WO2006037665A1

WO2006037665A1 - Compact powder comprising polyamide particles containing an active agent

Info

Publication number: WO2006037665A1
Application number: PCT/EP2005/012031
Authority: WO
Inventors: Guillaume Cassin
Original assignee: L'oreal
Priority date: 2004-10-08
Filing date: 2005-09-23
Publication date: 2006-04-13

Abstract

The invention relates to an anhydrous cosmetic composition, especially in compact form, comprising: a pulverulent phase comprising polyamide particles; a fatty phase; and at least one moisture-sensitive cosmetic or pharmaceutical active agent, characterized in that the said particles have a mean volume diameter of less than or equal to 10 µm and contain at least a fraction of the active agent, and in that the fatty phase represents from 0.1% to 20% of the weight of the composition. The invention also relates to a cosmetic process for caring for greasy skin or for bleaching the skin, comprising the topical application to the skin of the abovementioned composition. The invention also relates to the use of this composition for the manufacture of a dermatological preparation for depigmenting the skin.

Description

Compact powder comprising polyamide particles containing an active agent

The present invention relates to an anhydrous cosmetic composition, especially in the form of a compact powder, comprising: a pulverulent phase comprising polyamide particles; a fatty phase; and at least one moisture-sensitive cosmetic or pharmaceutical active agent, characterized in that the said particles have a mean volume diameter of less than or equal to 10 μm and contain at least a fraction of the active agent, and in that the fatty phase represents from 0.1% to 20% by weight of the composition. The invention also relates to a cosmetic process for caring for greasy skin or for bleaching the skin, comprising the topical application to the skin of the abovementioned composition.

Compact care or makeup face powders are anhydrous compositions that generally comprise, on the one hand, a pulverulent phase especially comprising pigments and/or fillers (such ,as~polyamide particles) and, on the other hand, a fatty phase as binder comprising fatty substances, which is intended to give the finished product a certain density, to give the product softness and an emollient nature and to promote its adhesion to the skin. These compact powders are generally intended for making up the skin, to give it a healthy appearance or to efface surface defects, or to make the surface of the skin matt by absorbing the excess sebum.

SUBSTITUTE SHEET [RULE 26) An anhydrous depigmenting compact product especially containing nylon-β as filler, and ascorbic acid and salicylic acid as depigmenting active agents, is also available on the market. However, this type of product has the drawback of becoming unacceptably coloured when it is exposed to a humid atmosphere such as that of a bathroom, for example. This coloration has the effect of putting users off the product, in particular in the case of depigmenting products, which are supposed to give the skin a white appearance. It would therefore be desirable to have available anhydrous products, in particular in compact powder form, containing moisture-sensitive cosmetic or dermatological active agents stabilized such that these products can be stored in a bathroom without any change in their initial colour.

The Applicant has now demonstrated that by trapping these active agents in nylon particles, it is possible to avoid their degradation in a humid environment. The nylon particles are moreover capable of being compacted, unlike particles of other materials, for instance silica. In addition, by selecting particles with a mean diameter of less than or equal to 10 μm, the encapsulated active agents can enter the pilosebaceous follicles, down to their site of action, and thus act more efficiently. This therefore avoids losses of active agent in the upper layers of the epidermis and in particular on the surface of the skin where it is liable to degrade.

Patent applications FR-2 732 215 and

WO 96/21422 disclose compositions that may be anhydrous or in powder form, comprising a porous support, for example made of polyamide, on or in which is adsorbed an active agent, such as vitamin C, the support having any particle size or a size such that the active agent remains on the surface of the skin (thus greater than 10 μm) .

Patent application WO 98/58628 also discloses anhydrous bleaching compositions, optionally in powder form, which deliver active agents to the stratum corneum, the upper layer of the epidermis. These compositions contain a depigmenting agent (kojic acid), and also an exfoliant, in particular salicylic acid, adsorbed onto or in a support material such as a polyamide with a particle size of less than 20 μm, but preferably such that the exfoliant does not enter the pilosebaceous follicles, i.e. generally greater than 10 μm. The particles of the support material have the function of protecting the exfoliant in the event of incompatibility with other active agents of the composition. They contain the exfoliant, optionally in a form dissolved or dispersed in a hydrophilic support medium such as water, an alcohol or an ether.

