External components

Abstract

To provide a composition for external use, in which a decrease in viscosity is suppressed although urea and a thickening agent are contained in the composition.SOLUTION: This composition for external use contains (A) urea, (B) a thickening agent, and (C) a solid hydrocarbon oil, and the composition suppresses a decrease in viscosity after storage at a high temperature. Preferably, component (B) is (meth)acrylate polymer, and component (C) is petrolatum.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a topical composition containing urea and a thickener, which is inhibited from losing viscosity. [Background technology]

[0002] Urea has the ability to retain moisture in the stratum corneum and also has a keratolytic effect, and therefore has been used as an active ingredient in external compositions such as skin cosmetics, pharmaceuticals, and quasi-drugs for the treatment of skin diseases such as atopic dermatitis, senile xerosis, and ichthyosis, as well as for the relief of dry skin, itching, chapped skin, and the like.

[0003] Generally, thickeners are used in topical compositions containing urea to improve usability, etc. However, when urea and a thickener are used together, depending on the type and amount, there is a known problem that the viscosity cannot be maintained and sufficient formulation stability cannot be achieved. As a formulation that solves this problem of reduced viscosity, Patent Document 1 discloses a transparent gel cosmetic that contains urea, a urea stabilizer consisting of a combination of a hydroxy acid and its salt, and a carboxyvinyl polymer, and that contains 0.65 to 2% by mass of the carboxyvinyl polymer based on the total amount of the cosmetic. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-190986 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the formulations described above are limited to a relatively high content of carboxyvinyl polymer and contain irritating hydroxy acids as urea stabilizers, which can make them unable to accommodate the increasingly diverse formulations of topical compositions. Therefore, there is a need to develop new formulation technologies that can suppress viscosity reduction in topical compositions containing urea and a thickener.

[0006] The present invention aims to provide a composition for external use that contains urea and a thickener but that is inhibited from losing viscosity. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that by incorporating a solid hydrocarbon into a topical composition containing urea and a thickener, an excellent effect of inhibiting viscosity reduction can be achieved. Based on this finding, further research was conducted and the present invention was completed.

[0008] That is, the present invention provides the following aspects. Item 1. A composition for external use containing (A) urea, (B) a thickener, and (C) a solid hydrocarbon oil. Item 2. The topical composition according to Item 1, wherein component (C) is petrolatum. Item 3. The topical composition according to Item 1, wherein the component (B) is a (meth)acrylic acid-based polymer. Item 4. The composition for external use according to any one of Items 1 to 3, wherein the content of the component (A) is 5 to 40 wt %. Item 5. The composition for external use according to any one of Items 1 to 4, wherein the content of component (C) is 0.01 to 20% by weight. Item 6. The composition for external use according to any one of Items 1 to 5, wherein the content of the component (C) per 1 weight of the component (A) is 0.01 to 1 part by weight. Item 7. The composition for external use according to Item 1, which is an emulsion composition. Item 8. A method for suppressing a decrease in viscosity of a topical composition containing (A) urea and (B) a thickener, comprising: A method for inhibiting a decrease in viscosity, comprising blending a solid hydrocarbon oil (C) with the topical composition together with the components (A) and (B). [Effects of the Invention]

[0009] The topical composition of the present invention exhibits an excellent effect of inhibiting a decrease in viscosity, even though it contains urea and a thickener. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. External composition The topical composition of the present invention is characterized by containing (A) urea (hereinafter also referred to as "component (A)"), (B) a thickener (hereinafter also referred to as "component (B)"), and (C) a solid hydrocarbon oil (hereinafter also referred to as "component (C)"). The topical composition of the present invention is described in detail below.

[0011] Component (A) The topical composition of the present invention contains urea as component (A). Urea is a known component that retains moisture in the keratinocyte through hydrogen bonding and has a keratolytic effect that removes unnecessary keratin through protein denaturation.

