Emulsion composition

Abstract

The object of the present invention is to provide an emulsifying composition comprising pyrrolidone carboxylic acid and / or a salt thereof, which has excellent emulsifying stability. [Solution] In an emulsified composition containing pyrrolidone carboxylic acid and / or a salt thereof, the pylori By incorporating ufenamate together with donic acid and / or its salt, excellent emulsification stability is achieved.

Description

Technical Field

[0001] The present invention relates to an emulsion composition containing pyrrolidone carboxylic acid and / or its salt, and having excellent stability in properties.

Background Art

[0002] Emulsion compositions can blend aqueous components and oily components, can be adapted to various pharmaceutical formulations, and also have an excellent feel when applied to the skin. For this reason, emulsion compositions are widely used in the fields of topical pharmaceuticals and cosmetics.

[0003] Sodium pyrrolidone carboxylate is a component blended as a humectant in topical compositions and is also blended in emulsion compositions.

[0004] For example, Patent Document 1 describes that in an emulsion composition containing α-monoalkyl glyceryl ether, waxes, and a predetermined silicone oil, a humectant selected from the group consisting of glycerin, fructose, trimethylglycine, sodium lactate, and sodium pyrrolidone carboxylate may be blended. Patent Document 2 describes that in an emulsion composition containing 0.1 to 10% by mass of a water-soluble polymer obtained by mixing a predetermined agar and xanthan gum at a predetermined mass ratio and 30% by mass or more of water, one or more humectants selected from hyaluronic acid or its salt, pyrrolidone carboxylic acid or its salt, glycerin, diglycerin, and polyglycerin may be blended. Patent Document 3 describes that a topical skin composition having a predetermined pH containing ascorbyl glucoside, 2-amino-2-hydroxymethyl-1,3-propanediol, and ethylenediaminetetraacetic acid or its salt can be prepared as an emulsion composition, and pyrrolidone carboxylic acid or its salt may be blended.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Although Patent Documents 1 to 3 describe that pyrrolidone carboxylic acid or its salts may be included in the emulsified compositions, the actual stability of the properties of the emulsified compositions when pyrrolidone carboxylic acid or its salts are included has not been studied. The present inventors prepared an emulsified composition containing pyrrolidone carboxylic acid or its salts and encountered the problem of separation occurring after storage and unstable properties.

[0007] Therefore, the present invention aims to provide an emulsifying composition comprising pyrrolidone carboxylic acid or a salt thereof, which has excellent emulsifying stability. [Means for solving the problem]

[0008] The inventors of the present invention conducted thorough research on emulsifying compositions containing pyrrolidone carboxylic acid or its salts, and unexpectedly discovered that incorporating ufenamate, whose emulsifying stabilizing effect had not been previously known, provided excellent emulsifying stability. The present invention was completed by further research based on this finding.

[0009] In other words, the present invention provides inventions in the following embodiments. Item 1. An emulsified composition containing pyrrolidone carboxylic acid and / or a salt thereof, and ufenamate. Item 2. The emulsifying composition according to Item 1, comprising 0.001 to 10% by weight in total of the pyrrolidone carboxylic acid and / or its salt. Item 3. The emulsified composition according to item 1 or 2, wherein the ufenamate is contained in an amount of 1.5 parts by weight or more per 1 part by weight of the total amount of the pyrrolidone carboxylic acid and / or its salt. Item 4. An emulsification stabilization method comprising blending ufenamate together with the pyrrolidone carboxylic acid and / or a salt thereof in an emulsified composition containing the pyrrolidone carboxylic acid and / or a salt thereof. [Effects of the Invention]

[0010] According to the present invention, an emulsion composition containing pyrrolidone carboxylic acid or a salt thereof can be provided with excellent emulsion stability. [Modes for carrying out the invention]

[0011] 1. Emulsified composition The emulsifying composition of the present invention is characterized by containing pyrrolidone carboxylic acid and / or a salt thereof, and ufenamate. The emulsifying composition of the present invention will be described in detail below.

[0012] Pyrrolidone carboxylic acid and / or salts thereof The pyrrolidone carboxylic acid and / or its salt contained in the emulsifying composition of the present invention is a known component as a humectant. Pyrrolidone carboxylic acid and / or its salt destabilizes the properties of the emulsifying composition after storage, but the emulsifying composition of the present invention exhibits excellent emulsification stability.