Example 4 of patent application WO 98/58628 thus discloses an anhydrous composition containing kojic acid, and also nylon beads filled with lactic acid mixed with glycerol. This composition contains more than 65% by weight of fatty phase, which creates a protective medium with respect to ambient moisture and thus avoids the degradation of the moisture-sensitive active agents. However, it does not have the powdery feel of a compact powder.

Moreover, it is known from US-5, 876, 758 (Examples 17 and 20) anhydrous depigmenting compact powders, comprising Nylon particles of 20 μm, onto which magnesium ascorbyl phosphate is adsorbed, and also binding agents.

Also, the HAPPI database (January 2004) discloses an anhydrous face powder containing 8.75 weight percent of binding agents and powders, among which Orgasol 2002 N5 HY COS which has a size of 5 μm and contains hyaluronic acid. One also knows from US- 6,569,438 (Examples K13 and K15) sticks containing Nylon powder of 10 μm (Orgasol 1002 EXD WEISS 10 COS) charged with octoxyglycerine. The active agents contained in the Nylon particles disclosed in these two publications are either carried in water, or swellable in water, and are not considered moisture-sensitive active agents in the meaning of the present invention. There is thus still a need for a composition that may be used as a compact powder and in which moisture-sensitive active agents will be protected against degradation.

The Applicant has discovered that such a composition may be obtained by conveying these sensitive active agents in polyamide particles having a mean diameter that is small enough for these particles to enter the pilosebaceous follicles, where these active agents will be both available at their site of action and protected against moisture. More specifically, one subject of the invention is an anhydrous cosmetic composition, especially in compact form, comprising: a pulverulent phase comprising polyamide particles; a fatty phase; and at least one moisture-sensitive cosmetic or pharmaceutical active agent, characterized in that the said particles have a mean volume diameter of less than or equal to 10 μm and contain at least a fraction of the active agent, and in that the fatty phase represents from 0.1% to 20% of the weight of the composition.

A subject of the invention is also a cosmetic process for caring for greasy skin or for bleaching the skin, comprising the topical application to the skin of the abovementioned composition. A subject of the invention is also the use of this composition for the manufacture of a dermatological preparation for depigmenting the skin. The composition according to the invention comprises polyamide particles. These particles have a porous nature that allows them to adsorb a sufficient amount of active agent. They are preferably spherical, or substantially spherical, and have a mean numerical diameter of less than or equal to 10 μm and advantageously between 0.5 and 10 μm. Their specific surface area, measured by the BET method, is generally greater than 1 m²/g. The BET (Brunauer-Emmet-Teller) method is a method that is well known to those skilled in the art. It is described especially in "The Journal of the American Chemical Society", vol. 60, page 309, February 1938 and corresponds to international standard ISO 5794/1 (appendix D) . The specific surface area measured according to the BET method corresponds to the total specific surface area, i.e. it includes the area formed by the pores.

Examples of polyamide particles that may be used include particles of Nylon 6, Nylon 6-6, Nylon 12 or Nylon 6-12, in particular particles of Nylon-12, with a mean particle diameter of 10 μm, sold by the company Atofina under the trade name Orgasol 2002 EXD NAT COS, or particles of nylon-6, with a mean particle diameter range from 5 to 9 μm, sold under the trade name Micropan 777 by the company Rim-Tech.

The polyamide particles may, where appropriate, be surface-treated with at least one hydrophobic treatment agent, which is especially non- fluorinated, so long as they remain porous.

This hydrophobic treatment agent may especially be chosen from: silicones, for instance, methicones or dimethicones; fatty acids, for instance stearic acid; metal soaps, for instance aluminium dimyristate or the aluminium salt of hydrogenated tallow glutamate; amino acids, N-acylamino acids or salts thereof; lecithin or isopropyl triisostearyl titanate; and mixtures thereof.