[0012] The urea used in the present invention is not particularly limited in terms of raw materials, production method, purification method, etc., and may be one produced by chemical synthesis or a commercially available product. Examples of commercially available urea include products manufactured or sold by Takasugi Pharmaceutical Co., Ltd., Showa Chemical Co., Ltd., Kanto Chemical Co., Ltd., etc.

[0013] The content of urea in the topical composition of the present invention may be appropriately determined depending on the desired efficacy, etc., and is not particularly limited, but may be, for example, 5 to 40% by weight. Because the topical composition of the present invention has an excellent viscosity reduction inhibitory effect, it can effectively inhibit viscosity reduction even when it contains a relatively large amount of urea, which would otherwise significantly reduce viscosity. In view of these effects of the present invention, suitable examples of the urea content in the topical composition of the present invention include preferably 10 to 40% by weight, more preferably 15 to 30% by weight, and even more preferably 20 to 25% by weight.

[0014] (B) Thickener The topical composition of the present invention contains a thickener as component (B). Thickeners may be any thickener commonly used in cosmetics, topical pharmaceuticals, etc. Suitable examples of thickeners used in the present invention include water-soluble thickeners. Examples of water-soluble thickeners include (meth)acrylic acid-based polymers, cellulose ether-based polymers, vinyl-based polymers, and polysaccharides.

[0015] Examples of (meth)acrylic acid polymers include carboxyvinyl polymers, (meth)acrylic acid alkyl copolymers, acrylic acid / alkyl methacrylate copolymers; (meth)acrylic acid / alkyl (meth)acrylate / (meth)acrylic acid alkyl ether copolymers such as acrylates / polyoxyethylene (20) methacrylate cetyl ether copolymer, acrylates / polyoxyethylene (20) methacrylate stearyl ether copolymer, and acrylates / polyoxyethylene (25) methacrylate behenyl ether copolymer; and acrylates / Examples of suitable (meth)acrylic acid / alkyl (meth)acrylate / polyoxyethylene itaconate alkyl ether copolymers include polyoxyethylene (20) itaconate cetyl ether copolymer and acrylate / polyoxyethylene (20) itaconate stearyl ether copolymer; (meth)acrylic acid / alkyl (meth)acrylate / polyoxyethylene (meth)acrylate alkyl ether crosspolymers such as acrylate / polyoxyethylene (20) methacrylate stearyl ether crosspolymer; and acrylate / vinyl neodecanoate crosspolymer. The number in parentheses indicates the number of moles of ethylene oxide added. These (meth)acrylic acid-based polymers may be used alone or in combination of two or more.

[0016] Examples of cellulose ether polymers include methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, etc. These cellulose ether polymers may be used alone or in combination of two or more.

[0017] Examples of vinyl polymers include polyvinyl alcohol, polyvinylpyrrolidone, etc. These vinyl polymers may be used alone or in combination of two or more.

[0018] Examples of polysaccharides include xanthan gum, guar gum, locust bean gum, carrageenan, dextran, alginic acid or a salt thereof, etc. These polysaccharides may be used alone or in combination of two or more.

[0019] In the topical composition of the present invention, component (B) may be one selected from (meth)acrylic acid-based polymers, cellulose ether-based polymers, vinyl-based polymers, and polysaccharides, or two or more may be used in combination.

[0020] Among these components (B), from the viewpoint of obtaining further improved viscosity reduction suppression properties, a (meth)acrylic acid-based polymer is preferred, and a carboxyvinyl polymer is more preferred.

[0021] Carboxyvinyl polymers are hydrophilic polymers whose main unit structure is acrylic acid. They are not particularly limited as long as they can dissolve in water and thicken the body. They may be partially crosslinked or may be copolymers containing other unit structures. Examples of carboxyvinyl polymers include those with an average molecular weight (mass-average molecular weight measured as a polystyrene equivalent using gel permeation chromatography (GPC)) of 300,000 to 5,000,000. Specific examples of carboxyvinyl polymers having such molecular weights include Carbopol 980 and Carbopol 981 (both Noveon Inc.), Hiviswako 103, Hiviswako 104, and Hiviswako 105 (both Wako Pure Chemical Industries), each of which has polyacrylic acid as the main unit; Hispagel (Hispano Chimica) as an aqueous solution of carboxyvinyl polymers; and U-Jelly CP (Showa Denko) as an aqueous solution of a polymer similar to carboxyvinyl polymers. One type of carboxyvinyl polymer may be used alone, or two or more types may be used in combination.

