed at 70-80°C using a Disper Mixer (product name "TK Robomix" (stirring blade φ40 mm), manufactured by Primix Corporation) with the impeller rotation speed set to 2500 rpm. The mixture was then stirred and cooled to 35°C to prepare various emulsion compositions (Preparation Examples 1-1 and 1-2). For Preparation Example 1-3, among the water-soluble raw materials shown in Table 1, 1,2-pentanediol and methylparaben were mixed and dissolved at 70 to 80°C, and then added to the remaining raw materials that had been mixed and dissolved at room temperature to prepare an aqueous composition.

[0063] The emulsion type of Preparation Examples 1-1 and 1-2 was determined by passing a current through the bulk. That is, a tester ("SanwaYX-361TR", Sanwa Electric Instruments Co., Ltd.) was used, and when the tester terminal was brought into contact with the preparation, if a current was passed through it was determined to be an O / W type, and if a current was not passed through it was determined to be a W / O type.

[0064] [Table 1]

[0065] The obtained preparation was filled into a screw-cap bottle and stored at 5°C, 40°C, or 50°C for 3 months, after which the formulation was evaluated by the following confirmation method.

[0066] (Confirmation of crystal formation) The crystals are optically anisotropic due to their regular structure, and a bright image is observed under a polarizing microscope. Therefore, the preparations were observed under a polarizing microscope after storage at each temperature to evaluate the state of crystal formation. Figure 1 shows an example of a polarizing microscope photograph.

[0067] (Quantitative analysis by HPLC) Crystal formation during storage was thought to be primarily due to magnesium ascorbyl phosphate (VC-PMG). Therefore, the residual percentage of VC-PMG in a dissolved or dispersed state without crystallization was investigated. Specifically, 0.2 g of the preparation was placed in a microtube, 150 μL of 1,2-pentanediol was added, and the mixture was mixed using a vortex mixer. The mixture was then diluted 5-fold (w / w) with purified water and centrifuged (Hitachi CF-16RN, 15,000 rpm, 10 minutes). The supernatant was filtered through a 0.22 μm filter. The filtrate was further diluted 20-fold (v / v) with purified water and subjected to HPLC analysis under the following analytical conditions for quantitative analysis of VC-PMG. The residual percentage of VC-PMG relative to the formulation amount was calculated using the following formula (1):

[0068] VC-PMG residual rate (%) = {quantitative value by HPLC / amount} × 100 (1)

[0069] [HPLC analysis conditions] System: UHPLC Ultimate 3000 (Thermo Fisher Scientific) Column: Kinetex 2.6um EVO C18 (150x4.6mm) Mobile phase: 20 mM phosphate buffer (pH 2.05) Flow rate: 0.7mL / min Detection wavelength: UV238nm

[0070] The results of the survival rate of VC-PMG are shown in Table 2.

[0071] [Table 2]

[0072] As a result, in Preparation Example 1-2, which is an O / W type emulsion composition, and Preparation Example 1-3, which is an aqueous composition, crystals precipitated at the bottom of the container after storage at 40°C and 50°C (not shown in the figure), and heterogeneity was significant, but in Preparation Example 1-1, which is a high internal phase W / O type emulsion composition, crystallization was low and crystallization was suppressed.

[0073] On the other hand, according to the results of investigating the residual rate of VC-PMG by HPLC analysis, as shown in Table 2, in Preparation Example 1-1, which is a high internal phase W / O type emulsion composition, more than 96% was detected in a dissolved or dispersed state even under storage conditions of 50°C, whereas in Preparation Example 1-2, which is an O / W type emulsion composition, and Preparation Example 1-3, which is an aqueous composition, the residual rate decreased to approximately 80% under storage conditions of 40°C, and further, under storage conditions of 50°C, the residual rate in Preparation Example 1-2 was approximately 60%, and in Preparation Example 1-3 the residual rate was approximately 70%.

