Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1995-08-04
1998-08-04
Dodson, Shelly A.
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424 60, 424400, 424401, A61K 742, A61K 700
Patent
active
057889520
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to cosmetic and dermatological sunscreen preparations, in particular skin-caring cosmetic and dermatological sunscreen preparations.
The damaging effect of the ultraviolet part of solar radiation on the skin is generally known. While rays having a wavelength which is smaller than 290 nm (the so-called UVC range) are absorbed by the ozone layer in the earth's atmosphere, rays in the range between 290 nm and 320 nm, the so-called UVB range, cause erythema, simple sunburn or even more or less severe burns.
The relatively narrow range around 308 nm is indicated as a maximum of the erythema activity of sunlight.
For protection against UVB radiation, numerous compounds are known which are mostly derivatives of 3-benzylidenecamphor, of 4-aminobenzoic acid, of cinnamic acid, of salicylic acid, of benzophenone and also of 2-phenylbenzimidazole.
Even for the range between approximately 320 nm and approximately 400 nm, the so-called UVA range, it is important to have available filter substances, as even its rays can produce damage. It has thus been shown that UVA radiation leads to damage to the elastic and collagenic fibres of the connective tissue, which can prematurely age the skin, and that it is to be regarded as the cause of numerous phototoxic and photoallergic reactions. The damaging effect of the UVB radiation can be increased by UVA radiation.
For protection against the rays of the UVA range, certain derivatives of dibenzoylmethane are therefore used whose photostability (Int. J. Cosm. Science 10, 53 (1988)) is not specified to an adequate extent.
The UV radiation, however, can also lead to photochemical reactions, the photochemical reaction products then intervening in the skin's metabolism.
Mainly, such photochemical reaction products are free-radical compounds, e.g. hydroxyl radicals. Even undefined free-radical photoproducts, which are formed in the skin itself, can have uncontrolled secondary reactions on account of their high reactivity. However, even singlet oxygen, a non-free-radical excited state of the oxygen molecule, can occur on UV irradiation, just like short-lived epoxides and many others. Singlet oxygen, for example, is distinguished compared with the normally present triplet oxygen (free-radical ground state) by increased reactivity. Of course, excited, reactive (free-radical) triplet states of the oxygen molecule also exist.
UV radiation is further counted as ionizing radiation. There is thus the risk that ionic species are also formed on UV exposure, which then for their part are able to intervene oxidatively in the biochemical processes.
In order to prevent these reactions, antioxidants and/or free-radical scavengers can additionally be incorporated into the cosmetic or dermatological formulations.
Most inorganic pigments are UV absorbers or UV reflectors, which, as is known, are used in cosmetics for the protection of the skin from UV rays. These are oxides of titanium, zinc, iron, zirconium, silicon, manganese, aluminium, cerium and mixtures thereof, and also derivatives.
The inorganic pigments are distinguished by good sunscreen action. However, they have the disadvantage that it is difficult to incorporate them into such formulations in a satisfactory manner.
A further disadvantage of the use of inorganic pigments in cosmetic formulations is that such pigments lead in by far the most cases to severe dryness of the skin.
As the pigment particles have to be efficiently prevented from accumulating to give agglomerates, a certain proportion of emulsifiers or comparable surface-active or interface-active substances always had to be added to the formulations.
Per se, the use of the customary cosmetic emulsifiers is harmless. Nevertheless, emulsifiers, in the end like any chemical substance, can produce allergic reactions or reactions based on hypersensitivity of the user in the isolated case.
Thus, it is known that specific photodermatoses are induced by certain emulsifiers, but also by various fats, and simultaneous exposure to sunlight. Such lig
REFERENCES:
patent: 5538716 (1996-07-01), Forestier et al.
Gers-Barlag Heinrich
Schulz Sabine
Beiersdorf AG
Dodson Shelly A.
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