[0013] Pyrrolidone carboxylic acid is a component also known as pyroglutamic acid or pyrudolic acid. The stereostructure of pyrrolidone carboxylic acid is not particularly limited and may be D-pyrrolidone carboxylic acid, L-pyrrolidone carboxylic acid, or DL-pyrrolidone carboxylic acid.

[0014] The salts of pyrrolidone carboxylic acid are not particularly limited as long as they are pharmaceutically or cosmetically acceptable, but examples include alkali metal salts such as sodium salts, potassium salts, and lithium salts; alkaline earth metal salts such as calcium salts and magnesium salts; ammonium salts, alkanolamine salts, etc. These pyrrolidone carboxylic acid salts may be used individually or in combination of multiple types. Among these pyrrolidone carboxylic acids, alkali metal salts are preferred, and sodium salts are more preferred.

[0015] The emulsifying composition of the present invention exhibits excellent emulsifying stability after storage, and therefore, effective emulsifying stability can be obtained even when a larger amount of electrolytes that tend to cause aggregation of emulsifying particles are present. From this viewpoint, it is even more preferable that the emulsifying composition of the present invention contains a salt of pyrrolidone carboxylic acid, which generates more electrolytes through complete ionization, among pyrrolidone carboxylic acid and salts of pyrrolidone carboxylic acid.

[0016] The content of pyrrolidone carboxylic acid and / or its salt in the emulsified composition of the present invention is not particularly limited and can be appropriately determined depending on the desired moisturizing properties, etc., but for example, the total amount of pyrrolidone carboxylic acid and / or its salt can be 0.001 to 10% by weight. From the viewpoint of obtaining even more favorable emulsification stability, a preferred example of the content of pyrrolidone carboxylic acid and / or its salt is 0.001 to 5% by weight. Furthermore, since the emulsified composition of the present invention has excellent emulsification stability after storage, effective emulsification stability can be obtained even if a relatively large amount of pyrrolidone carboxylic acid and / or its salt is included. From this viewpoint, a preferred example of the content of pyrrolidone carboxylic acid and / or its salt in the emulsified composition of the present invention is 0.1 to 10% by weight, preferably 1 to 10% by weight, and more preferably 2 to 10% by weight.

[0017] Ufenamart The bufexamac contained in the emulsified composition of the present invention is also called butyl flufenamate and is a component known as a water-insoluble non-steroidal anti-inflammatory drug. Although the emulsified composition containing pyrrolidone carboxylic acid and / or its salt has unstable properties after storage, the emulsified composition of the present invention exhibits excellent emulsion stability by incorporating bufexamac.

[0018] The content of bufexamac in the emulsified composition of the present invention is not particularly limited and is appropriately set according to the emulsion stability to be imparted. For example, it may be 1 to 20% by weight, preferably 2 to 10% by weight, and more preferably 3 to 7% by weight.

[0019] In the emulsified composition of the present invention, the ratio of bufexamac to pyrrolidone carboxylic acid and / or its salt is determined according to the respective contents of the above components. From the viewpoint of obtaining even more excellent emulsion stability, for example, the content of bufexamac per 1 part by weight of the total amount of pyrrolidone carboxylic acid and / or its salt is, for example, 1.5 parts by weight or more, preferably 1.8 parts by weight or more, and more preferably 2 parts by weight or more. The upper limit of the content range of bufexamac per 1 part by weight of the total amount of pyrrolidone carboxylic acid and / or its salt is not particularly limited, but examples include 40 parts by weight or less, preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and still more preferably 5 parts by weight or less.

[0020] oil The emulsified composition of the present invention contains an oil component as a base component of the oil phase. The oil component is not particularly limited as long as it is pharmaceutically or cosmetically acceptable, and examples include liquid oils, solid oils, higher alcohols, and the like. These oil components may be used alone or in combination of two or more.

[0021] The content of the oil component in the emulsified composition of the present invention may be appropriately set according to the emulsion type, form, use, etc. of the emulsified composition. For example, it may be 2 to 60% by weight, preferably 4 to 30% by weight, more preferably 4 to 15% by weight, and still more preferably 6 to 8% by weight.

