Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
1999-12-08
2002-04-09
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S401000, C424S489000, C424S490000, C424S497000
Reexamination Certificate
active
06368577
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to nanoparticles and more particularly to the use of nanoscale UV filters in cosmetics.
UV filters (also known as protection factors) are organic substances which are capable of absorbing ultraviolet radiation and releasing the energy absorbed in the form of longer-wave radiation, for example heat. Substances of this kind are known in large numbers from the prior art and are used in particular in sunscreens and in other cosmetic products for hair care and body care to counteract the harmful effects of the sun such as, for example, erythemas, hyperkeratoses, skin ageing and, in the worst case, skin cancer. A corresponding overview of suitable UV filters was published by P. Finkel in SÖFW-Journal 122, 543 (1996); the use of nanoscale inorganic UV-blocking pigments is discussed by C. Müller-Goymann et al. in Parf. Kosm. 79, 24 (1998). So far as the consumer is concerned, there is an obvious need for effective sun protection, i.e. as long an exposure time as possible, which generally requires a particularly high percentage content of light filters in the formulation. To the manufacturer of such products, this represents a twofold problem because relatively large quantities of UV filters are difficult to incorporate in stable emulsions and, in addition, add significantly to their cost.
Accordingly, the problem addressed by the present invention was to improve the effectiveness of organic, preferably crystalline, topically applied UV filters by presenting them in new forms. At the same time, a way was to found of producing UV filter emulsions, particularly w/o emulsions, with a high content of UV filters in storage-stable form.
DESCRIPTION OF THE INVENTION
The present invention relates to the use of nanoscale organic UV filters with particle diameters of 10 to 300 nm for the production of cosmetic and/or pharmaceutical preparations.
It has surprisingly been found that the effectiveness of organic light filters can be significantly increased if they are present in the form of nanoparticles, i.e. particles with a mean diameter of 10 to 300 and preferably 50 to 150 nm. Accordingly, the quantity used can be reduced for the same sun protection effect. In addition, the effect of coating the particles with protective colloids is not only the absence of subsequent agglomeration, it also prevents any unwanted penetration of the nanofilters into the skin. In addition, the particle fineness of the filters even enables stable w/o emulsions with high light filter contents to be produced.
Organic UV filters
Nanoscale UV filters which may be used in accordance with the invention are, for example, organic substances which are liquid or solid, but preferably crystalline at room temperature and which are capable of absorbing ultraviolet radiation and of releasing the energy absorbed in the form of longer-wave radiation, for example heat. UV-B filters can be oil-soluble or water-soluble. The following are examples of oil-soluble substances:
3-benzylidene camphor or 3-benzylidene norcamphor and derivatives thereof, for example 3-(4-methylbenzylidene)-camphor as described in EP-B1 0693471;
4-aminobenzoic acid derivatives, preferably 4-(dimethylamino)-benzoic acid-2-ethylhexyl ester, 4-(dimethylamino)-benzoic acid-2-octyl ester and 4-(dimethylamino)-benzoic acid amyl ester;
esters of cinnamic acid, preferably 4-methoxycinnamic acid-2-ethylhexyl ester, 4-methoxycinnamic acid propyl ester, 4-methoxycinnamic acid isoamyl ester, 2-cyano-3,3-phenylcinnamic acid-2-ethylhexyl ester (Octocrylene);
esters of salicylic acid, preferably salicylic acid-2-ethylhexyl ester, salicylic acid-4-isopropylbenzyl ester, salicylic acid homomenthyl ester;
derivatives of benzophenone, preferably 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4′-methylbenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone;
esters of benzalmalonic acid, preferably 4-methoxybenzalmalonic acid di-2-ethylhexyl ester;
triazine derivatives such as, for example, 2,4,6-trianilino-(p-carbo-2′-ethyl-1′-hexyloxy)-1,3,5-triazine and Octyl Triazone as described in EP-A1 0818450;
propane-1,3-diones such as, for example, 1-(4-tert.butylphenyl)-3-(4′-methoxyphenyl)-propane-1,3-dione;
ketotricyclo(5.2.1.0)decane derivatives as described in EP-B1 0694521.