[0022] When a carboxyvinyl polymer is used in the present invention, the carboxyvinyl polymer can be dispersed or dissolved in water and used as is or after neutralization with a base. In this case, the base used as the neutralizing agent includes inorganic bases such as sodium hydroxide, potassium hydroxide, and aqueous ammonia; and organic bases such as triethanolamine, diethanolamine, diisopropanolamine, triisopropanolamine, and arginine, preferably organic bases, and more preferably triethanolamine.

[0023] In the topical composition of the present invention, the content of component (B) is not particularly limited and may be determined appropriately depending on the type of thickener, but may be, for example, 0.05 to 2% by weight, preferably 0.1 to 1% by weight, more preferably 0.3 to 0.8% by weight, and even more preferably 0.3 to 0.55% by weight.

[0024] (C) Solid hydrocarbon oil The topical composition of the present invention contains a solid hydrocarbon oil as component (C). When blended into a topical composition containing urea and a thickener, the solid hydrocarbon oil exhibits an excellent effect of inhibiting viscosity reduction.

[0025] A solid hydrocarbon oil is a hydrocarbon oil that remains solid at 25° C. The solid hydrocarbon oil used in the present invention may be any oil that is commonly used in cosmetics, topical medicines, etc., and examples thereof include petrolatum, ozokerite, ceresin, paraffin, polyethylene wax, microcrystalline wax, and gelled hydrocarbons.

[0026] These solid hydrocarbon oils may be used alone or in combination of two or more.

[0027] Among these components (C), from the viewpoint of obtaining further improved viscosity suppression properties, preferred are petrolatum, ozokerite, ceresin, paraffin, polyethylene wax, and microcrystalline wax, and more preferred is petrolatum. Furthermore, highly refined petrolatum, such as white petrolatum, is preferred as petrolatum.

[0028] In the topical composition of the present invention, the content of component (C) is not particularly limited and may be, for example, 0.1 to 20% by weight. From the viewpoint of obtaining even more improved viscosity suppression, the content of component (C) is preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, and even more preferably 5 to 8% by weight.

[0029] In the topical composition of the present invention, the ratio of component (A) to component (C) is not particularly limited and is determined depending on the respective contents of component (A) and component (C) described above. However, from the viewpoint of obtaining even more improved viscosity suppression properties, the content of component (C) per 1 part by weight of component (A) is 0.01 to 1 part by weight, preferably 0.05 to 0.8 parts by weight, and more preferably 0.25 to 0.5 parts by weight.

[0030] When the topical composition of the present invention contains the (E) component described below, the content of the (C) component per 100 parts by weight of the total of the (C) component and the (E) component is not particularly limited and is determined depending on the respective contents of the (C) component and the (E) component described below. However, from the viewpoint of obtaining even more improved viscosity suppression, the content of the (C) component per 100 parts by weight of the total of the (C) component and the (E) component is 3 to 50 parts by weight, preferably 10 to 40 parts by weight, and more preferably 15 to 30 parts by weight.

[0031] (D)Water The topical composition of the present invention may contain water (hereinafter also referred to as "component (D)"). Topical compositions containing urea and a thickener undergo a significant decrease in viscosity in the presence of water, but the topical composition of the present invention can effectively suppress this decrease in viscosity even when it contains water.

[0032] When the topical composition of the present invention contains component (D), its content may be appropriately set depending on the formulation, and may be, for example, 30 to 70% by weight. From the viewpoint of obtaining even better viscosity reduction suppression, the content of component (D) is preferably 35 to 55% by weight, more preferably 40 to 50% by weight, and even more preferably 40 to 46% by weight.