[0022] In the emulsified composition of the present invention, it is preferable to include liquid oil among the above-mentioned oil components. Liquid oil is an oil that maintains a liquid form at 25°C. The liquid oil can be any oil that is commonly used in cosmetics and topical pharmaceuticals, and examples include: fatty acids such as oleic acid and isostearic acid; ester oils such as cetyl ethylhexanoate, ethylhexyl palmitate, octyldodecyl myristate, isopropyl myristate, neopentyl glycol diethylhexanoate, glyceryl tri-2-ethylhexanoate, octyldodecyl oleate, isopropyl myristate, glyceryl triisostearate, and glyceryl divalamethoxycinnamate-monoethylhexanoate; silicone oils such as dimethylpolysiloxane, methylhydrodienepolysiloxane, methylphenylpolysiloxane, and octamethylcyclotetrasiloxane; and liquid hydrocarbon oils such as liquid paraffin, squalene, and squalane.

[0023] These liquid oils may be used individually or in combination of two or more types.

[0024] Among these liquid oils, ester oils, silicone oils, and liquid hydrocarbon oils are preferred, and octyldodecyl myristate, isopropyl myristate, dimethylpolysiloxane, and liquid paraffin are more preferred. Furthermore, among these liquid oils, liquid hydrocarbon oils are preferred, and liquid paraffin is more preferred, from the viewpoint of obtaining even better emulsification stability.

[0025] When the emulsifying stabilizer of the present invention contains liquid oil, the amount is not particularly limited and can be appropriately set according to the emulsification type, form, and use of the emulsifying composition. For example, 0.5 to 30% by weight, preferably 1 to 20% by weight, more preferably 3 to 10% by weight, and even more preferably 5 to 8% by weight are given.

[0026] water The emulsifying composition of the present invention contains water as a base component of the aqueous phase. The water content in the emulsifying composition of the present invention can be appropriately set depending on the emulsification type, form, and application of the emulsifying composition, but for example, 30 to 95% by weight, preferably 30 to 90% by weight, more preferably 30 to 80% by weight, and even more preferably 30 to 75% by weight are examples.

[0027] Furthermore, the emulsifying composition of the present invention possesses excellent emulsifying stability that suppresses aqueous phase separation after storage. Therefore, even when it contains a large amount of water, which is inherently more prone to aqueous phase separation, it is possible to obtain excellent emulsifying stability. In view of these effects of the present invention, a preferred embodiment of the emulsifying composition of the present invention is an emulsifying composition with a relatively high water content. More specifically, preferred examples of the water content in the emulsifying composition of the present invention include, for example, 40 to 95% by weight, preferably 45 to 95% by weight, more preferably 50 to 95% by weight, even more preferably 55 to 95% by weight, and even more preferably 60 to 95% by weight.

[0028] surfactant The emulsifying composition of the present invention contains a surfactant as a component for emulsifying the oil phase and the aqueous phase. The surfactant is not particularly limited as long as it is pharmaceutically or cosmetically acceptable, but examples include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, etc.

[0029] From the viewpoint of obtaining even better emulsification stability, the HLB value of the surfactant can be, for example, 10 to 19, preferably 13 to 17.5, and more preferably 13.5 to 15.5. The HLB value is calculated according to the Kawakami method (HLB value = 7 + 11.7 log (sum of molecular weights of hydrophilic parts / sum of molecular weights of lipophilic parts)).

[0030] Among these surfactants, nonionic surfactants are preferred from the viewpoint of obtaining better emulsification stability.

