Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1998-01-28
1999-09-14
Dodson, Shelley A.
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424 60, 424401, A61K 742, A61K 744, A61K 700
Patent
active
059519673
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a new multi-phase sunscreen agent with improved sunscreen properties.
2. The Prior Art
A multitude of sunscreen formulations are already known that contain certain organic and inorganic active ingredients as emulsions for filtering out (absorption or reflection) UVB radiation (range 290 to 320 nm) and UVA radiation (range 320 to 400 nm). Known organic active ingredients include in particular the derivatives of dibenzoylmethane, benzophenone, salicylic acid, cinnamic acid, 3-benzylidenecamphor, 4-aminobenzoic acid, etc. Known inorganic active ingredients include pigments such as the oxides of titanium, iron, zinc, silicon, aluminum, zirconium, etc. A mixture of organic and inorganic substances that is described as being superior to titanium dioxide is also known (European Patent EP A 588,498).
Published International Application No. WO 94/22419 describes a skin tanning agent where two components are present in separate containers and react when mixed together on the skin, producing a color.
The development of sunscreen formulations has mainly tended toward new active ingredients or a combination of known active ingredients. In general, these are present in emulsions to ensure a good and uniform distribution on the skin, where agglomerations of inorganic pigments have been prevented by surface-active substances.
However, hydrodispersions have also become known that do not contain any emulsifier and are a dispersion of a discontinuous lipid phase (liquid, solid or semisolid) in an external continuous (aqueous) phase. The stability of such an emulsifier-free system is achieved, for example, by creating a gel structure in the aqueous phase with a stable suspension of the lipid droplets in this gel structure. A disadvantage of these hydrodispersions is the required high concentration of UV filter materials and their stickiness.
European Patent EP A 603,080 describes a cosmetic or dermatological two-phase composition that consists of an aqueous phase and a separate oil phase containing alkyldimethylbenzyl-ammonium chloride in the aqueous phase and is suitable for skin care or for removing make-up.
World Patent WO 94/17779 discloses hydrodispersions which are emulsifier-free products to prevent possible irritating effects of emulsifiers (Mallorca acne). The stability of the dispersions is supposed to be ensured by an internal lipid phase with the inorganic pigments and an external aqueous phase.
SUMMARY OF THE INVENTION
The object of this invention is to achieve an improvement in the sunscreen properties through a particular arrangement of these agents in a formulation system and to prevent the chemical filters from coming directly in contact with the skin.
According to this invention, the new sunscreen consists of at least two separate and essentially liquid phases, where UVA and/or UVB filters and/or UVC filters (hereinafter: UV filters) are present in at least two separate phases, where the phases separate spontaneously after a brief and gentle mixing process, leaving the respective UV filters in the phase in which they were originally present.
It has been found that by spreading one of the separate phases on the skin and applying at least one second phase above it, where the second phase essentially does not mix with the first phase and each phase contains a UV filter, improved absorption of UV radiation is achieved in comparison with an emulsion or hydrodispersion containing the same amount of these UV filters. When converted to a sunscreen factor, this means an increase by at least two stages, preferably four to ten stages.
However, an improvement in the sunscreen factor is achieved even if only one phase contains a UV filter and the other phase does not contain any UV filter but contains different substances from the first phase, because the depth of penetration and the refraction of incident radiation differ according to the thickness of the layer and possibly the type of layer.
The sunscreen agent according to this invention
REFERENCES:
patent: 5213799 (1993-05-01), Goring et al.
patent: 5468496 (1995-11-01), Touzan et al.
Ferrero Louis
Gerbron Jacques
Golz Karin
Stanzl Klaus
Zastrow Leonhard
Dodson Shelley A.
Lamm Marina
Lancaster Group GmbH
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