[0033] (E) Oil The topical composition of the present invention may further contain an oil component other than the above-mentioned component (C) (hereinafter also referred to as "component (E)"). Component (E) can be used appropriately depending on the formulation, etc. For example, when the topical composition of the present invention is an emulsion composition, component (E) is used as the oil phase.

[0034] The oil used in the present invention is not particularly limited as long as it is pharmaceutically or cosmetically acceptable, and at least one selected from liquid oils and solid oils other than hydrocarbons can be used.

[0035] In the topical composition of the present invention, either a liquid oil or a non-hydrocarbon solid oil may be used as component (E), or both may be used in combination.

[0036] When the topical composition of the present invention contains component (E), its content is not particularly limited and may be appropriately set depending on the emulsion type, form, intended use, etc. when the topical composition of the present invention is an emulsion composition. For example, the content may be 0.1 to 40% by weight, preferably 1 to 30% by weight, and more preferably 10 to 27% by weight.

[0037] (liquid oil) Liquid oils are oils that remain liquid at 25° C. The liquid oils used in the present invention may be any oil commonly used in cosmetics, topical pharmaceuticals, etc., and examples thereof include vegetable oils such as avocado oil, camellia oil, macadamia nut oil, olive oil, and jojoba oil; fatty acids such as oleic acid and isostearic acid; ester oils such as cetyl ethylhexanoate, ethylhexyl palmitate, octyldodecyl myristate, neopentyl glycol diethylhexanoate, glyceryl tri-2-ethylhexanoate, octyldodecyl oleate, isopropyl myristate, glyceryl triisostearate, and glyceryl di-methylmethoxycinnamate-monoethylhexanoate; silicone oils such as dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, and octamethylcyclotetrasiloxane; liquid hydrocarbon oils such as liquid paraffin, squalene, and squalane; and higher alcohols such as lauryl alcohol.

[0038] Of these liquid oils, ester oil and liquid hydrocarbon oil are preferred; isopropyl myristate and liquid paraffin are more preferred.

[0039] These liquid oils may be used alone or in combination of two or more.

[0040] When liquid oil is contained in the topical composition of the present invention, the content thereof is not particularly limited, and may be appropriately set depending on the emulsion type, form, application, etc. when the topical composition of the present invention is an emulsion composition. For example, the content may be 0.1 to 30% by weight, preferably 1 to 25% by weight, and more preferably 10 to 20% by weight.

[0041] (solid oil other than hydrocarbons) A non-hydrocarbon solid oil is a non-hydrocarbon oil that remains in a solid form at 25°C. The solid oil other than hydrocarbons used in the present invention may be any oil typically used in cosmetics, topical pharmaceuticals, etc., and examples thereof include waxes such as candelilla wax, rice bran wax, beeswax, cotton wax, carnauba wax, lanolin, and shellac wax; higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, and undecylenic acid; ester oils such as myristyl myristate, cetyl myristate, stearyl stearate, cetyl stearate, cetyl palmitate, cholesteryl stearate, cholesteryl oleate, dextrin palmitate, inulin stearate, and hydrogenated jojoba oil; linear or branched higher alcohols such as cetyl alcohol, stearyl alcohol, behenyl alcohol, myristyl alcohol, cetostearyl alcohol, oleyl alcohol, and monostearyl glycerin ether (batyl alcohol); and silicone waxes.

[0042] Among these solid oils other than hydrocarbons, preferred are linear or branched higher alcohols, more preferred are linear higher alcohols, and even more preferred are cetanol and stearyl alcohol.

[0043] These non-hydrocarbon solid oils may be used singly or in combination of two or more.

[0044] When a solid oil is contained in the topical composition of the present invention, the content thereof is not particularly limited, and may be appropriately set depending on the emulsion type, form, application, etc. when the topical composition of the present invention is an emulsion composition. For example, the content may be 0.1 to 30% by weight, preferably 1 to 20% by weight, and more preferably 5 to 10% by weight.

