Use of sunscreen combinations which comprise, as essential...

Details Use of sunscreen combinations which comprise, as essential... Use of sunscreen combinations which comprise, as essential...

2002-03-12

2002-12-03

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S060000, C424S400000, C424S401000

Reexamination Certificate

active

06488915

ABSTRACT:

Use of sunscreen combinations which comprise, as essential constituent, 2-(4-alkoxyanilinomethylene)malonic dialkyl esters as photostable UV filters in cosmetic and pharmaceutical preparations
The invention relates to the use of sunscreen combinations which comprise, as essential constituent, the 2-(4-alkoxyanilinomethylene)malonic dialkyl esters which absorb in the UV-A region, and at least one further sunscreen which absorbs in the UV-A region, UV-B region or in both regions, chosen from a group defined in detail below as photostable UV filter combination in cosmetic and pharmaceutical preparations for protecting the human epidermis or human hair against UV radiation, specifically in the range from 320 to 400 nm.
The sunscreens employed in cosmetic and pharmaceutical preparations have the task of preventing, or at least diminishing the consequences of, harmful effects of sunlight on the human skin. However, these sunscreens also serve to protect other ingredients from decomposition or degradation by UV radiation. In hair cosmetic formulations the aim is to reduce damage to the keratin fibers by UV rays.
The sunlight reaching the surface of the earth contains proportions of UV-B radiation (280 to 320 nm) and UV-A radiation (>320 nm), which are directly adjacent to the visible light region. The effect on the human skin is manifested, particularly in the case of UV-B radiation, by sunburn. Accordingly, the industry offers a relatively large number of substances which absorb UV-B radiation and thus prevent sunburn.
Dermatological investigations have now shown that UV-A radiation is also perfectly capable of causing skin damage and allergies by, for example, damaging the keratin or elastin. This reduces the elasticity and water storage capacity of the skin, i.e. the skin becomes less supple and tends to form wrinkles. The noticeably high incidence of skin cancer in regions where the sun's radiation is strong shows that damage to the genetic information in the cells is evidently also caused by sunlight, specifically by UV-A radiation. All these findings would therefore suggest the need to develop efficient filter substances for the UV-A region.
There is a growing demand for sunscreens for cosmetic and pharmaceutical preparations which can be used in particular as UV-A filters and whose absorption maxima ought therefore to be in the range from about 320 to 380 nm. In order to achieve the required effect using the minimum amount, sunscreens of this type ought additionally to have a high specific absorbance. Sunscreens for cosmetic products must also meet a large number of other requirements, for example good solubility in cosmetic oils, high stability of the emulsions produced with them, toxicological acceptability, and low intrinsic odor and low intrinsic color.
Another requirement which sunscreens must meet is adequate photostability. However, this is only inadequately ensured, if at all, with the UV-A-absorbing sunscreens hitherto available.
French Patent No. 2 440 933 describes 4-(1,1-dimethylethyl)-4′-methoxydibenzoylmethane as a UV-A filter. It is proposed to combine this specific UV-A filter, which is sold by GIVAUDAN under the name “PARSOL 1789”, with various UV-B filters in order to absorb all UV rays having a wavelength from 280 to 380 nm.
However, this UV-A filter does not have sufficient photochemical stability, when used alone or in combination with UV-B filters, to ensure sustained protection of the skin during sunbathing for prolonged periods, which means that repeated applications at regular and short intervals are required if effective protection of the skin from all UV rays is desired.
For this reason, EP-A-0 514 491 discloses the stabilization of the insufficiently photostable UV-A filters by adding 2-cyano-3,3-diphenylacrylic esters which themselves act as filters in the UV-B region.
It has furthermore already been proposed in EP-A-0 251 398 and EP-A-0 416 837 to combine chromophores absorbing UV-A radiation and UV-B radiation into one molecule using a linker. This has the disadvantage that firstly a free combination of UV-A and UV-B filters in the cosmetic preparation is no longer possible, and that difficulties in the chemical linkage of the chromophores allow only certain combinations.
It is an object of the present invention to propose sunscreens for cosmetic and pharmaceutical purposes which absorb in the UV-A region with high absorbance, which are photostable, have low intrinsic color, i.e. a sharp band structure, and are soluble in oil or water depending on the substituent.
We have found that this object can be achieved advantageously by certain sunscreen combinations.
Accordingly, this object is achieved according to the invention by the use of sunscreen combinations comprising a
A) compound absorbing essentially in the UV-A region and
B) further compounds absorbing in the UV-A region, in the UV-B region and over both regions,
 where the constituent absorbing in the UV-A region consists of
A) effective amounts of at least one of the compounds of the formula I
 in which the substituents R
1
to R
3
, independently of one another, are C
1
-C
8
-alkyl and the constituent
B) comprises effective amounts of one or more compounds chosen from the group consisting of
Ba) hydroxybenzophenones of the formula II
 in which the substituents, independently of one another, have the following meanings:
R
4
and R
5
are hydrogen, C
1
-C
12
-alkyl, C
3
-C
10
-cycloalkyl, where the substituents R
4
and R
5
may, together with the nitrogen atom to which they are bonded, form a 5- or 6-membered ring and
R
6
hydrogen, C
1
-C
12
-alkyl, C
3
-C
10
-cycloalkyl;
Bb) diarylbutadienes of the formula III
 in which the substituents R
7
and R
8
, independently of one another, may be hydrogen, C
1
-C
12
-alkyl or C
3
-C
10
-cycloalkyl,
Bc) the compound of the formula IV
Bd) the compound of the formula V
Be) the compound of the formula VI
Bf) the compound of the formula VII
Bg) an organosiloxane benzalmalonate of the formula VIIIa
 in which
V
1
′ is the group
V
1
is a methyl group or V
1
′, or of the formula VIIIb
 in which V
2
′ is the group of the structure
V
2
is a methyl group or V
2
′
or mixtures of compounds of the formulae VIIIa and VIIIb,
where t is a value up to 100 and u is a value up to 20, with the proviso that u=0 when V
1
=V
1
′ and/or V
2
=V
2
′, and u is a value from 1 to 20 when V
1
=CH
3
and/or V
2
=CH
3
,
Bh) the compound of the formula IX
Bi) the compound of the formula X
Bj) the compound of the formula XI
 in which X is hydrogen, sodium, potassium, ammonium or triethanolammonium,
Bk) the compound of the formula XII
 as photostable UV filters in cosmetic and pharmaceutical preparations for protecting human skin or human hair against UV rays, in particular against natural solar rays, optionally together with further compounds which absorb in the UV region and which are known per se for cosmetic and pharmaceutical preparations.
Alkyl radicals R
1
to R
3
in compound I which may be mentioned are branched or unbranched C
1
-C
8
-alkyl chains, preferably methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1methylpropyl, 1-ethyl-2-methylpropyl, n-heptyl or n-octyl. Preferred radicals for R
1
to R
3
are methyl, ethyl, n-propyl and 1-methylethyl.
Alkyl radicals R
4
, R
5
and R
6
in compound II which may be mentioned are branched or unbranched C
1
-C
12
-alkyl chains, preferably methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, n-pentyl, 1-

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