[0031] Nonionic surfactants include, specifically, polyoxyethylene hydrogenated castor oils (e.g., PEG-40 hydrogenated castor oil, PEG-50 hydrogenated castor oil, PEG-60 hydrogenated castor oil, PEG-80 hydrogenated castor oil, PEG-100 hydrogenated castor oil); sorbitan fatty acid esters (e.g., sorbitan monooleate, sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan tri Diglycerol sorbitan tetra-2-ethylhexylate, diglycerol sorbitan tetra-2-ethylhexylate, etc.); Glycerin fatty acid esters (e.g., glyceryl monocottonseed oil fatty acid, glyceryl monoerucate, glyceryl sesquioleate, glyceryl monostearate (glyceryl stearate), glyceryl pyroglutamate α,α'-oleate, glyceryl monostearate malic acid, etc.); Propylene glycol fatty acid esters (e.g., propylene glycol monostearate, etc.) ); Glycerin alkyl ether; Steareth-2; Polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tetraoleate, etc.); Polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan pentaoleate, polyoxyethylene sorbitan monostearate, etc.); Polyoxyethylene glycerin fatty acid esters (e.g., polyoxyethylene glycerin monostearate, polyoxyethylene glycerin monoisostearate, polyoxyethylene glycerin triisostearate, etc.); Polyoxyethylene fatty acid esters (e.g., polyoxyethylene monooleate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monodioleate, ethylene glycol distearate, etc.);Examples include polyoxyethylene alkyl ethers (e.g., polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene 2-octyldodecyl ether, polyoxyethylene cholestanol ether, etc.); Pluronic® type ethers (e.g., Pluronic®, etc.); polyoxyethylene / polyoxypropylene alkyl ethers (e.g., polyoxyethylene / polyoxypropylene cetyl ether, polyoxyethylene / polyoxypropylene-2-decyltetradecyl ether, polyoxyethylene / polyoxypropylene monobutyl ether, polyoxyethylene / polyoxypropylene hydrogenated lanolin, polyoxyethylene / polyoxypropylene glycerin ether, etc.); and Steareth-21, etc.

[0032] These surfactants may be used individually or in combination of two or more.

[0033] Among these nonionic surfactants, from the viewpoint of obtaining better emulsification stability, polyoxyethylene hydrogenated castor oils, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene fatty acid esters are preferred, and more preferably PEG-60 hydrogenated castor oil, polyoxyethylene sorbitan monostearate, and polyoxyethylene monostearate are preferred. Furthermore, among these nonionic surfactants, from the viewpoint of obtaining even better emulsification stability, polyoxyethylene sorbitan fatty acid esters are preferred, and more preferably polyoxyethylene sorbitan monostearate is preferred.

[0034] In the emulsifying composition of the present invention, the surfactant content can be appropriately set depending on the type of surfactant used, but for example, it can be 0.5 to 7% by weight, preferably 1 to 5% by weight, more preferably 2 to 5% by weight, and even more preferably 3 to 5% by weight.

[0035] Other ingredients In addition to the components described above, the emulsifying composition of the present invention may contain other commonly used additives as needed. Examples of such additives include polyhydric alcohols, thickeners, pH adjusters, buffers, solubilizers, chelating agents, preservatives, antioxidants, stabilizers, fragrances, colorants, and the like.

[0036] The polyhydric alcohol is not particularly limited as long as it is pharmaceutically or cosmetically acceptable, but examples include dihydric alcohols such as propylene glycol, 1,3-butylene glycol, ethylene glycol, isoprene glycol, diethylene glycol, and dipropylene glycol; trihydric alcohols such as glycerin; and polyethylene glycols such as macrogol 4000 and macrogol 6000. These polyhydric alcohols may be used individually or in combination of two or more. Among these polyhydric alcohols, from the viewpoint of obtaining better emulsification stability, dihydric and trihydric alcohols are preferred, and 1,3-butylene glycol and glycerin are more preferred.

[0037] In the emulsified composition of the present invention, when a polyhydric alcohol is included, the amount can be appropriately set depending on the type of polyhydric alcohol used, but for example, 1 to 20% by weight, preferably 5 to 18% by weight, and more preferably 10 to 16% by weight is used.

[0038] The thickening agent is not particularly limited as long as it is pharmaceutically or cosmetically acceptable, but examples include carboxyvinyl polymer, hypromellose, polyvinylpyrrolidone, sodium alginate, ethylcellulose, sodium carboxymethylcellulose, xanthan gum, and carrageenan. Among these thickening agents, xanthan gum is preferred from the viewpoint of obtaining better emulsion stability. Furthermore, among these thickening agents, carboxyvinyl polymer undergoes an extreme decrease in viscosity in the presence of pyrrolidone carboxylic acid and / or its salts, and when incorporated into a normal emulsion composition containing pyrrolidone carboxylic acid and / or its salts, it leads to a significant decrease in storage stability. However, the emulsion composition of the present invention has excellent emulsion stability after storage, so even if carboxyvinyl polymer is included, effective emulsion stability can be obtained. In view of these effects of the present invention, it is preferable that the emulsion composition of the present invention contains at least carboxyvinyl polymer as a thickening agent.

