COSMETIC FORMULATION

Abstract: A degreasing or moisturising composition contains silanised silica gel, a humectant such as glycerine, and an inert carrier. The composition is used to treat sebhorreic conditions without causing dry skin.

Description: The present invention relates to the use of silanised silica gel in particular antiseborrheic compositions. Silanised silica gel is a known adsorbent and may be produced either by a) treating fine particles of silica gel with a reactive silane thereby replacing many of the hydroxy groups with substituted siloxy groups, or b) polymerising a suitable siloxane monomer in the presence of fine particles of silica gel thereby coating the particles with a polysiloxane. Reactive silanes useful in method (a) above include alkyl, aryl especially phenyl and aralkyl especially benzyl halosilanes and -silazanes and alkyl, aryl especially phenyl and aralkyl especially benzyl alkoxysilanes and -silazanes. Particular examples of such silanes include dimethyl monochlorosilane dimethyl dichlorosilane trimethylchlorosilane hexamethyl disilazane trichloro-octadecylsilane Suitable siloxane monomers for use in method (b) above include hydrogen polysiloxane such as methyl hydrogen polysiloxane and alkyl, aryl and aralkyl cyclotetrasiloxanes, especially octamethylcyclotetrasiloxane. Polymerisation may be effected by heating or chemical catalysis. Similar techniques may be applied to produce silanised alumina, calcium carbonate, hydroxyapatite, iron oxide mica, talc and derivatives thereof including titanated mica and talc. Method (a) above is suitable for silanising adsorbents having free hydroxyl groups, method (b) may be applied to most finely divided solids to produce a silanised adsorbent. As used herein the terms 'seborrhea' and 'seborrheic conditions' refer to a range of conditions from simple cosmetic 'greasy' skin and hair to clinical seborrhea which is often associated with pimpling or acne including dry acne. In all cases of seborrhea a major contributory factor is excessive secretion of sebum which accumulates in and on the stratum corneum and hair and/or sebaceous follicles. Some contribution to the abnormally high lipid accumulation comes from the lipids exuded from differenciating skin cells. The use of silanised adsorbents is effective in all seborrheic conditions. It is believed that silanised silica gel not only removes the surface lipid but also drains the sebum from the lipid reservoirs in the stratum corneum and sebaceous follicles. The latter effect is important since by draining the reservoirs of sebum the rate of regreasing of the skin surface may be reduced with commensurate improvement in the appearance of the skin. Silanised silica gel also has an instant cosmetic matting effect thereby immediately improving the appearance of greasy skin. As they do not adsorb water, they do not have a tendency to cake and they remain effective despite perspiration and high ambient humidity. We have now found that particular formulations of silanised silica gel can provide both a degreasing effect and, at the same time, a moisturising effect thus enabling the treatment of sebhorreic conditions without causing dry skin conditions. Accordingly the present invention provides a degreasing or moisturising composition comprising from 0.1 to 5% by weight silanised silica gel and 2.5 to 15% by weight of a humectant moisturising agent and an inert carrier or diluent therefor. Suitably the silanised silica gel, has a mean particle size of 0.1 to 20 x 10⁻⁶m, the 'particles' consisting of aggregates of very fine 'primary particles' of much smaller size. Suitable humectant moisturising agents include sorbitol, propylene glycol, glycerine and 'Lubragel®'. ('Lubragel' is a proprietary material comprising a clathrate formed by reacting sodium glycerate and an acrylic acid polymer). Preferred humectant moisturisers are glycerine and Lubrajel. With silanised silica gel, a white deposit may be left if the composition contains over 2.5% by weight of the silanised