Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1998-04-20
1999-11-09
Dodson, Shelley A.
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424 60, 424401, 424489, 514844, 514937, 514944, 514951, A61K 742, A61K 744, A61K 700, A61K 914
Patent
active
059808721
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for producing new formulations of UV absorbers and to their use in sunscreen compositions which, in turn, are useful, in particular, for the protection of human skin.
It has long been known that prolonged exposure to that 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 aging.
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 zinc oxide and 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 ("Redox Mechanisms in Heterogeneous Photocatalysis", Serpone et al, Electrochemistry in Colloids and Dispersions, Editors Mackay and Texter, VCH Publishers Inc., New York 1992).
Micronized, insoluble organic UV absorbers, 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, micronized, insoluble organic UV absorbers show no tendency, under the influence of light, to generate radicals which could damage or sensitise human skin.
Accordingly, the present invention provides, as a first aspect, a method of producing a composition, which is especially suitable for use in pharmaceutical or cosmetic applications, comprising a micronised insoluble organic UV absorber, which method comprises grinding the insoluble 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 insoluble organic UV absorber, of an alkyl polyglucoside having the formula C.sub.n H.sub.2n+1 O(C.sub.6 H.sub.10 O.sub.5).sub.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.sub.6 H.sub.10 O.sub.5) and ranges from 1.4 to 1.6, or an ester thereof.
The insoluble organic UV absorber may be, e.g., an oxanilide, a triazine, a triazole, a vinyl group-containing amide, a cinnamic acid amide or a sulfonated benzimidazole UV absorber.
One preferred class of oxanilide UV absorbers is that having the formula: ##STR1## in which R.sub.1 and R.sub.2, independently, are C.sub.1 -C.sub.18 alkyl or C.sub.1 -C.sub.18 alkoxy. A preferred compound of formula (1) is N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-ethanediamide.
A preferred class of triazine compounds is that having the formula: ##STR2## in which R.sub.3, R.sub.4 and R.sub.5, independently, are H, OH, C.sub.1 -C.sub.18 alkoxy, NH.sub.2, NH--R.sub.6 or N(R.sub.6).sub.2 in which R.sub.6 is C.sub.1 -C.sub.18 alkyl, OR.sub.6 in which R.sub.6 has its previous significance, phenyl, phenoxy or anilino, or pyrrole, 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.sub.2, C.sub.1 -C.sub.18 alkyl or -alkoxy, C.sub.1 -C.sub.18 carboxyalkyl, C.sub.5 -C.sub.8 cycloalkyl, a methylidenecamphor group, a group --(CH.
REFERENCES:
patent: 4617390 (1986-10-01), Hoppe et al.
patent: 5631215 (1997-05-01), Kinsman
Electro Chemistry in Colloids and Dispersion, 399ff.
Luther Helmut
Minklei Marina
Stehlin Albert
Ciba Specialty Chemicals Corporation
Dodson Shelley A.
Hall Luther A. R.
Lamm Marina
Mansfield Kevin T.
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