Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1995-11-27
1998-03-10
Dodson, Shelley A.
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424 60, 424 47, 424400, 424401, 424DIG5, 514159, 514241, 514245, 514408, 514532, 514679, 514692, A61K 742, A61K 744
Patent
active
057258449
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to water-resistant cosmetic or dermatological light protection formulations, in particular such light protection formulations in the form of emulsions or hydrodispersions.
Cosmetic skin care is primarily to be understood as intensifying or restoring the natural function of skin as a barrier against environmental influences (for example dirt, chemicals, microorganisms) and against the loss of endogenous substances (for example water, natural fats, electrolytes).
If this function is impaired, increased absorption of toxic or allergenic substances or attack by microorganisms and, as a consequence, toxic or allergic skin reactions may occur.
The aim of cosmetic skin care is furthermore to compensate the loss of fats and water from the skin caused by daily washing. This is important especially if the natural regeneration capacity is inadequate. Skin care products furthermore should protect against environmental influences, in particular sun and wind, and delay the signs of ageing of the skin.
Medicinal topical compositions as a rule comprise one or more medicaments in an active concentration. For simplicity, reference is made to the legal regulations of the Federal Republic of Germany (for example cosmetics legislation, Food and Drugs Act) for a clear distinction between cosmetic and medicinal use and corresponding products.
The damaging effect of the ultraviolet part of solar radiation on the skin is generally known. While rays having a wavelength shorter 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 burns of greater or lesser severity on the skin.
The narrower range around 308 nm is regarded as a maximum of the erythema activity of sunlight.
Numerous compounds are known for protection against UVB radiation, most of these being derivatives of 3-benzylidenecamphor, of 4-aminobenzoic acid, of cinnamic acid, of salicylic acid, of benzophenone and also of 2-phenylbenzimidazole.
UV filter substances are also important for the wavelength range between about 320 and 400 nm, the so-called UVA range, since such rays can also cause damage. It has thus been proved that UVA radiation leads to damage to the elastic and collagenic fibers of the connective tissue, which makes the skin age prematurely and is to be regarded as a cause of numerous phototoxic and photoallergic reactions. The damaging influence of UVB radiation may be intensified by UVA radiation.
However, UV radiation can also lead to photochemical reactions, the photochemical reaction products then intervening in skin and cell metabolism.
Such photochemical reaction products are chiefly free radical compounds, for example hydroxyl radicals, hydroperoxy radicals and superoxide ions. Undefined free radical photo-products which are formed in the skin itself can display uncontrolled secondary reactions because of their high reactivity. However, even singlet oxygen, an excited state of the oxygen molecule which is not in free radical form, can occur with UV irradiation, as can short-lived epoxides and many others. Singlet oxygen, for example, is distinguished from the triplet oxygen usually present (free radical base state) by an increased reactivity. Nevertheless, excited, reactive (free radical) triplet states of the oxygen molecule also exist.
To prevent these reactions, antioxidants and/or agents which trap the radicals can additionally be incorporated into the cosmetic or dermatological formulations.
Most inorganic pigments which are known to be used in cosmetics to protect the skin from UV rays are UV absorbers or UV reflectors. These are oxides of titanium, zinc, iron, zirconium, silicon, manganese, aluminium, cerium and mixtures thereof, as well as modifications.
Although there are cosmetic and dermatological formulations which are entirely advantageous for protecting the skin against the damaging consequences of the action of UV light, one disadvantage which is often obs
REFERENCES:
patent: 5207998 (1993-05-01), Robinson et al.
Gers-Barlag Heinrich
Hachmann Stefan
Nissen Bente
Schultz Sabine
Beiersdorf AG
Dodson Shelley A.
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