Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2001-11-07
2004-01-06
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
06673336
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a conjugate, which can be used for the preparation of dermatological and cosmetic compositions. The invention also relates to processes for preparing such conjugate and to its use.
2. Related Art
Dermatological or cosmetic compositions are used for example to protect the skin against harmful external effects, such as against sun radiation. In modern society a more or less marked tanning of skin is considered to be attractive and an expression of dynamics and sportiveness. Besides this desired effect of sun on skin also a series of undesired side effects is occurring such as sunburn or premature aging of skin and wrinkling. Meanwhile a number of efficient UV filters has been developed which, applied onto the skin in the form of creams, lotions or gels can inhibit effectively the development of sunburn even under a more intensive exposure to sun. The UV filters contained in the pharmaceutical or cosmetic preparations form a film and a layer, respectively, on the surface of the skin. The known UV filters and sun protecting agents act in such manner that they absorb certain parts of sunlight so that this radiation cannot penetrate into deeper layers of the skin. It is known that the most dangerous part of the sun radiation is formed by the ultraviolet rays having a wavelength of less than 400 nm. The lower limit of the ultraviolet rays which reach the surface of earth by the absorption in the ozone layer is restricted to about 280 nm. The sun filter commonly used in the cosmetics absorb in a wavelength range of from 280 to 400 nm. This range comprises UVB rays having a wavelength between 280 and 320 nm which play a decisive roll in the formation of a sun erythema, as well as UVA rays having a wavelength between 320 and 400 nm which cause tanning but also aging of skin, promote the initiation of an erythematic reaction or increase this reaction with certain individuals or even may initiate phototoxic or photoallergic and irritative reactions.
Light protection formulations which have been applied onto the skin have the purpose to hold back skin damaging parts of radiation. As light filters inorganic or organic materials can be used.
Light protection formulations based on organic light filters contain organic light filters which are soluble in water and/or oil or are soluble neither in water nor in oil.
Light protection formulations having insoluble particulate organic light filters are described for example in WO 97/3643. The group of insoluble organic light filters is, however, restricted to a few classes of compounds.
Light protection formulations having organic light filters and being soluble in water and/or oil are described in publications DE-A-197 46 654, DE-A-197 55 504, EP-A-709 080, EP-A-775 698, EP-A-893 119 and U.S. Pat. No. 5,882,632.
In DE-A-197 46 654 the use of 4,4-diaryl-butadiene derivatives as soluble organic light filter in light protection formulations for protecting skin against UVA radiation is described.
The above mentioned light protection formulations must contain the organic light filters in a high concentration in order to ensure a sufficient light protection. However, the most serious disadvantage of organic soluble light filters consists in that optionally they penetrate into the skin due to their solubility and can cause skin damages or allergies.
In JP-A-11-255 630 a light protection formulation for protecting the skin against UVA radiation is described which contains a dibenzoyl methane derivative and is applied to a silicone polymer-coated inorganic support. However, the preparation of this light protection formulation is troublesome and time consuming due to a multitude of operations. Furthermore, dibenzoyl methane derivatives are not photostable (light-resistant).
Dermatological and cosmetic compositions can further contain a multitude of active substances, such as organic substances having antioxidative and/or radical inhibiting properties as well as repellants.
In general, a heterogenisation of the active substances contained in dermatological and cosmetic compositions is desirable, since i.a. a penetration into the skin and a possibly resulting skin damage or allergy can be prevented.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a conjugate based on organic active substances and which cannot penetrate into the skin.
This object is achieved according to the present invention by providing a conjugate which comprises an inorganic pigment and an active substance based on organic compounds, the active substance being covalently bound through a spacer group to the inorganic pigment. The conjugate of the invention is characterized in that the spacer group contains an element of the groups 3A, 4A, 3B, 4B, 5B and 6B of the periodic table of elements.
The invention also provides a dermatological or cosmetic composition comprising at least one conjugate of the above mentioned type and at least one cosmetically, pharmaceutically and/or dermatologically compatible vehicle and/or adjuvant.
In the frame of the present invention the expression “conjugate” means a product which is obtained by a molecular i.e. covalent bond between the active substance and the inorganic pigment. The expression “active substance” comprises for example light absorbing organic compounds, substances having antioxidative and/or radical inhibiting properties, repellants, preservatives and derivatives of these active substances which can be bound covalently through a spacer group to an inorganic pigment. The active substance or derivative thereof comprises preferably a nucleophilic group. It is preferred that the active substance per se, i.e. without being bound to an inorganic pigment, is water soluble and/or oil soluble.
The conjugate of the invention contains an inorganic pigment. In the frame of the present invention the expression “pigment” means a dye (colorant) or filler being insoluble in the application medium. The inorganic pigment in the conjugate of the invention preferably is a metal oxide or a semi-metal oxide.
Examples of inorganic pigments comprise oxides, silicates, phosphates, carbonates, sulfates and nitrides, oxides being preferably used.
Preferred inorganic pigments comprise magnesium oxide, aluminum oxide, silicon dioxide, zinc oxide, cerium oxide, titanium dioxide, zirconium oxide, manganese oxide, boron oxide, red or black iron oxide, tale, kaolin, natural and synthetic mica materials, such as muscovite, phlogopite, lepidolite, biotite and vermiculite, magnesium carbonate, calcium carbonate, aluminum silicate, barium silicate, calcium silicate, magnesium silicate, strontium silicate, barium sulfate, calcium sulfate, calcium phosphate, fluoroapatite, hydroxyapatite, ceramic powder, boron nitride, iron titanate, zeolite and mixtures thereof. Silicon dioxide, titanium dioxide, mica, talc and mixtures of the above mentioned pigments (in the following called “mixed pigments”) such as silicon dioxide/titanium dioxide are particularly preferably used.
Commercially available inorganic mixed pigments which can be used according to the invention comprise mixtures of titanium dioxide/mica, titanium dioxide/mica/tin oxide, titanium dioxide/mica/iron oxides, titanium dioxide/mica/silicon dioxide, titanium dioxide/mica/carmine, mica/iron oxides/aluminum oxide, mica/iron oxides, titanium dioxide/mica/zinc oxide, titanium dioxide/mica/barium sulfate, mica/silicon dioxide and titanium dioxide/iron oxides/silicon dioxide. These mixed pigments are sold under the names Timiron®, Soloron®, Colorona®, Dichrona®, Microna®, Micronaspher® and Ronaspher®.
Light scattering pigments such as Ronaspher® LDP as well as nacreous pigments can also be used.
The silicates can have a chain, belt or sheet-shaped structure. Silicates having a sheet-shaped structure such as mica or talc are preferably used.
The form in which the metal oder semi-metal compound is present, is not restricted to certain forms.
The metal or semi-metal compound has preferably the form of spherical particles. Suitable materials b
Anselmann Ralf
Buchholz Herwig
Kirschbaum Michael
Pflücker Frank
Poetsch Eike
Dodson Shelley A.
Jenkins & Wilson & Taylor, P.A.
Merck Patent GmbH
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