JPH0899829A - Skin external agent - Google Patents

Abstract

PURPOSE: To obtain a skin external agent highly improved in the stability of the α-tocopheryl retinoate therein, formulated with an α-tocopheryl retinoate and water-soluble benzophenone-based compound(s). CONSTITUTION: This skin external agent contains pref. 0.001-10 (esp. 0.01-2.0) wt.% of an α-tocopheryl retinoate and pref. 0.001-5wt.% of at least one kind of water-soluble benzophenone-based compound (e.g. 2-hydroxy-4- methoxybenzophenone-5-sulfonic acid, sodium 2-hydroxy-4- methoxybenzophenone-5-sulfonate). The α-tocopheryl retinoate is an ingredient effective for preventing or treating keratosis and preventing or remedying skin aging, being improved in stability owing to formulation of the above compound(s) as additive, resulting in the aimed excellent skin external preparation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external preparation for skin in which the stability of α-tocopheryl retinoate is remarkably improved.

[0002]

BACKGROUND OF THE INVENTION It is known that α-tocopheryl retinoate is an effective component for prevention and treatment of cutaneous keratoses, prevention of skin aging and recovery. Compounds used as pharmaceutical and cosmetic ingredients (Japanese Patent Publication No. 59-22684, Japanese Patent Publication No. 53-15429, and Japanese Patent Publication No. 54-84034).
JP-A No. 2-300123, etc.).

However, as is well known, α-
Tocopheryl retinoate is structurally extremely unstable and easily undergoes hydrolysis, various isomerizations and polymerization due to light, air, heat, metal ions, etc., resulting in a decrease in activity during storage. However, it was difficult to stably mix it with the external preparation for skin. Therefore, conventionally, attempts have been made to improve the storage stability of α-tocopheryl retinoate. For example, an antioxidant such as ascorbic acid or tocopherol may be allowed to coexist (see JP-A-2- 300
123) and coexistence of carotenoids to enhance stability against light etc. (Japanese Patent Laid-Open No. 163143/1993).
No. publication) is known. However, the former method of coexisting antioxidants is insufficient in its stabilizing effect, and the latter method of adding carotenoids has
Even if the compounding amount is about 01% by weight, the base is colored, and if it is tried to mix the necessary amount for obtaining the desired stabilizing effect, it cannot avoid a considerable amount of coloring, and is excessive in the nature as an external preparation for skin. Considering that coloring should be avoided,
There is a problem that a large amount of carotenoid cannot be blended. A satisfactory method for stabilizing α-tocopheryl retinoate has not yet been found, and development of an excellent stabilizing means is desired.

[0004]

Means for Solving the Problems As a result of intensive studies in view of the present circumstances, the present inventors have found that if one or more water-soluble benzophenone compounds are blended with α-tocopheryl retinoate, α- The inventors have found that the stability of tocopheryl retinoate is significantly improved, and have completed the present invention.

That is, the gist of the present invention resides in an external preparation for skin characterized in that α-tocopheryl retinoate and one or more water-soluble benzophenone compounds are blended.

The structure of the present invention will be described in detail below. The α-tocopheryl retinoate used in the present invention means α
An ester of tocopherol and vitamin A acid, α
-Tocopheryl retinoate is a natural mixed tocopherol containing DL-α-tocopherol, D-α-tocopherol or D-α-tocopherol, and vitamin A acid is retinoic acid or all-trans-retinoic acid, 13- cis-retinoic acid, 11-cis-retinoic acid, 9
-cis-retinoic acid or mixed isomers containing them. Among them, DL-α-tocopherol and all-tran
Most preferred is the ester of s-retinoic acid.

Α blended in the external preparation for skin according to the present invention
-The amount of tocopheryl retinoate is not particularly limited, but considering the effect of α-tocopheryl retinoate on the skin, it is 0.0001% by weight or more, and the effect of α-tocopheryl retinoate is strongly appealed. In order to achieve this, the content is preferably 0.001% by weight, more preferably 0.1%.
It is at least 01% by weight. The upper limit of compounding is 10% by weight or less, preferably 5.0% by weight, due to its properties as a skin external preparation.
Up to 2.0% by weight, more preferably up to 2.0% by weight.

The water-soluble benzophenone compound used in the present invention is 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (hereinafter benzophenone-4).
And a salt thereof, sodium 2-hydroxy-4-methoxybenzophenone-5-sulfonate (hereinafter referred to as benzophenone-5), disodium 2,2′-dihydroxy-4,4′-dimethoxybenzophenone-5,5′-disulfonate ( Examples thereof include benzophenone-9).

The amount of the water-soluble benzophenone compounded in the external preparation for skin of the present invention is preferably 0.001% by weight or more, and an excessive amount thereof does not impair the effects of the present invention. However, when blended in an extremely large amount,
Since the problem of quality as an external preparation for the skin may occur due to precipitation of crystals and the like, it is usually preferably 5% by weight or less.

The effect of benzophenone in the present invention will be described. As shown in the examples below, the effect of benzophenone is not a contribution as a known ultraviolet absorber because the stability-improving effect of α-tocopheryl retinoate is exhibited under storage conditions under light-shielding. This is clear and a big discovery according to the present invention.