[0045] (F) Surfactant The topical composition of the present invention further contains a surfactant (hereinafter also referred to as "component (F)"). Component (F) can be used appropriately depending on the formulation, etc. For example, when the topical composition of the present invention is an emulsion composition, component (F) is used to emulsify the composition. The surfactant is not particularly limited as long as it is pharmaceutically or cosmetically acceptable, and examples thereof include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, etc., and preferably nonionic surfactants.

[0046] Specific examples of nonionic surfactants include polyoxyethylene hydrogenated castor oil; sorbitan fatty acid esters (e.g., sorbitan monooleate, sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, diglycerol sorbitan penta-2-ethylhexylate, diglycerol sorbitan tetra-2-ethylhexylate, etc.); glycerin fatty acid esters (e.g., monoglyceryl cottonseed oil fatty acid, monoerucic acid, etc.); Glyceryl, glyceryl sesquioleate, glyceryl monostearate, α,α'-oleic acid pyroglutamate glyceryl, monostearate glyceryl malate, 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.); polyoxy Ethylene sorbitol fatty acid esters (e.g., polyoxyethylene sorbitol monolaurate, polyoxyethylene sorbitol monooleate, polyoxyethylene sorbitol pentaoleate, polyoxyethylene sorbitol monostearate, etc.); polyoxyethylene glycerol fatty acid esters (e.g., polyoxyethylene glycerol monostearate, polyoxyethylene glycerol monoisostearate, polyoxyethylene glycerol triisostearate, etc.); polyoxyethylene fatty acid esters (e.g., polyoxyethylene monooleate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monodioleate, ethylene glycol distearate, etc.); 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 types (e.g., Pluronic, etc.);Polyoxyethylene-polyoxypropylene alkyl ethers (e.g., polyoxyethylene-cetyl ether, polyoxyethylene-polyoxypropylene-2-decyltetradecyl ether, polyoxyethylene-polyoxypropylene monobutyl ether, polyoxyethylene-polyoxypropylene hydrogenated lanolin, polyoxyethylene-polyoxypropylene glycerin ether, etc.); polyglycerin fatty acid esters (e.g., polyglyceryl-2 stearate, polyglyceryl-2 oleate, polyisostearate, etc.); Examples include polyglyceryl-2 triisostearate, polyglyceryl-2 triisostearate, polyglyceryl-4 stearate, polyglyceryl-4 oleate, polyglyceryl-6 tristearate, polyglyceryl-10 stearate, polyglyceryl-10 pentastearate, polyglyceryl-10 pentahydroxystearate, polyglyceryl-10 pentaisostearate, polyglyceryl-10 pentaoleate, polyglyceryl-6 polyricinoleate, polyglyceryl-10 polyricinoleate, steareth-21, etc.;

[0047] Among these nonionic surfactants, polyoxyethylene hydrogenated castor oil and polyoxyethylene sorbitan fatty acid esters are preferred, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan tetraoleate are more preferred, and polyoxyethylene hydrogenated castor oil and polyoxyethylene sorbitan monostearate are even more preferred.

[0048] These surfactants may be used alone or in combination of two or more.

[0049] When the topical composition of the present invention contains component (F), its content may be appropriately determined depending on the formulation and the type of surfactant used, and may be, for example, 0.5 to 7% by weight, preferably 1 to 5% by weight, and more preferably 2 to 5% by weight.

[0050] Other ingredients In addition to the above-mentioned components, the topical composition of the present invention may contain other commonly used additives as needed, such as pH adjusters, polyhydric alcohols, buffers, solubilizers, chelating agents, preservatives, antioxidants, stabilizers, fragrances, and colorants.

[0051] Furthermore, in the topical composition of the present invention, it is preferable that other additives such as hydroxy acids such as citric acid, malic acid, tartaric acid, lactic acid, and mevalonic acid are not contained, in order to avoid skin irritation.