Suitable water-soluble substances are
2-phenylbenzimidazole-5-sulfonic acid and alkali metal, alkaline earth metal, ammonium, alkylammonium, alkanolammonium and glucammonium salts thereof;
sulfonic acid derivatives of benzophenones, preferably 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and salts thereof;
sulfonic acid derivatives of 3-benzylidene camphor such as, for example, 4-(2-oxo-3-bornylidenemethyl)-benzene sulfonic acid and 2-methyl-5-(2-oxo-3-bornylidene)-sulfonic acid and salts thereof.
Typical UV-A filters are, in particular, derivatives of benzoyl methane such as, for example, 1-(4′-tert.butylphenyl)-3-(4′-methoxyphenyl)-propane-1,3-dione, 4-tert.butyl-4′-methoxydibenzoyl methane (Parsol 1789) or 1-phenyl-3-(4′-isopropylphenyl)-propane-1,3-dione. The UV-A and UV-B filters may of course also be used in the form of mixtures. According to the invention, it is preferred to use light filters which are solid and, in particular, crystalline at room temperature because they can readily be converted into nanoscale solid particles. However, filters liquid at room temperature may also be used. In this case, however, it is advisable to embed the nanoscale particles in a solid protective colloid matrix or to disperse them in a liquid carrier, for example a cosmetic oil, i.e. to prepare a nanodispersion.
Production of Nanoparticles
One such process for the production of nanoparticles by rapid expansion of supercritical solutions (RESS) is known from the article by S. Chihlar, M. Türk and K. Schaber in Proceedings World Congress on Particle Technology 3, Brighton, 1998. To prevent the nanoparticles from agglomerating, it is advisable to dissolve the starting materials in the presence of suitable protective colloids or emulsifiers and/or to expand the critical solutions into aqueous and/or alcoholic solutions of the protective colloids or emulsifiers or into cosmetic oils which may in turn contain redissolved emulsifiers and/or protective colloids. Suitable protective colloids are, for example, gelatine, casein, chitosan, gum arabic, lysalbinic acid, starch and polymers, such as polyvinyl alcohols, polyvinyl pyrrolidones, polyalkylene glycols and polyacrylates. Accordingly, the nanoscale organic UV filters preferably used are those which are surrounded by a protective colloid and/or an emulsifier. The protective colloids or emulsifiers are normally used in quantities of 0.1 to 20% by weight and preferably in quantities of 5 to 15% by weight, based on the UV filters.
Another suitable process for the production of nanoscale particles is the evaporation technique. Here, the starting materials are first dissolved in a suitable organic solvent (for example alkanes, vegetable oils, ethers, esters, ketones, acetals and the like). The resulting solutions are then introduced into water or another non-solvent, optionally in the presence of a surface-active compound dissolved therein, in such a way that the nanoparticles are precipitated by the homogenization of the two immiscible solvents, the organic solvent preferably evaporating. O/w emulsions or o/w microemulsions may be used instead of an aqueous solution. The emulsifiers and protective colloids mentioned at the beginning may be used as the surface-active compounds. Another method for the production of nanoparticles is the so-called GAS process (gas anti-solvent recrystallization). This process uses a highly compressed gas or supercritical fluid (for example carbon dioxide) as non-solvent for the crystallization of dissolved substances. The compressed gas phase is introduced into the primary solution of the starting materials and absorbed therein so that there is an increase in the liquid volume and a reduction in solubility and fine particles are pre
Dolhaine Hans
Fabry Bernd
Foerster Thomas
Kropf Christian
Cognis Deutschland GmbH
Dees Jose′ G.
Drach John E.
George Konata M.
Trzaska Steve J.
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