Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2001-03-23
2003-05-27
Dees, Jose G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S401000
Reexamination Certificate
active
06569409
ABSTRACT:
The present invention relates, among other subject matters, to novel cosmetic compositions for topical use specifically intended for the photoprotection of the skin and/or hair against ultraviolet radiation (compositions hereinbelow known more simply as antisun compositions or screening compositions), to their use in the abovementioned cosmetic application and to a general process for the photostabilization of specific sunscreen agents, active in the UV-A region, by means of one or more suitably selected compounds.
More specifically still, it relates to antisun compositions which are photostable with regard to UV radiation and which comprise, in a cosmetically acceptable vehicle, at least one oily phase and at least one compound of the type derived from dibenzoylmethane, in combination with at least one specific thickening copolymer, as photostabilizing agent. It also relates to the corresponding process for the stabilization of said UV-A screening agent or agents by means of said thickening polymer or polymers.
It is known that UV-A rays with wavelengths of between 320 and 400 nm cause tanning of the skin but that they are also capable of inducing, in the long term, a detrimental change in the latter, in particular in the case of sensitive skin or of skin continually exposed to solar radiation. UV-A rays cause in particular a loss of elasticity of the skin and the appearance of wrinkles, leading to premature ageing. In addition, they promote triggering of the erythematous reaction or accentuate this reaction in some subjects and can even be the cause of phototoxic or photo-allergic reactions. It is thus desirable to screen out UV-A radiation.
Numerous organic sunscreen agents capable of absorbing harmful UV-A rays more or less selectively have been provided to date in the field of cosmetics.
In this respect, a particularly advantageous family of UV-A screening agents is currently composed of dibenzoylmethane derivatives and in particular 4-(tert-butyl)-4′-methoxydibenzoylmethane; this is because these derivatives exhibit a high intrinsic absorption power. These dibenzoylmethane derivatives are now products which are well known per se as lipophilic screening agents active in the UV-A region and are disclosed in particular in French patent applications FR-A-2 326 405 and FR-A-2 440 933 and in European patent application EP-A-0 114 607; furthermore, 4-(tert-butyl)-4′-methoxydibenzoylmethane is currently offered for sale under the trade name of “Parsol 1789” by Givaudan.
Unfortunately, it is found that dibenzoylmethane derivatives are products which are relatively sensitive to ultraviolet radiation (in particular UV-A radiation), that is to say, more specifically, that they have an unfortunate tendency to decompose more or less rapidly under the effect of the latter. Thus, this substantial lack of photochemical stability of dibenzoylmethane derivatives in the face of ultraviolet radiation, to which they are naturally intended to be subjected, does not make it possible to guarantee constant protection during prolonged exposure to the sun, so that repeated applications at regular and frequent intervals have to be carried out by the user in order to obtain effective protection of the skin against UV rays.
The photostabilization of dibenzoylmethane derivatives with respect to UV radiation constitutes, to date, a problem which has not yet been solved in a completely satisfactory manner.
In point of fact, the Applicant Company has now just discovered, unexpectedly and surprisingly, that, by combining the abovementioned dibenzoylmethane derivatives, in a vehicle comprising at least one oily phase, with an effective amount of at least one specific thickening polymer which will be defined in more detail below, it is possible to improve, substantially and notably, the photochemical stability (or photostability) of these same dibenzoylmethane derivatives without affecting the stability over time of their photoprotective effectiveness in the UV-A region.
This essential discovery forms the basis of the present invention.
Thus, in accordance with one of the subject matters of the present invention, a novel process for the stabilization of dibenzoylmethane derivatives with respect to UV radiation (wavelengths of between 280 nm and 400 nm approximately), in particular solar radiation, when these screening agents are present in a vehicle comprising at least one oily phase, is now provided, said process being essentially characterized in that it consists in combining said dibenzoylmethane derivatives with an effective amount of at least one specific thickening polymer which will be defined in more detail below.
In accordance with another subject matter of the present invention, novel photostable screening cosmetic compositions intended for the protection of the skin and/or hair against ultraviolet radiation, in particular solar radiation, are also provided, of the type comprising, in a cosmetically acceptable vehicle, at least one dibenzoylmethane derivative and at least one oily phase, which compositions are essentially characterized in that they additionally comprise an effective amount of at least one specific thickening copolymer which will be defined in more detail below.
The expression “effective amount of thickening copolymer in accordance with the invention” is understood to mean an amount sufficient to produce a notable and significant improvement in the photostability of the dibenzoylmethane derivative or derivatives of the photoprotective cosmetic composition. This minimum amount of stabilizing agent to be employed, which can vary according to the nature of the cosmetically acceptable vehicle used for the composition, can be determined without any difficulty by means of a conventional test for the measurement of photostability, such as that given in the examples below.
Yet another subject matter of the present invention is an improved cosmetic treatment process for the protection of the skin and/or hair against ultra-violet radiation, in particular solar radiation, which consists essentially in applying, to the latter, an effective amount of a photostable composition in accordance with the invention.
Finally, another subject matter of the present invention is the use of the same specific thickening polymers for stabilizing, with respect to UV rays, a dibenzoylmethane derivative present in a cosmetic composition comprising at least one oily phase.
Other characteristics, aspects and advantages of the present invention will become apparent on reading the detailed description which will follow.
As indicated above, the dibenzoylmethane derivatives intended to be photostabilized in the context of the present invention are products which are already well known per se and which are disclosed in particular in the abovementioned documents FR-A-2 326 405, FR-A-2 440 933 and EP-A-0 114 607, the teachings of which documents are, as regards that which affects the actual definition of these products, entirely included by way of references in the present description.
According to the present invention, one or more dibenzoylmethane derivatives can, of course, be employed.
Mention may in particular be made, among the dibenzoylmethane derivatives coming particularly well within the scope of the present invention, without implied limitation, of:
2-methyldibenzoylmethane
4-methyldibenzoylmethane
4-isopropyldibenzoylmethane
4-tert-butyldibenzoylmethane
2,4-dimethyldibenzoylmethane
2,5-dimethyldibenzoylmethane
4,4′-diisopropyldibenzoylmethane
4,4′-dimethoxydibenzoylmethane
4-tert-butyl-4′-methoxydibenzoylmethane
2-methyl-5-isopropyl-4′-methoxydibenzoylmethane
2-methyl-5-tert-butyl-4′-methoxydibenzoylmethane
2,4-dimethyl-4′-methoxydibenzoylmethane
2,6-dimethyl-4-tert-butyl-4′-methoxydibenzoylmethane
Preference is very particularly given according to the present invention, among the abovementioned dibenzoylmethane derivatives, to the use of 4-(tert-butyl)-4′-methoxydibenzoylmethane, in particular that offered for sale under the trade name of “Parsol 1
Hansenne Isabelle
Josso Martin
Burns Doane Swecker & Mathis L.L.P.
Dees Jos,e G.
George Konata M.
Societe L'Oreal S.A.
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