[0052] Furthermore, the topical composition of the present invention may contain, in addition to the above-mentioned components, active ingredients capable of exerting pharmaceutical or cosmetic physiological functions, if necessary. Examples of such medicinal ingredients include steroids (dexamethasone, dexamethasone hydrochloride, dexamethasone acetate, hydrocortisone hydrochloride, prednisolone valerate, prednisolone acetate, etc.), antihistamines (diphenhydramine, chlorpheniramine maleate, etc.), local anesthetics (lidocaine, dibucaine, procaine, tetracaine, bupivacaine, mepivacaine, chloroprocaine, proparacaine, meprylcaine, or salts thereof), alkyl benzoates (e.g., ethyl aminobenzoate, diethylaminoethyl p-butylaminobenzoate hydrochloride), orthocaine, oxethazaine, oxypolyethylenedioxydecane, Scopolia extract, percaminpase, tesitdesitin, etc.), anti-inflammatory agents (allantoin, salicylic acid, glycol salicylate, etc.), and the like. Examples of effective active ingredients include chol, methyl salicylate, indomethacin, felbinac, diclofenac sodium, loxoprofen sodium, etc.), disinfectants (benzalkonium chloride, dequalinium chloride, benzethonium chloride, cetylpyridinium chloride, isopropylmethylphenol, chlorhexidine hydrochloride, chlorhexidine gluconate, aqueous ammonia, sulfadiazine, lactic acid, phenol, etc.), antipruritics (diphenhydramine, crotamiton, thianthol, etc.), skin protectants (collodion, castor oil, etc.), blood circulation promoting ingredients (vanillyl nonylate amide, nicotinic acid benzyl ester, capsaicin, chili pepper extract, etc.), vitamins (vitamins A, B, C, D, etc.), mucopolysaccharides (sodium chondroitin sulfate, glucosamine, hyaluronic acid, etc.). These active ingredients may be used alone or in combination of two or more. Furthermore, when these medicinal ingredients are contained in the external composition of the present invention, the content thereof may be appropriately determined depending on the type of medicinal ingredient used, the desired effect, etc.

[0053] Formulation and Use The formulation of the topical composition of the present invention is not particularly limited as long as it has a certain degree of viscosity, and examples thereof include oily gel compositions, emulsion compositions, etc. Topical compositions containing urea and a thickener significantly suppress viscosity loss in the presence of water, but the topical composition of the present invention can effectively suppress viscosity loss even when containing water. In view of the effects of the present invention, a preferred formulation of the topical composition of the present invention is an emulsion composition. When the topical composition of the present invention is an emulsion composition, the emulsion type may be either oil-in-water or water-in-oil, but in view of the effects of the present invention, a preferred emulsion type is an oil-in-water emulsion type with a relatively high water content.

[0054] The viscosity of the topical composition of the present invention is not particularly limited, but from the viewpoint of obtaining good application properties, it is preferably 1,000 to 50,000 mPa·s, more preferably 3,000 to 30,000 mPa·s, and even more preferably 7,000 to 15,000 mPa·s. Here, the viscosity is a value measured at 25°C using an E-type viscometer (spindle No. RC3-50-1, 1 rpm).

[0055] The topical composition of the present invention can be used as an external preparation such as a cosmetic, topical quasi-drug, or topical pharmaceutical. Because the topical composition of the present invention has an excellent viscosity reduction suppression effect, it can effectively suppress viscosity reduction even when it contains a relatively large amount of urea, which would otherwise significantly reduce viscosity. In view of these effects of the present invention, the topical composition of the present invention is preferably used as an external pharmaceutical with a high urea content.

[0056] The product form of the topical composition of the present invention is not particularly limited, and examples thereof include creams, ointments, emulsions, gels, oils, lotions, liniments, aerosols, etc. Among these, creams, ointments, emulsions, and lotions are preferred, creams, emulsions, and lotions are more preferred, and creams and emulsions are even more preferred.

[0057] Manufacturing method The topical composition of the present invention can be prepared according to known formulation techniques, depending on the formulation form. For example, the topical composition of the present invention can be prepared by mixing the desired amounts of the above-mentioned components (A) to (C), the optional components (D) to (F), the above-mentioned other medicinal ingredients, additives, etc. When the topical composition of the present invention is an emulsion composition, it can be prepared according to known emulsion formulation techniques, depending on the emulsion type. For example, when the topical composition of the present invention is an emulsion composition, a method for preparing the topical composition of the present invention includes 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 them according to known techniques.

