UV-protection formulation

Details UV-protection formulation UV-protection formulation

1998-07-24

2001-05-22

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S060000, C424S401000, C424S487000, C514S937000

Reexamination Certificate

active

06235271

ABSTRACT:

The present invention relates to new formulations and, in particular, to new UV-protection formulations which comprise a combination of a micronised UV absorber and one, or preferably both of i) an oil-soluble, non-micronised UV absorber and/or an inorganic micropigment and ii) a polymeric hollow sphere additive and/or a polymer selected from xanthan and/or polyvinylpyrrolidone. The new combinations exhibit an unexpected synergistic sun protection effect. This synergistic effect is greatly enhanced when the micronised UV absorber and the oil-soluble, non-micronised UV absorber and/or an inorganic micropigment are used in combination with a polymeric hollow sphere additive and/or a polymer selected from xanthan and/or polyvinylpyrrolidone.
It has long been known that prolonged exposure to UV radiation which reaches the surface of the earth can lead to the formation of erythemas or light dermatoses, as well as to an increased incidence of skin cancers, or accelerated skin ageing.
Various sunscreen formulations have been proposed which include a material which is intended to counteract UV radiation, thereby inhibiting the said undesired effects on the skin.
A great number of compounds has been proposed for use as UV protectants in sunscreen formulations, especially soluble organic UV absorbers and insoluble micronised inorganic compounds, in particular zinc oxide and titanium dioxide.
With respect to the use in sunscreen formulations of soluble organic UV absorbers, they have the disadvantages that their effectiveness as UV protectants in terms of SPF (Sun Protection Factor) in a sunscreen formulation is often too low for commercial purposes; as a result of their solubility, they exhibit relatively high allergenic potential; and that as a result of intrinsic photochemical lability, the duration of the protective effect is often too low.
The high specific weight of insoluble inorganic compounds, such as titanium dioxide leads to a reduced stability of formulations containing them. Moreover, such inorganic compounds have been claimed to generate toxic radicals under the influence of light and water (“Redox Mechanisms in Heterogeneous Photocatalysis”, Serpone et al, Electrochemistry in Colloids and Dispersions, Editors Mackay and Texter, VCH Publishers Inc., New York 1992).
In GB-A-2303549, there is described a method of producing micronised, insoluble organic UV absorbers, as well as a sunscreen composition comprising a) 0.1 to 15%, preferably 0.5 to 10% by weight, based on the total composition of a micronised formulation of an insoluble organic UV absorber, produced according to the said method; and optionally b) a cosmetically acceptable carrier. Micronised, insoluble organic UV absorbers so obtained, when used in sunscreen formulations, provide excellent UV protection and have at least as high an SPF rating as corresponding sunscreen formulations containing a known inorganic UV absorber. Unlike the latter UV absorbers, micronised, insoluble organic UV absorbers show no tendency, under the influence of light, to generate radicals which could damage or sensitise human skin.
In a further development of the concept disclosed in GB-A-2303549, it has now been found that when a micronised organic UV absorber is used in combination with one, or preferably both of i) an oil-soluble, non-micronised UV absorber and/or an inorganic micropigment and ii) a polymeric hollow sphere additive and/or a polymer selected from xanthan and/or polyvinylpyrrolidone, this combination exhibits an unexpected synergistic sun protection effect. This synergistic effect is greatly enhanced when the micronised UV absorber, or the soluble, non-micronised UV absorber are used individually, or preferably in combination together, with a polymeric hollow sphere additive.
Accordingly, the present invention provides, as a first aspect, a sun protection agent, which is especially suitable for use in pharmaceutical or cosmetic applications, comprising
a) a micronised organic UV absorber; and one, or preferably both of;
