Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2002-02-25
2004-06-08
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
06746665
ABSTRACT:
DESCRIPTION
The present invention relates to a sun protection product with microparticles on the basis of water-insoluble linear polyglucan which, on the one hand, ensures good UV protection and appears transparent upon application.
Known sun protection products comprise inter alia pigments, such as, for example, titanium dioxide and zinc oxide as such or in the form of “micronized particles” as light protection filters. From a cosmetics viewpoint, these pigments have the disadvantage that they whiten, i.e. make the skin appear white in colour.
As a compromise for reducing the whitening to a tolerable degree and nevertheless achieving an acceptable UV protection, these pigments are usually used with a comparatively small particle size between 10 and 100 nm (A. Schrader, M. Rohr “Auffälligkeiten bei der Entwicklung und Prufung von mikropigmenthaltigen Sonnenschutzformulierungen [Unusual features in the development and testing of sun protection formulations containing micropigments]” SÖW Journal, 124, pages 478-487, 8/98).
In addition, titanium dioxide is to be viewed critically from a health viewpoint. In a study using titanium dioxide which had been extracted from sun protection products, it was observed upon irradiation with sunlight that titanium dioxide is able to catalyze photooxidation and damages bacterial DNA (CTFA/TRN Volume 12, No. 3, page 5 (1998) with reference to FEBS Letters, 418, 87-90, 1997).
A light-protecting action is also known for individual polysaccharides. For example, a light-protecting action has been described for poly-&bgr;-1,3-glucans (H. Eggensperger, M. Wilker, “Multiaktiv wirksame Polysaccharide Teil I-Pilzextrakte und Teil II-Pflanzliche Polysaccharide [Multiactive polysaccharides part I-fungus extracts and part II-vegetable polysaccharides]” in SÖW Journal, 123, 8/97, pages 542-546 and 12/97, pages 838-842).
Poly-&bgr;-1,3-glucans which can be obtained from yeasts have a linear structure with a small proportion of &bgr;-1,6 branching.
It has also been proposed to use glycogen (a highly branched poly-1,4-&agr;-glucan with branching in the 6-position) obtained biotechnologically or from marine molluscs for sun protection products (M. Pauly, G. Pauly “New Polysaccharides Interest in Care Cosmetology” IN-COSMETICS 1997, Conference Proceedings, pages 417-444, Verlag für chemische Industrie, H. Ziolkowsky GmbH, 1998).
EP-B-0 487 000 proposes the use of a cosmetic composition in the form of an emulsion having 15 to 40% by weight of an enzymatically debranched starch in sun protection products, where the enzymatically degraded starch is a linear poly-1,4-&agr;-glucan having 15 to 65 anhydroglucose units. However, there is no reference to a potential light protection action of the enzymatically debranched starch used therein; instead, it is used as an emulsifying auxiliary.
In view of the risks of intensive UV exposure, there is a growing need for suitable sun protection filters which not only offer reliable protection, but also do not impair the external appearance and are thus also suitable for daily use.
According to the invention, this object is achieved by a sun protection product which comprises, as effective constituent, spherical microparticles which consist entirely or partially of at least one water-insoluble linear polyglucan.
The novel sun protection products with spherical microparticles which consist entirely or partially of at least one water-insoluble linear polyglucan can ensure excellent UV protection and in addition the microparticles appear transparent, even in high concentrations.
Moreover, the microparticles used according to the invention form stable suspensions or dispersions even without the addition of dispersion auxiliaries. This is advantageous in particular for the use in emulsion-based sun protection products since the addition of dispersion auxiliaries can be dispensed with or the amount thereof can be reduced, thus simplifying and reducing the cost of production.
In addition, the spherical microparticles convey a pleasant soft feel upon application, which is attributed to their regular structure.
For the sun protection products according to the invention, recourse may be had to the formulations and additives customary for such products. Particularly preferred bases for formulations are emulsions, such as, for example, O/W or W/O emulsions, aqueous or fat-containing gels, hydrogels, oils, emulsifier-free formulations, etc. The sun protection products can be used in the form of creams, lotions, sprays, fluids, powders, etc.
Apart from the microparticles, the sun protection products according to the invention can also comprise further known UV filters.
The proportion of the microparticles in the sun protection products according to the invention is governed by the base used. It may be up to 70% by weight, based on the total weight of the sun protection product, e.g. in wax-oil bases as are used inter alia for “sun protection cream compacts”. In general, amounts of from approximately 0.5 to about 20% by weight, preferably about 2 to about 15% by weight and in particular about 3 to about 10% by weight, suffice. An amount less than 0.5% by weight is of no importance for UV protection.
It goes without saying that the amount depends heavily on the composition of the product. If the sun protection product comprises further UV filters or if the base of the sun protection product is itself colored or pigmented, such as, for example, pigmented W/O or O/W emulsions, such that UV permeability is reduced from the outset, it is possible for smaller amounts of microparticles to be sufficient. For UV-permeable bases, e.g. transparent bases, such as, for example, unpigmented emulsions, oils or gels, it is advantageous to add larger amounts of microparticles.
The required amount can, however, be determined directly from case to case by a person skilled in the art with a few routine experiments.
The microparticles used for the sun protection products according to the invention can have an average diameter Dn (number-average) of 1 nm-100 &mgr;m, preferably 50 nm-10 &mgr;m, in particular 100 nm-3 &mgr;m and particularly preferably less than 1 &mgr;m, in particular less than 0.2 &mgr;m.
For the present invention, spherical microparticles are to be understood as meaning microparticles which have a virtually spherical shape. If a sphere is described by axes of identical length which start from a common origin and are directed into space and define the radius of the sphere in all spatial directions, the lengths of the axes may deviate from an ideal spherical state by from 1% to 40% for the spherical particles. The deviation is preferably 25% or less, particularly preferably 15% or less.
The spherical particles have a regular surface which can be compared macroscopically with a raspberry, where the depth of irregularities on the particle surface, such as recesses or indentations, is at most 20%, preferably 10%, of the average diameter of the spherical microparticles.
The specific surface area of the microparticles is generally from 1 m
2
/g to 100 m
2
/g, preferably 1.5 m
2
/g to 20 m
2
/g and particularly preferably 3 m
2
/g to 10 m
2
/g. Furthermore, the particles according to the invention preferably have a dispersity D=weight-average diameter (d
w
)
umber-average diameter (d
n
) of from 1.0 to 10.0, in particular from 1.5 to 5.0 and particularly preferably from 2.0 to 3.0.
The averages used herein are defined as follows:
d
n
=sum of n
i
×d
i
/sum of n
i
=number-average
d
w
=sum of n
i
×d
i
2
/sum of n
i
×d
i
=weight-average
n
i
=number of particles with diameter d
i
,
d
i
=a particular diameter,
i=serial parameter.
In this connection, the term weight indicates a weighted average, as a result of which the larger diameters are given greater importance.
The microparticles used according to the invention may also have been subjected to a surface modification by, for example, derivatizing functional groups, such as hydroxyl groups, of the polyglucans.
For t
Bengs Holger
Braunagel Alfred
Celanese Ventures GmbH
Dodson Shelley A.
Rosenman Katten Muchin Zavis
Sira Serge
Villacorta Gilberto M.
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