silica gel and preferably this material is included at from 0.25 to 2.5% by weight, more preferably at 0.5% by weight. Suitably the composition comprises from 2.5 to 15% by weight of humectant moisturising agent, more preferably from 5 to 10% by weight. The composition may also comprise optional accessory ingredients such as suspending agents, perfume, colouring and preserving agents, pigments, keratolytics, antibacterials and antimicrobial agents such as Irgasan or chlorhexidine. Examples of suspending agents include polyacrylic acid, carbomers, hydroxyalkyl cellulose, Xanthan gum and magnesium aluminium silicate. Preferably a lower alkanol such as isopropanol or ethanol is included in any of the aforementioned compositions at from 5 to 40% w/w, more preferably at about 10% w/w to impart astringency and a cooling effect. Ethanol is preferred. The compositions may be presented as conventional cosmetic formulations such as aqueous lotions or aqueous emulsions. Particularly suitable presentations include a cleansing lotion having an aqueous base and a treatment cream or lotion comprising respectively a water in solvent or solvent in water emulsion. In such emulsion presentations it is advantageous that the solvent should be volatile, thus after application the solvent evaporates rather than leaving an oily deposit on the skin. Suitable materials for use as solvents in these emulsions include isoparaffins, linear and cyclic polysiloxanes especially linear polydimethylsiloxanes and cyclomethicone. These may be included in the compositions at from 5 to 25% by weight, preferably at 10 to 20% by weight. The diluent or carrier is usually water or a water/solvent emulsion. Suitably the compositions comprise 60 to 80% by weight of water. The compositions are applied to the skin as required. The cleansing lotions mentioned above would typically be used twice a day whereas the treatment creams and lotions are suitably formulated as 'leave-on' products and would be applied once a day usually in the evening, then removed by washing in the morning. The compositions of the invention may be prepared by admixing the ingredients at a temperature of from 0 to 100 o C and substantially atmospheric pressure, with optional heating within that temperature range to enable optimum mixing to occur. The following Examples illustrate the invention. Example 1 Cleansing lotion This may be applied directly using a cotton-wool swab or may be impregnated into tissue-wipes. Example 2 % w/w a) Cyclomethicone/Dimethicone polyol 10 Cyclomethicone 10 Sodium Chloride 2 Silanised silica 0.5 Ethanol 10 Lubrajel 5 Deionised water 62.5 % w/w b) P.E.G. 22/Dodecyl glycol copolymer 1 Cyclomethicone 10 Silanised silica 0.5 Ethanol 10 Glycerine 5 Deionised water 73.5 % w/w c) Glyceryl oleate 1 Cyclomethicone 20 Silanised silica 0.5 Ethanol 10 Lubragel® 5 Deionised water 63.5 Example 3 Solvent in Water Lotions % w/w a) Stearic acid 3 Cyclomethicone 10 Ethanol 10 Triethanolamine 1 Silanised silica 0.5 Deionised water 70.5 Glycerine 5 % w/w b) Sorbitan stearate 1.5 Polysorbate 60 2 Cyclomethicone 10 Ethanol 10 Silanised silica 0.5 Deionised water 71 Glycerine 5 % w/w c) Hydrogenated Tallow Glyceride Citrate 1.5 Glyceryl palmitate lactate 0.75 Cyclomethicone 10 Ethanol 10 Silanised silica 0.5 Deionised water 72.25 Glycerine 5

Claims: A degreasing or moisturising composition comprising from 0.1 to 5% by weight silanised silica gel and from 2.5 to 15% by weight of a humectant moisturising agent, and an inert carrier or diluent therefor. A composition according to claim 1, in which the silica gel has a mean particle size of from 0.1 to 20 x 10⁻⁶m. A composition according to claim 1 or 2, in which the humectant comprises sorbitol, propylene glycol, glycerine or Lubragel®. A composition according to any one of claims 1 to 3, containing from 5 to 40% w/w of lower alkanol.

Inventors: DUTTON, SUSAN, ELLIOTT, THOMAS JOSEPH
Applicants: BEECHAM GROUP PLC
Application year: 1985
Main classification: A61K7
IPC codes: A61K47, A61K8, A61Q19