Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
1998-11-18
2001-01-30
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
06180090
ABSTRACT:
The present invention relates to light protection formulations, in particular to cosmetic and dermatological light protection compositions.
The damaging effect of the ultraviolet part of solar radiation on the skin is generally known. While rays having a wavelength of below 290 nm (the UVC region) are absorbed by the ozone layer in the Earth's atmosphere, rays in the region between 290 nm and 320 nm, the UVB region, cause erythema, simple sunburn or even burns of varying severity.
The maximum erythema activity of sunlight is in the narrower region around 308 nm.
Numerous compounds for protecting against UVB radiation are known; these are usually derivatives of 3-benzylidenecamphor, 4-aminobenzoic acid, cinnamic acid, salicylic acid, benzophenone and also 2-phenylbenzimidazole.
It is also important to have available filter substances, for the region between about 320 nm and about 400 nm, the UVA region, since the rays of that region can also cause damage. For example, it has been found that UVA radiation leads to damage of the elastic and collagenic fibres of connective tissue, causing premature ageing of the skin, and it is regarded as a cause of numerous phototoxic and photoallergic reactions. The damaging effect of UVB radiation can be intensified by UVA radiation.
For protecting against the rays of the UVA region, use is therefore made of certain derivatives of dibenzoylmethane, whose photostability (Int. J. Cosm. Science 10, 53 (1988)) is inadequate.
However, UV radiation can also lead to photochemical reactions, in which case the photochemical reaction products intervene in the skin's metabolism. Such photochemical reaction products are predominantly free-radical compounds, for example hydroxyl free radicals. Undefined free-radical photoproducts which are formed in the skin itself can also display uncontrolled secondary reactions because of their high reactivity. However, singlet oxygen, a non-radical excited state of the oxygen molecule, can also be formed during UV irradiation, as can short-lived epoxides and many others. Singlet oxygen, for example, differs from normal triplet oxygen (free-radical ground state) by its increased reactivity. However, excited, reactive (free-radical) triplet states of the oxygen molecule also exist.
In order to prevent these reactions, it is possible additionally to incorporate antioxidants and/or free-radical scavengers into the cosmetic or dermatological formulations.
Known and advantageous light protection substances are dibenzoylmethane derivatives, for example 5-isopropyidibenzoylmethane (CAS No. 63250-25-9), which is characterized by the structure
and is marketed by Merck under the name Eusolex® 8020, and also 4-(tert-butyl)-4′-methoxydibenzoylmethane (CAS No. 70356-09-1), which is characterized by the structure
and marketed by Givaudan under the name Parsol® 1789. However, in combination with other substances present as solids, their use concentration is limited. There are therefore certain formulation difficulties in achieving higher light protection factors.
Another advantageous light protection filter substance is 4-methylbenzylidenecamphor, which is characterized by the structure
and is marketed by Merck under the name Eusolex® 6300. 4-Methylbenzylidenecamphor is an extremely advantageous light protection filter substance, which is a solid under normal conditions and is notable per se for good UV filter properties. In combination with other solid substances, however, its use concentration too is limited. There are thus certain formulation difficulties in achieving higher light protection factors here as well.
Other benzylidenecamphor derivatives are also advantageous light protection filter substances, e.g. benzylidenecamphor, which is characterized by the structure
and is marketed by Induchem under the name Unisol® S22. In combination with other substances in the form of solids, however, its use concentration too is limited. There are thus certain formulation difficulties in achieving higher light protection factors here as well.
Another advantageous UV filter is tris(2-ethylhexyl) 4,4′, 4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, synonym: 2,4,6-tris[anilino(p-carbo-2′-ethyl-1′-hexyloxy)]-1,3,5-triazine.
This UVB filter substance is marketed by BASF Aktiengesellschaft under the trade name UVINUL® T 150 and is notable for good UV absorption properties. In the meantime, various authors have described other UV filter substances which have the structure
The main disadvantage of tris(2-ethylhexyl) 4,4′, 4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate is its poor solubility in lipids. Known solvents for this UVB filter can dissolve a maximum of about 15% by weight of this filter, corresponding to about 1-1.5% by weight of dissolved, and thus active, UV filter substance. There are thus certain formulation difficulties in achieving high light protection factors here as well.
Other UV filter substances which are in the form of solids, the incorporation of which into cosmetic or dermatological light protection formulations has at least certain problems, are also known. For example, EP-A-570 838 describes s-triazine derivatives, the chemical structure of which is given by the generic formula
where
R is a branched or unbranched C
1
-C
18
-alkyl radical, a C
5
-C
12
-cycloalkyl radical, optionally substituted with one or more C
1
-C
4
-alkyl groups,
X is an oxygen atom or an NH group,
R
1
is a branched or unbranched C
1
-C
18
-alkyl radical, a C
5
-C
12
-cycloalkyl radical, optionally substituted with one or more C
1
-C
4
-alkyl groups, or a hydrogen atom, an alkali metal atom, an ammonium group or a group of the formula
in which
A is a branched or unbranched C
1
-C
18
-alkyl radical, a C
5
-C
12
-cycloalkyl or aryl radical, optionally substituted with one or more C
1
-C
4
-alkyl groups,
R
3
is a hydrogen atom or a methyl group,
n is a number from 1 to 10,
R
2
is a branched or unbranched C
1
-C
18
-alkyl radical, a C
5
-C
12
-cycloalkyl radical, optionally substituted with one or more C
1
-C
4
-alkyl groups, when X is the NH group, and
a branched or unbranched C
1
-C
18
-alkyl radical, a C
5
-C
12
-cycloalkyl radical, optionally substituted with one or more C
1
-C
4
-alkyl groups, or a hydrogen atom, an alkali metal atom, an ammonium group or a group of the formula
in which
A is a branched or unbranched C
1
-C
18
-alkyl radical, a C
5
-C
12
-cycloalkyl or aryl radical, optionally substituted with one or more C
1
-C
4
-alkyl groups,
R
3
is a hydrogen atom or a methyl group,
n is a number from 1 to 10,
when X is an oxygen atom.
Even if it is in principle possible to achieve a certain UV protection for a given limited solubility (and thus, according to traditional standards, poor incorporability into a cosmetic or dermatological preparation), another problem may arise, that of recrystallization. In the case of sparingly soluble substances, this happens comparatively quickly, be it as a result of fluctuations in temperature or other influences. Uncontrolled recrystallization of an essential constituent of the preparation, such as a UV filter, does, however, have extremely disadvantageous effects on the properties of the given preparation and, not least, on the desired light protection.
Other UV filter substances, incorporation of which into cosmetic or dermatological light protection formulations has at least certain problems, are also known. For example, EP-A-775 698 describes bisresorcinyltriazine derivatives, the chemical structure of which is given by the generic formula
where R
1
, R
2
and A
1
represent a wide variety of organic radicals.
Advantageous bisresorcinyltriazine derivatives are, for example, the following compounds:
where R
3
is a hydrogen atom or a branched or unbranched alkyl group having from 1 to 10 carbon atoms, in particular 2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]-phenyl }-6-(4-methoxyphenyl)-1,3,5-triazine, which is characterized by the following structure:
Another advantageous compound is 2,4-bis{&lsqb
Gers-Barlag Heinrich
Kropke Rainer
Nielsen Jens
Scheel Oliver
Beiersdorf AG
Dodson Shelley A.
Norris McLaughlin & Marcus P.A.
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