[0039] When a thickener is included in the emulsified composition of the present invention, its content can be appropriately set depending on the type of thickener used, etc., but from the viewpoint of obtaining better emulsification stability, for example, 0.1 to 2% by weight, preferably 0.1 to 1.8% by weight, more preferably 0.2 to 1.5% by weight, even more preferably 0.3 to 1% by weight, and even more preferably 0.3 to 0.6% by weight can be cited. Furthermore, when a carboxyvinyl polymer is included in the emulsified composition of the present invention, the content of the carboxyvinyl polymer can be, for example, 0.1 to 1% by weight, preferably 0.3 to 0.5% by weight, and more preferably 0.35 to 0.45% by weight can be cited. Furthermore, the ratio of carboxyvinyl polymer to pyrrolidone carboxylic acid and / or its salt can be determined according to the respective contents of each of the above components, but for example, the content of carboxyvinyl polymer per 1 part by weight of the total amount of pyrrolidone carboxylic acid and / or its salt can be, for example, 0.01 to 0.5 parts by weight, preferably 0.03 to 0.3 parts by weight, and more preferably 0.06 to 0.2 parts by weight can be cited.

[0040] Furthermore, in addition to the components described above, the emulsified composition of the present invention may optionally contain pharmaceutically or cosmetically active ingredients that can exert physiological functions. Examples of such medicinal ingredients include steroids (dexamethasone, dexamethasone hydrochloride, dexamethasone acetate, hydrocortisone hydrochloride, prednisolone valerate, prednisolone acetate, etc.), antihistamines (diphenhydramine, diphenhydramine hydrochloride, chlorpheniramine maleate, etc.), local anesthetics (lidocaine, dibucaine, procaine, tetracaine, bupivacaine, mepivacaine, chloroprocaine, propalacaine, meprilcaine, or salts thereof), alkyl benzoates (e.g., ethyl aminobenzoate, diethylaminoethyl parabutylaminobenzoate hydrochloride), orthocaine, oxethazaine, oxypolyentoxydecane, belladonna extract, percaminate, tesitdecin, etc.), and anti-inflammatory agents (alopropyl alcohol). Examples of active ingredients include anthoin, salicylic acid, glycol salicylate, methyl salicylate, indomethacin, felbinac, diclofenac sodium, loxoprofen sodium, etc., antiseptics (benzalkonium chloride, decalinium chloride, benzethonium chloride, cetylpyridinium chloride, chlorhexidine hydrochloride, chlorhexidine gluconate, ammonia water, sulfadiazine, lactic acid, phenol, etc.), antipruritic agents (crotamiton, thianthol, etc.), skin protectants (collodion, castor oil, etc.), blood circulation promoting ingredients (nonyl vanillylamide, benzyl nicotinate, capsaicin, chili pepper extract, etc.), vitamins (vitamins A, B, C, D, E, etc.), and mucopolysaccharides (chondroitin sulfate sodium, glucosamine, hyaluronic acid, etc.). These active ingredients may be used individually or in combination of two or more. Furthermore, when these pharmacoactive ingredients are included in the emulsified composition of the present invention, their content may be appropriately determined according to the type of pharmacoactive ingredient used, the expected effect, etc.

[0041] Formulation and Use The emulsion type of the emulsified composition of the present invention may be either water-in-oil or oil-in-water. The emulsified composition of the present invention exhibits excellent emulsification stability that suppresses separation after storage, making it possible to provide excellent emulsification stability even with oil-in-water types, which inherently contain a large amount of water and are more prone to aqueous phase separation. In view of these effects of the present invention, the preferred emulsion type of the emulsified composition of the present invention is the oil-in-water type, which has a relatively high water content.

[0042] The emulsified composition of the present invention can be used as an external preparation such as cosmetics, quasi-drugs for external use, and pharmaceuticals for external use. The product form of the emulsified composition of the present invention is not particularly limited, but examples include creams, ointments, emulsions, gels, oils, lotions, liniments, and aerosols. Among these, creams, ointments, emulsions, and lotions are preferred, and creams, emulsions, and lotions are more preferred.

[0043] Manufacturing method The emulsified composition of the present invention can be manufactured according to known emulsifying formulation methods, depending on the type of emulsification. For example, a method for manufacturing the emulsified composition of the present invention involves separating the components to be contained into water-soluble components and oily components, preparing an aqueous phase containing the water-soluble components and an oily phase containing the oily components, and emulsifying these according to known methods.