The N-acylamino acids may comprise an acyl group containing from 8 to 22 carbon atoms, for instance a 2-ethylhexanoyl, caproyl, lauroyl, myristoyl, palmitoyl, stearoyl or cocoyl group. The salts of these compounds may be the aluminium, magnesium, calcium, zirconium, zinc, sodium or potassium salts. The amino acid may be, for example, lysine, glutamic acid or alanine. The polyamide particles may be present in the composition according to the invention in a content ranging from 0.01% to 50% by weight, preferably ranging from 0.1% to 30% by weight and preferentially from 1% to 15% by weight relative to the total weight of the composition.

These polyamide particles contain at least one cosmetic or pharmaceutical active agent, which is at least partly present inside the said particles, for example present to a proportion of at least 50%, preferably at least 70% by weight and more preferentially at least 90% by weight in the said particles, relative to the total weight of the active agent introduced into the composition.

The particles containing the active agent may be obtained according to an impregnation process comprising the following steps: - dissolution of the active agent to be encapsulated in an organic solvent with a boiling point lower than that of water at atmospheric pressure, such as acetone, isopropanol, dichloromethane or ethanol, to obtain an impregnation solution, impregnation of the polyamide particles with the said impregnation solution, evaporation of the solvent until a dry powder is obtained. This process allows the production of particles which, once introduced into an anhydrous composition, will not be liable or will only be sparingly liable to release the active agent they contain. This active agent will thus be well protected against the ambient moisture to which it is sensitive.

In addition, no hydration of the active agent will take place, which could lead in certain cases to degradation of the appearance of the powder, for example to caking of the powder.

The particles according to this invention entrap at least one moisture-sensitive active agent that can be adsorbed onto, but is at least partially absorbed into, said particles.

By "moisture-sensitive active agent", it is meant a compound providing at least one biological property when brought into contact with a living material such as skin, and which becomes at least to some extent degraded chemically, and more particularly oxidized, when contacted with water.

According to a first embodiment, the composition according to the invention is intended for caring for greasy skin, especially greasy skin with imperfections, such that the active agent that it contains preferably has sebo-regulatory and/or antibacterial and/or keratolytic and/or calmative properties. Cosmetic active agents of this type that may especially be mentioned include: seboregulators such as: retinoids, in particular retinol; sulfur and sulfur derivatives; vitamin Bβ or pyridoxine; extracts of plants such as Cinnamomum zeylanicum, Laminaria saccharina, Spiraea ulmaria, Arnica montana, Cinchona succirubra, Eugenia caryophyllata, Humulus lupulus, Hypericum perforatum, Mentha piperita, Rosmarinus officinalis, Salvia officinalis, Thymus vulgaris; Serenoa repens; and Eugenia caryophyllata;

• phytic acid, N-acetyl-L-cysteine, lipoic acid, azelaic acid and its salts, arachidonic acid, octopirox, lO-hydroxy-2-decanoic acid and phytosphingosines, and mixtures thereof;

• keratolytic agents such as β-hydroxy acids, in particular salicylic acid and its derivatives

(including 5-n-octanoyl salicylic acid) ; α-hydroxy acids, such as glycolic acid, citric acid, lactic acid, tartaric acid, malic acid or mandelic acid; urea; gentisic acid; oligofucoses; cinnamic acid; extracts of Saphora japonica; resveratrol; certain jasmonic acid derivatives; aminosulfonic compounds and in particular (N-2-hydroxyethylpiperazine-N-2- ethane) sulfonic acid (HEPES); 2-oxothiazolidine-4- carboxylic acid (procysteine) derivatives; derivatives of α-amino acids of glycine type (as described in EP 0 852 949, such as the sodium methyl glycine diacetate sold by BASF under the trade name Trilon M) ; honey; and sugar derivatives such as O-octanoyl-6-D-maltose and N- acetylglucosamine;

