Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1992-06-17
1995-10-17
Dees, Jose G.
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424490, 424494, 424497, 424495, 424498, 514675, A61K 742
Patent
active
054588723
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to dihydroxyacetone (DHA), and particularly to its cosmetic applications.
BACKGROUND OF THE INVENTION
The dihydroxyacetone has been used for many years in cosmetology for its skin pigmentation properties and has become a tanning agent used in what is usually called suntan creams.
Such a use of the dihydroxyacetone is faced with many difficulties due to its solubility in water, its oxidizing capacity, its weakness when subjected to heat, the instability of its pH, its sensitivity to microbial and bacterial agents, etc. These difficulties require using the product containing dihydroxyacetone very quickly after its preparation, the portion of dihydroxyacetone which remains active diminishing very rapidly with time. Moreover, the product has to be stored in optimum conditions of temperature and hygrometry in order to avoid the decomposition and/or dehydration of the aqueous solution of dihydroxyacetone.
In order to facilitate the use of dihydroxyacetone in the cosmetology industry, it is therefore necessary to remedy at least some of these disadvantages. The works carried out in this respect have resulted into the present invention.
SUMMARY OF THE INVENTION
To this effect, the invention relates to a method for the protection and stabilization of the dihydroxyacetone (DHA), characterized in that a portion at least of the dihydroxyacetone in the dimer form imbedded in a watertight composition which releases the dihydroxyacetone when applied.
The watertight composition protects the DHA from water and oxidation and forms an envelope ensuring a certain thermal insulation.
According to a preferred embodiment of the method of this invention, the watertight composition is soluble in a solvent.
Preferably, said watertight composition contains a mixture of polymers insoluble in water such as: cellulose acetophthalate, vinylidene polychloride, styrene-acrylonitrile copolymers, copolymers of dimethylaminoethylmethacrylate and other neutral esters of methacrylic acid, cellulose acetate, nitrocellulose, ethylhydroxyethyl cellulose and ethyl cellulose.
Advantageously, the watertight composition contains ethyl cellulose in a concentration of 0,1% to 10%, preferably of about 2%, with respect to the weight of DHA.
DETAILED DESCRIPTION OF THE INVENTION
In order to facilitate the release of DHA when applied on the skin, one has to ensure that the watertight composition contains oily fats having a set fusion point such as a mixture of monoglycerides, diglycerides or triglycerides of saturated or unsaturated fatty acids having a chain with a length between C.sub.9 and C.sub.22, preferably between C.sub.12 and C.sub.18, and one controls the fusion point and the hardness by adding hydrocarbons derived from petroleum, from silicones and derivatives thereof, from mineral, vegetable or animal waxes and/or from fatty alcohols, from their long chain esters and from saturated or unsaturated fatty acids, for example lauric, myristic, palmitic, oleic or stearic acid, and particularly stearic acid in a concentration of 1% to 15%, preferably of about 7%, with respect to the weight of DHA.
Advantageously, in order to stabilize the pH in a zone between acid and neutral inside of and in the immediate vicinity of the watertight composition, the invention provides that the composition contains an organic acid or one of its salts such as acids-phenols, acids-alcohols, or a precursor of such an acid in the form of lactone, particularly the glucuno-delta-lactone in a concentration of 0,01% to 2%, and preferably of about 0,15% with respect to the weight of DHA.
According to a preferred embodiment of the method according to the invention, and to avoid the bacterial degradation of DHA, one sees that said watertight composition contains a bacteriostatic and/or a bactericide and/or a fungicidal agent compatible with the use in cosmetology, such as the derivatives of isothiazolone, the formaldehyde generating products, the organic and mineral derivatives of mercury, bromine, chlorine, the acids,
REFERENCES:
patent: 4434154 (1984-02-01), Mc Shane
patent: 4855090 (1989-08-01), Wallach
patent: 4911928 (1990-03-01), Wallach
patent: 5093107 (1992-03-01), Matravers
Derwent; WPI; AN-90-099893; 1989.
Hawley's Condensed Chemical Dictionary elventh edition; 1987; selected pages.
Beilstein: "Handbuch Der Organischen Chemie", Edition 4, vol. 1, 1918, by Julius Springer, p. 846, paragraph 6.
Chemical Abstracts, "Study on dihydroxyacetone preservation as a function of formulation", vol. 100, No. 8 of Feb. 20, 1984 by M. F. Bobin et al., p. 318, abstract 56724q.
Chemical Abstracts, "Stabilized preparation to tan the skin", vol. 72, No. 20, of May 18, 1970 by K. Hronsky, p. 223, abstract 10363b.
"Composition for Artificial Sun-Tan", World Patent Index Lates Database, Accession No. 83-825600, of week 47, sections D21,E19, 1983, by I. M. Erns et al.
Seifen-ole-Fette-Wachse, vol. 104, No. 9, Jun. 1978, p. 247, col. 2, lines 1-30.
Barts Samuel
Dees Jos,e G.
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