[0044] 2. Emulsion stabilization method As described above, ufenamate exhibits excellent emulsion stability in emulsion compositions containing pyrrolidone carboxylic acid and / or its salts. Therefore, the present invention further provides an emulsion stabilization method comprising incorporating ufenamate together with pyrrolidone carboxylic acid and / or its salts in an emulsion composition containing pyrrolidone carboxylic acid and / or its salts.

[0045] In the emulsification stabilization method of the present invention, emulsification stabilization means suppressing the separation of the emulsified composition after storage. Separation means the separation of the aqueous phase and / or oil phase from the emulsified composition. A more preferred embodiment of emulsification stabilization is suppressing the separation of the aqueous phase from the emulsified composition after storage, and a more preferred embodiment is that the emulsified state of the emulsified composition is uniform after storage, that is, the state in which the droplets in the emulsion are uniformly dispersed in the dispersion medium is maintained.

[0046] In the emulsification stabilization method of the present invention, the types and amounts of each component used, the types and amounts of components incorporated into the emulsification composition, and the formulation form are the same as in the case of "1. Emulsification Composition" described above. [Examples]

[0047] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. It's not that.

[0048] Test example The emulsified compositions shown in Tables 1 and 2 were prepared. Specifically, component (B) was added to the mixture of components (I) and dissolved at 70-80°C to prepare the oil phase. Meanwhile, the mixture of components (II) was dissolved at 75-85°C, and a 50% by weight aqueous solution of component (A) was added to prepare the aqueous phase. The aqueous phase, heated to 70-80°C, was added to the oil phase, heated to 70-80°C, and emulsified by stirring with a homomixer, then cooled to 35°C. This produced the emulsified composition (emulsion; oil-in-water type).

[0049] Ten g of each obtained emulsified composition was filled into a 15 mL transparent plastic tube, sealed, and centrifuged at 3,000 rpm for 10 minutes. After centrifugation, each emulsified composition was visually observed, and its emulsification stability was evaluated based on the following criteria. The results are shown in Tables 1 and 2. --: Phase separation is clearly observed, and the degree of turbidity in the aqueous phase is low. -: Phase separation is clearly observed, and the degree of turbidity in the aqueous phase is high. +: No phase separation was observed; only a tendency towards creaming was observed. ++: No phase separation was observed, and only a slight tendency towards creaming was observed at the bottom tip of the tube. +++: No phase separation was observed, and the emulsification state was uniform. Creaming tendency refers to a non-uniform state of the emulsion, specifically, a state in which droplets in the generated emulsion float or settle due to the difference in specific gravity with the dispersion medium.

[0050] [Table 1]

[0051] [Table 2]

[0052] As is clear from Table 2, the emulsion state was stable in the emulsion composition without sodium pyrrolidone carboxylate (Reference Example), but the emulsion state became unstable in the emulsion composition containing sodium pyrrolidone carboxylate (Comparative Examples 1 and 2). In contrast, as is clear from Table 1, the emulsion state was stabilized by further adding ufenamate to the emulsion composition containing sodium pyrrolidone carboxylate (Examples 1 to 7). This improvement in emulsion stability was particularly significant in Examples 1, 4 to 7.

[0053] Prescription examples Emulsified compositions (oil-in-water type) were prepared according to the formulations shown in Tables 3 and 4. All of the emulsion compositions exhibited excellent emulsion stability.

[0054] [Table 3]

[0055] [Table 4]

Claims

1. An emulsifying composition containing 2 to 10% by weight of pyrrolidone carboxylic acid and / or its salt, ufenamate, and a nonionic surfactant.

2. The emulsifying composition according to claim 1, wherein the ufenamate is contained in an amount of 1.5 parts by weight or more per 1 part by weight of the total amount of the pyrrolidone carboxylic acid and / or its salt.

3. The emulsifying composition according to claim 1 or 2, wherein the content of the nonionic surfactant is 3 to 7% by weight.

4. A method for stabilizing an emulsion, comprising adding ufenamate together with the pyrrolidone carboxylic acid and / or its salt to an emulsion composition containing 2 to 10% by weight of pyrrolidone carboxylic acid and / or its salt and a nonionic surfactant.

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