The external preparation for skin of the present invention contains, in addition to the above-mentioned essential components, other components usually used in cosmetics and quasi drugs, such as moisturizers, surfactants, preservatives, water, alcohols, Thickeners, oils, chemicals, chelating agents, fragrances, coloring agents, ultraviolet absorbers and the like can be added, if necessary, within a range that does not impair the effects of the present invention.

[0012]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention.

The production method of Examples 1 and 2 and Comparative Examples 1 and 2
Temperature test method Octyl methoxy cinnamate, oleyl alcohol, methyl paraben and POE (20) octyl dodecyl ether were completely dissolved in ethanol at 40 ° C., and then retinol acetate was completely dissolved and quickly cooled to obtain an alcohol part. The alcohol part was added to the water part in which the other components were dissolved in purified water, then the sample part was sealed in a brown glass sample tube, further wrapped with aluminum foil and completely shielded from light, and stored in a constant temperature bath at 40 ° C.

[0014]

[Table 1]

Quantitative method of α-tocopheryl retinoate It was quantified by reverse phase high performance liquid chromatography (HPLC) using a UV detector.

In Examples 1 and 2, the stability of α-tocopheryl retinoate is improved as compared with Comparative Examples, which is an effect according to the present invention.

Production methods of Examples 3 and 4 and Comparative Examples 3 and 4
Temperature test method After completely dissolving each oily component including BHT and the surfactant at 70 ° C., α-tocopheryl retinoate is completely dissolved immediately before emulsification to obtain an oil phase. Glycerin, propylene glycol, carboxyvinyl polymer, caustic potash, benzophenone-9 and benzophenone-5 were completely dissolved in purified water, and the oil phase was added to the aqueous phase heated to 70 ° C. and emulsified by a homomixer type emulsifier. Then by heat exchanger 3
A cooling treatment is performed to 0 ° C. to obtain an emulsion. The emulsion is filled in a metal-coated glass bottle, sealed, and stored in a constant temperature bath at 40 ° C.

[0018]

[Table 2]

Quantitative method of α-tocopheryl retinoate It was quantified by reverse phase high performance liquid chromatography (HPLC) using a UV detector.

In Examples 3 and 4, the stability of α-tocopheryl retinoate is improved as compared with Comparative Examples, which is an effect according to the present invention.

Example 5 Lotion (wt%) Oleyl alcohol 0.002 α-tocopheryl retinoate 0.0001 POE (50) oleyl ether 0.7 lactic acid 0.01 trisodium citrate 0.09 ethanol 8 Glycerin 2 Methylparaben 0.2 Benzophenone-12 2.5 Benzophenone-5 2.5 Purified water Amount based on 100 as a whole

Example 6 Oil Essence (wt%) 2-Ethylhexanoic acid triglyceride 30 Isopropyl myristate 30 Dibutyl phthalate 10 α-Tocopheryl retinoate 10 Diglycerin diisostearate 5 Dipropylene glycol 14.997 Benzophenone -4 0.001 trisodium citrate 0.002

Example 7 Cream (wt%) Squalane 15 2-Ethylhexanoic Acid Triglyceride 8 Isopropylmyristate 7 α-Tocopherol 0.05 Tocoretinate 0.3 Vaseline 2 Butylparaben 0.1 Propylparaben 0.1 Oleic Acid Monoglyceride 3 Diglycerin diisostearate 2 PEG400 Dioleate 1 Glycerin 10 Dipropylene glycol 5 Disodium edetate 0.01 Benzophenone-4 0.03 Triethanolamine 0.04 Purified water 100 parts by weight

Example 8 Oil gel (wt%) 2-Ethylhexanoic acid triglyceride 60 POE (20) Octyldodecyl ether 16 α-tocopheryl retinoate 0.1 Glycerin 16 Benzophenone-5 0.05 Purified water Amount to be 100

Example 9 Lotion (% by weight) Oleyl alcohol 0.002 α-tocopheryl retinoate 0.0001 POE (50) oleyl ether 0.7 lactic acid 0.01 trisodium citrate 0.09 ethanol 8 Glycerin 2 Methylparaben 0.2 Benzophenone-12 0.5 Benzophenone-5 0.5 Purified water Amount based on 100 as a whole

Example 10 Oil Essence (wt%) 2-Ethylhexanoic acid triglyceride 35 Isopropyl myristate 34 Dibutyl phthalate 10 α-Tocopheryl retinoate 1 Diglycerin diisostearate 5 Dipropylene glycol 14.997 Benzophenone -4 0.001 trisodium citrate 0.002

The skin external preparations of Examples 5 to 10 were excellent in the stability of α-tocopheryl retinoate in daily use.

[0028]

INDUSTRIAL APPLICABILITY In the external preparation for skin of the present invention, the stability of α-tocopheryl retinoate can be remarkably improved by incorporating a water-soluble benzophenone compound.

Claims (1)

[Claims] 1. With α-tocopheryl retinoate,
An external preparation for skin, which comprises one or more water-soluble benzophenone compounds.