b) an oil-soluble, non-micronised UV absorber and/or an inorganic micropigment; and
c) a polymeric hollow sphere additive and/or a polymer selected from xanthan and/or polyvinylpyrrolidone.
The relative proportions of components a):b) and/or c) preferably range from 20:80 to 80:20, especially from 40:60 to 60:40, by weight.
The micronised organic UV absorber, component a), is preferably produced by the method described in GB-A-2303549, namely by a process which comprises grinding an organic UV absorber, in coarse particle form, in a grinding apparatus, in the presence of 1 to 50%, preferably 5 to 40% by weight, based on the micronised organic UV absorber, of an alkyl polyglucoside having the formula C
n
H
2n+1
O(C
6
H
10
O
5
)
x
H, in which n is an integer ranging from 8 to 16 and x is the mean polymerisation level of the glucoside moiety (C
6
H
10
O
5
) and ranges from 1.4 to 1.6, or an ester thereof.
The grinding apparatus used to produce the micronised organic UV absorber may be, e.g., a jet, ball, vibration or hammer mill, preferably a high speed stirring mill or impact mill, especially a rotating ball mill, vibrating mill, tube mill or rod mill.
The alkyl polyglucoside may consist of a C
1
-C
12
ester of the compound of formula C
n
H
2n+1
O(C
6
H
10
O
5
)
x
H, namely an ester formed by reacting a C
1
-C
12
acid, such formic, acetic, propionic, butyric, sulfosuccinic, citric or tartaric acid, with one or more free OH groups on the glucoside moiety (C
6
H
10
O
5
).
The micronised organic UV absorber may be, e.g., a triazine, a benzotriazole, a vinyl group-containing amide, a cinnamic acid amide or a sulfonated benzimidazole UV absorber.
A preferred class of triazine compounds is that having the formula
in which R
1
, R
2
and R
3
, independently, are H, OH, C
1
-C
3
alkoxy, NH
2
, NH—R
4
or N(R
4
)
2
in which R
4
is C
1
-C
3
alkyl, OR
4
in which R
4
has its previous significance, phenyl, phenoxy or anilino, or pyrrolo, in which the respective phenyl, phenoxy or anilino, or pyrrolo moieties are optionally substituted by one, two or three substitutents selected from OH, carboxy, CO—NH
2
, C
1
-C
3
alkyl or -alkoxy, C
2
-C
4
carboxyalkyl, C
5
-C
8
cycloalkyl, a methylidenecamphor group, a group —(CH═CH)
m
C(═O)—OR
4
in which m is 0 or 1 and R
4
has its previous significance, or a group
or the corresponding alkali metal, ammonium, mono-, di- or tri-C
1
-C
4
alkylammonium, mono-, di- or tri-C
2
-C
4
alkanolammonium salts, or the C
1
-C
3
alkyl esters thereof.
Preferred compounds of formula (1) are those having one of the formulae
as well as 2,4,6-tris(diisobutyl-4′-aminobenzalmalonate)-s-triazine and 2,4-bis(diisobutyl-4-aminobenzalmalonate)-6-(4′-aminobenzylidenecamphor)-s-triazine.
Particularly preferred compounds of formula (1) are those having the formula
in which the individual radicals R
5
are the same or different and each is hydrogen; an alkali metal; an ammonium group N(R
6
)
4
in which R
6
is hydrogen or an organic radical; C
1
-C
3
alkyl; or a polyoxyethylene radical which contains from 1 to 10 ethylene oxide units and the terminal OH group of which may be etherified by a C
1
-C
3
alcohol.
In relation to the compounds of formula (24), when R
5
is an alkali metal it is preferably potassium or, especially sodium; when R
5
is a group N(R
6
)
4
in which R
6
has its previous significance, it is preferably a mono-, di- or tri-C
1
-C
4
alkylammonium salt, a mono-, di- or tri-C
2
-C
4
alkanolammonium salt or a C
1
-C
3
alkyl ester thereof; when R
6
is a C
1
-C
3
alkyl group, it is preferably a C
1
-C
2
alkyl group, more preferably a methyl group; and when R
6
is polyoxyethylene group, this preferably contains from 2-6 ethylene oxide units.
One preferred class of triazole micronised organic UV absorbers is that having the formula
in which T
1
is C
1
-C
3
alkyl or, preferably, hydrogen; and T
2
is C
1
-C
4
alkyl, preferably t-butyl, or C
1
-C
4
alkyl substituted by phenyl, preferably &agr;,&agr;-dimethylbenzyl.
A further preferred class of triazol

Affiliated with

Also associated with

Rating

UV-protection formulation does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with UV-protection formulation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and UV-protection formulation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2549345