• anti-inflammatory agents or calmatives such as: pentacyclic triterpenes and plant extracts (e.g.: Glycyrrhiza glabra) containing them; oleanolic acid and its salts; betulinic acid and its salts; salicylic acid salts, in particular zinc salicylate; extracts of plants such as Paeonia suffruticosa and/or lactiflora, Laminaria saccharina, Pygeum, Boswellia serrata, Centipeda cunnighami, Helianthus annuus, Linum usitatissimum, Cola nitida, Epilobium angustifolium, Aloe vera, Bacopa monieri; bisabolol and camomile extracts; allantoin; the phosphoric diester of vitamins E and C sold especially by the company SEPPIC; omega-3 unsaturated oils such as musk rose oil, blackcurrant oil or Echium oil; capryloyl glycine; • tocotrienols; piperonal, and phytosterols. According to a second embodiment, the composition according to the invention is intended for bleaching or depigmenting the skin, such that the active agent that it contains preferably has the property of inhibiting tyrosinase and/or of reducing the dendricity of the melanocytes.

In this case, it may be used for cosmetic purposes to lighten the complexion and may comprise, as cosmetic active agent, at least one compound chosen from: kojic acid; ellagic acid; arbutin and its derivatives such as those described in patent applications EP-895 779 and EP-524 109; hydroquinone; aminophenol derivatives such as those described in patent applications WO 99/10318 and WO 99/32077,and in particular N-cholesteryloxycarbonyl-para-aminophenol and N-ethyloxycarbonyl-para-aminophenol; iminophenol derivatives, in particular those described in patent application WO 99/22707; L-2-oxothiazolidine-4- carboxylic acid or procysteine, and also its salts and esters; calcium D-pantheteine sulfonate; ascorbic acid and its derivatives, especially ascorbyl glucoside; and extracts of plants, in particular of liquorice, of mulberry, of skullcap and of Bacopa monnieri. As a variant, it may be used for dermatological purposes, to treat regional hyperpigmentations caused by melanocyte hyperactivity, such as idiopathic melasmas, occurring during pregnancy ("pregnancy mask" or chloasma) or during oestro- progestin contraception, localized hyperpigmentations caused by hyperactivity and benign melanocyte proliferation, such as senile pigmentation marks known as actinic lentigo, or accidental hyperpigmentations, possibly caused by photosensitization or post-lesional cicatrization. The composition according to the invention may also be used in the treatment of certain leucodermas, such as vitiligo. For the latter conditions (cicatrizations that may result in a scar giving the skin a whiter appearance) , failing the ability to repigment the damaged skin, the areas of residual normal skin are depigmented to give the skin as a whole a uniform white hue. In this case, the composition according to the invention may comprise hydroquinone as pharmaceutical active agent.

The composition according to the invention may also comprise pigments and/or fillers conventionally used in products in compact powder form.

The term "pigments" should be understood as meaning white or coloured, mineral or organic particles of any form, which are insoluble in the composition and are intended to colour it. The pigments may be white or coloured, and mineral and/or organic.

Among the mineral pigments that may be mentioned are titanium dioxide, optionally surface- treated, zirconium oxide and cerium oxide, and also zinc oxide, iron oxide (black, yellow or red) or chromium oxide, manganese violet, ultramarine blue, chromium hydrate and ferric blue, and metal powders, for instance aluminium powder or copper powder. The pigments may also be chosen from metal oxide nanopigments, such as titanium dioxide, zinc oxide, iron oxide, zirconium oxide or cerium oxide, and mixtures thereof. The term "nanopigments" means pigments with a mean particle size ranging from 1 nm to 500 nm and preferably ranging from 10 nm to 100 nm.

Among the organic pigments that may be mentioned are carbon black, pigments of D & C type, and lakes, especially lakes based on cochineal carmine, barium, strontium, calcium or aluminium.

The pigments may be present in the composition in a content ranging from 0.1% to 15% by weight, preferably from 0.5% to 12% by weight and preferentially from 1% to 10% by weight relative to the total weight of the composition.

The compact powder according to the invention may comprise an additional pulverulent dyestuff other than the pigments described above, which may especially be chosen from nacres.

The term "nacres" should be understood as meaning iridescent particles of any form, especially produced by certain molluscs in their shell or else synthesized. The nacres may be chosen from white nacres such as mica coated with titanium or with bismuth oxychloride, coloured nacres such as titanium mica coated with iron oxides, titanium mica coated especially with ferric blue or with chromium oxide, titanium mica coated with an organic pigment of the abovementioned type, and also nacres based on bismuth oxychloride. The nacres may be present in the composition in a content ranging from 0.1% to 50% by weight, preferably from 0.1% to 40% by weight and preferentially from 0.1% to 30% by weight relative to the total weight of the composition. The composition according to the invention may also or as a variant comprise fillers other than the polyamide particles, nacres and pigments described above.