[0074] From the above, it was revealed that a high internal phase W / O type emulsion composition is an effective dosage form for inhibiting the crystallization of magnesium ascorbyl phosphate (VC-PMG), a vitamin C derivative.

[0075] [Test Example 2] Various W / O emulsion compositions containing magnesium ascorbyl phosphate (VC-PMG), a vitamin C derivative, were prepared according to the formulations shown in Table 3 and evaluated for formulation. The preparation method was the same as in Preparation Example 1-1 in Test Example 1, and the residual rate of VC-PMG after 3 months of storage at 50°C was measured. As a result, the residual rate of Preparation Example 2-1 was 95%, that of Preparation Example 2-2 was 94.8%, that of Preparation Example 2-3 was 91.9%, and that of Preparation Example 2-4 was 74.5%. The results are shown in Figure 2.

[0076] [Table 3]

[0077] As a result, as shown in FIG. 2, when the internal phase ratio (aqueous phase ratio) of the W / O emulsion composition was below 70 mass %, the residual rate of VC-PMG significantly decreased.

[0078] [Test Example 3] Various W / O type emulsion compositions containing magnesium ascorbyl phosphate (VC-PMG), a vitamin C derivative, were prepared according to the formulations shown in Table 4 and evaluated as pharmaceuticals. The preparation and evaluation methods were the same as those in Preparation Example 1-1 in Test Example 1. Figure 3 shows a polarizing microscope photograph as an example of the results, and Table 5 shows the results of the residual rate of VC-PMG.

[0079] [Table 4]

[0080] [Table 5]

[0081] As a result, in Preparation Example 3-2, an O / W emulsion composition, crystals precipitated at the bottom of the container after storage at 50°C (not shown in the figure), and heterogeneity was significant. On the other hand, in Preparation Example 3-1, a high internal phase W / O composition, crystallization was suppressed.

[0082] On the other hand, according to the results of investigating the residual rate of VC-PMG by HPLC analysis, as shown in Table 5, in Preparation Example 3-1, which is a high internal phase W / O type emulsion composition, nearly 90% was detected in a dissolved or dispersed state even under storage conditions of 50°C, whereas in Preparation Example 3-2, which is an O / W type emulsion composition, the residual rate decreased to approximately 70% under storage conditions of 50°C.

[0083] From the above, it has become clear that a high internal phase W / O type emulsion composition prepared using a glycerin fatty acid ester as an emulsifier to be contained in the oil phase is an effective formulation for inhibiting the crystallization of magnesium ascorbyl phosphate (VC-PMG), a vitamin C derivative, similar to the high internal phase W / O type emulsion composition prepared using a sucrose fatty acid ester as an emulsifier to be contained in the oil phase shown in Test Examples 1 and 2.

[0084] [Test Example 4] Various W / O emulsion compositions containing magnesium ascorbyl phosphate (VC-PMG), a vitamin C derivative, were prepared according to the formulations shown in Table 6. The resulting preparations were filled into screw-cap bottles and stored at 40°C for 9 months, after which pharmaceutical evaluation was performed using quantitative analysis by HPLC. The preparation and evaluation methods were the same as those in Preparation Example 1-1 in Test Example 1. Table 7 shows the results of the residual rate of VC-PMG.

[0085] [Table 6]

[0086] [Table 7]

[0087] As a result, it was revealed that a high internal phase W / O type emulsion composition is an effective formulation for inhibiting crystallization, even when the concentration of magnesium ascorbyl phosphate (VC-PMG) is 0.5, 1.0, or 5.0%.

Claims

[Claim 1] A cosmetic composition comprising (A) an emulsifier, (B) oil, (C) water, and (D) a readily crystallizable water-soluble active ingredient, characterized in that the cosmetic composition is a high internal phase W / O type emulsion composition in which the proportion of the aqueous phase is 70 mass% or more, wherein the emulsifier (A) is sucrose pentaerucate and / or condensed pentaglyceryl ricinoleate.

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