[0058] 2.Method for suppressing viscosity reduction As described above, when a solid hydrocarbon oil is incorporated into a topical composition containing urea and a thickener, it exhibits an excellent effect of inhibiting viscosity loss. Therefore, the present invention further provides a method for inhibiting viscosity loss in a topical composition containing (A) urea and (B) a thickener, comprising incorporating (C) a solid hydrocarbon oil into the topical composition in addition to the components (A) and (B). In the method for inhibiting viscosity loss of the present invention, inhibiting viscosity loss means that a topical composition containing urea and a thickener exhibits a smaller viscosity loss rate after high-temperature storage than a composition that does not contain a solid hydrocarbon oil. The inhibition of viscosity loss can be measured, for example, by observing that the viscosity loss rate of a topical composition stored at 50°C for two weeks is less than 15%, preferably less than 5%, when the viscosity before storage is taken as 100%.

[0059] In the viscosity reduction suppression method of the present invention, the types and contents of the components (A) to (C) used, the types and contents of other components to be blended, the formulation form of the topical composition, etc. are the same as those in "1. Topical composition" above. [Example]

[0060] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to these examples.

[0061] Test Example 1 A topical composition was prepared with the composition shown in Table 1. Specifically, component (I) in Table 1 was mixed and stirred at 80°C until uniform to obtain an oily premix, and separately component (II) was mixed, followed by gradual addition of a carboxyl group polymer and stirring until uniform to obtain an aqueous premix. The aqueous premix was added to the oily premix and mixed until uniform, and triethanolamine was added and stirred until uniform to obtain a creamy emulsified topical composition.

[0062] (Evaluation of viscosity reduction suppression) The initial viscosity of the prepared topical compositions was measured. Specifically, the viscosity (initial viscosity) of the topical compositions was measured using a Brookfield E-type viscometer (R / S-CPS PLUS RHEOMETER) with a spindle No. RC3-50-1. The measurement conditions were a temperature of 25°C, a rotation speed of 1 rpm, and the viscosity was measured 1 minute after the start of measurement. For example, in Example 3, the initial viscosity was 10,150 mPa·s. The topical compositions were stored at 50°C for 2 weeks, and the viscosity of the topical compositions after storage was measured in the same manner. The viscosity reduction rate after storage was calculated, assuming the initial viscosity to be 100%. The viscosity reduction rate was classified according to the following criteria to evaluate the viscosity reduction inhibition. The results are shown in Table 1. ◎: Less than 5% ○: 5% or more but less than 15% △: 15% or more but less than 25% ×: 25% or more

[0063] [Table 1]

[0064] As shown in Table 1, the topical composition containing a thickener but no urea (Comparative Example 1) did not show any viscosity reduction problem after high-temperature storage, but the topical composition containing urea (Comparative Example 1) showed a significant viscosity reduction after high-temperature storage. In contrast, the topical compositions containing white petrolatum in addition to urea and a thickener (Examples 1 to 4) showed an excellent viscosity reduction effect after high-temperature storage.

Claims

1. (A) urea, (B) a water-soluble thickener comprising a carboxyvinyl polymer, and (C) a solid hydrocarbon oil, The content of the component (C) per 1 weight of the component (A) is 0.25 to 1 weight part, The content of the component (A) is 15 to 40% by weight, and A topical composition containing the component (B) in an amount of 0.05 to 0.55% by weight (excluding topical skin preparations containing an extract of a Cinchona plant, emulsion compositions containing an ester oil of a branched fatty acid and a linear alcohol, and topical compositions used for treating onychomycosis).

2. The topical composition according to claim 1, wherein the component (C) is petrolatum.

3. The topical composition according to claim 1 or 2, wherein the content of component (C) is 0.01 to 20% by weight.

4. The composition for external use according to any one of claims 1 to 3, which is an emulsion composition.

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