The term "fillers" should be understood as meaning colourless or white, mineral or organic particles of any form, which are insoluble in the medium of the composition irrespective of the temperature at which the composition is manufactured, and which do not colour the composition. The fillers may be of any form, platelet- shaped, spherical or oblong, irrespective of the crystallographic form (for example lamellar, cubic, hexagonal, orthorhombic, etc.) . Mention may be made of: talc, mica, silica, kaolin, poly-β-alanine and polyethylene, powders of tetrafluoroethylene polymers

(Teflon®) , lauroyllysine, starch, boron nitride, hollow polymer microspheres such as those of polyvinylidene chloride/acrylonitrile, for instance Expancel® (Nobel Industrie) or of acrylic acid copolymers, silicone resin microbeads (for example Tospearls® from Toshiba) , elastomeric polyorganosiloxane particles, precipitated calcium carbonate, magnesium carbonate, magnesium hydrocarbonate, hydroxyapatite, barium sulfate, aluminium oxides, polyurethane powders, composite fillers, hollow silica microspheres, and glass or ceramic microcapsules. The composition may also contain metal soaps derived from organic carboxylic acids containing from 8 to 22 carbon atoms and preferably from 12 to 18 carbon atoms, for example zinc stearate, magnesium stearate, lithium stearate, zinc laurate or magnesium myristate. The fillers may be present in the composition in a content ranging from 0.1% to 95% by weight, preferably from 1% to 85% by weight and preferentially from 1% to 80% by weight relative to the total weight of the composition. The fatty phase of the compact powder, generally referred to as binder, is a phase that is fatty at room temperature (25°C) , consisting of water- insoluble liguid or waxy compounds that have no surfactant properties within the meaning of the McCutcheon and CTFA dictionaries. This fatty phase may comprise one or more oils and/or waxes, commonly used in compact powders. Among the oils and waxes that may be used, mention may be made of soybean oil, grapeseed oil, .sesame seed oil, corn oil, rapeseed oil, sunflower oil, cottonseed oil, avocado oil, olive oil, castor oil, jojoba oil, or groundnut oil; hydrocarbon oils, such as liquid paraffin, squalane, petroleum jelly and polydecene; fatty esters, such as isopropyl myristate, isopropyl palmitate, butyl stearate, isodecyl stearate, hexyl laurate, isononyl isononanoate, 2-ethylhexyl palmitate, 2-hexyldecyl laurate, 2-octyldecyl palmitate, 2-octyldodecyl myristate or lactate, 2- diethylhexyl succinate, diisostearyl malate, and glyceryl or diglyceryl triisostearate; silicone oils such as polymethylsiloxanes, polymethylphenylsiloxanes, polysiloxanes modified with fatty acids, fatty alcohols or polyoxyalkylenes, fluoro silicones or perfluoro oils; oleic acid, linoleic acid, linolenic acid, higher fatty acids such as cetanol or oleyl alcohol.

The fatty phase may be present in a content ranging from 0.1% to 20% by weight, preferably from 0.1% to 15% by weight and preferentially from 0.1% to 10%- by weight relative to the total weight of the composition.

The composition may comprise other ingredients (adjuvants) usually used in cosmetics, such as preserving agents, UV-screening agents, thickeners, surfactants and fragrances . Needless to say, a person skilled in the art will take care to select the optional adjuvant (s) added to the composition according to the invention such that the advantageous properties intrinsically associated with the composition according to the invention are not, or are not substantially, adversely affected by the envisaged addition.

The composition according to the invention is an anhydrous composition, i.e. a composition containing less than 2% by weight of water, or even less than 0.5% of water, and especially free of water, the water not being added during the preparation of the composition, but corresponding to the residual water introduced by the mixed ingredients. The composition is advantageously in the form of a compact powder, which may be prepared by mixing the ingredients of the pulverulent phase (optional polyamide particles, fillers, nacres and pigments) , followed by adding the fatty phase with stirring, the mixture then being ground (for example in a powder mill of Baker type) , screened and then poured into a dish and compacted.

The ground and screened mixture of the pulverulent phase and of the fatty phase is compacted, for example, using a press, especially by applying a pressure ranging from 0.5 MPa to 10 MPa and preferably ranging from 1 MPa to 5 MPa. The invention is illustrated in greater detail by the non-limiting example now described.

Example Two compact powders having the composition indicated in Table 1 below were prepared:

Table 1

Procedure:

The filled particles were prepared in the following manner: a solution containing 20 g of salicylic acid, 1 1 of acetone and 200 g of Nylon-12 (Orgasol 2002 UD NAT COS 204 - Atofina) was prepared. This solution was stirred at room temperature until dissolution of the active agent was complete. The solution was then transferred into a round-bottomed flask and the acetone was evaporated off on a Rotavapor at 40⁰C. After complete evaporation of the solvent, a powder was thus obtained consisting of nylon particles whose pores are filled with salicylic acid in solid form.

The compact powder containing these filled particles was then prepared in a standard manner for those skilled in the art. Stability test:

The stability of compositions A and B above was evaluated. To do this, these compositions were packaged in a 10 g case. The cases were then placed for two months in an oven under a relative humidity of 80% and at a temperature of 45°C. The macroscopic appearance of the powders after storage in the oven was then evaluated. After two months, composition A was in the form of a pinkish powder with dark pink spots, whereas composition B was in the form of a white powder with no coloration at the surface or in the bulk.

These results show that after prolonged storage in a humid atmosphere, the composition according to the invention shows no unattractive coloration.

Claims

1. Anhydrous cosmetic composition comprising: a pulverulent phase comprising polyamide particles; a fatty phase; and at least one moisture- sensitive cosmetic or pharmaceutical active agent, characterized in that the said particles have a mean volume diameter of less than or equal to 10 μm and contain at least a fraction of the active agent, and in that the fatty phase represents from 0.1% to 20% of the weight of the composition.

2. Composition according to Claim 1, characterized in that the polyamide particles are present in the composition in a content ranging from 0.01% to 50% by weight relative to the total weight of the composition.

3. Composition according to Claim 2, characterized in that the polyamide particles are present in the composition in a content ranging from 0.1% to 30% by weight relative to the total weight of the composition.

• 4. Composition according to Claim 3, characterized in that the polyamide particles are present in the composition in a content ranging from 1% to 15% by weight relative to the total weight of the composition.

5. Composition according to any one of Claims 1 to 4, characterized in that the particles containing the active agent may be obtained according to an impregnation process comprising the following steps: - dissolution of the active agent to be encapsulated in an organic solvent with a boiling point lower than that of water at atmospheric pressure, to obtain an impregnation solution, - impregnation of the polyamide particles with the said impregnation solution, evaporation of the solvent until a dry powder is obtained.

6. Composition according to any one of Claims 1 to 5, characterized in that the active agent that it contains has sebo-regulatory and/or antibacterial and/or keratolytic and/or calmative properties.

7. Composition according to any one of Claims 1 to 5, characterized in that the active agent that it contains has the property of inhibiting tyrosinase and/or of reducing the dendricity of the melanocytes.

8. Composition according to Claim β or 7, characterized in that the active agent is salicylic acid or 5-n-octanoylsalicylic acid.

9. Composition according to Claim 6 or 7, characterized in that the active agent is ascorbic acid.

10. Composition according to any one of Claims 1 to 9, characterized in that the fatty phase is present in a content ranging from 0.1% to 10% by weight relative to the total weight of the composition.

11. Composition according to any one of

Claims 1 to 10, characterized in that it is in the form of a compact powder.

12. Cosmetic process for caring for greasy skin or for bleaching the skin, comprising the topical application to the skin of the composition according to any one of Claims 1 to 11.

13. Use of the composition according to any one of Claims 1 to 11 for the manufacture of a dermatological preparation for depigmenting the skin.