WO1995035088A1 - Cosmetic and/or pharmaceutical o/w emulsions - Google Patents

Abstract

New cosmetic and/or pharmaceutical O/W emulsions are produced by emulsifying an oil phase that contains pseudoceramides of the alkyl succinic acid ester type having the formula (I) in water at a temperature above the phase inversion temperature. In the formula (I), R<1> stands for an alkyl and/or alkenyl residue with 6 to 22 carbon atoms, R<2> stands for hydrogen or R<1>, R<3> and R<4> represent independently from each other hydrogen or an alkyl and/or alkenyl residue with 6 to 22 carbon atoms, provided that at the maximum one of these residues stands for hydrogen and that the sum (n+p) equals 1 to 20. These emulsions are extremely stable even when their pseudoceramide content is high, and when topically applied they reduce transepidermal water loss.

Description

 Cosmetic and / or pharmaceutical O / W emulsions

Field of the Invention

The invention relates to cosmetic and / or pharmaceutical O / W emulsions containing selected pseudoceramides which are obtained by the phase inversion temperature method, a process for the preparation of the emulsions and their use for the production of skin care products.

State of the art

A balanced water balance in the biogenic bar functions of the individual skin layers plays an important role for the elasticity and appearance of the skin. The bound water content is greatest in the dermis and in the boundary layer of the epidermis near the basement membrane. The elasticity and the state of tension of the skin is decisively shaped by the collagen and elastin fibers in the dermis, the specific conformation of the collagen being achieved by the incorporation of water molecules.

A destruction of the lipid barrier in the stratum corneum (SC), for example by surfactants, leads to an increase in transepidermal water loss and dehydration of the skin. Since the water bound in the deeper layers of the skin can only be supplied via the body fluid via vessels, but not from the outside, it becomes clear that maintaining the barrier function of the stratum corneum is essential for the overall condition of the skin [cf. SEFriberg et al. , CR 23rd CED Congress, Barcelona, 1992, p.29].

Ceramides are lipophilic amides of long-chain fatty acids, which are generally derived from sphingosine or phytosphingosine. This class of endogenous fatty substances has gained considerable importance since they have been recognized in the intercellular space between the corneocytes as key components for the structure of the lipid bilayer, ie the permeability barrier, in the stratum corneum of human skin. Ceramides have molecular weights of significantly less than 1000, so that the external site of a cosmetic formulation makes it possible to reach the site of action. The external application of ceramides leads to the restructuring of the lipid barrier, which can cause the described disorders of the skin function to be counteracted [cf. R.D. Petersen, Cosm.Toil. 107, 45 (1992)].

So far, the use of ceramides has been limited due to their lack of availability. There have therefore already been attempts to synthesize ceramide-analogous structures, so-called "synthetic barrier lipids (SBL)" or "pseudoceramides" and to use them for skin care [cf. G.Imokawa et al. J. Soc. Cosmet.Chem. .40., 273 (1989)]. However, the skin cosmetic properties of these substitutes are not always satisfactory. Skin care products on the market usually contain ceramides or pseudo-doceramides in concentrations well below 1% by weight. The main reason for this is the fact that the substances mentioned generally have unsatisfactory solubility. Especially in the production of emulsions or clear formulations such as lipogels and oils, instabilities occur due to the addition of ceramides and pseudoceramides.

The object of the invention was to provide emulsions with an increased content of pseudoceramides, which are at the same time characterized by improved storage stability and improved skin cosmetic properties.

Description of the invention

The invention relates to cosmetic and / or pharmaceutical O / W emulsions, obtainable by adding an oil phase containing pseudoceramides of the alkyl succinic acid ester type of the formula (I),

R ³ R ⁴

I I

R ¹ 0 (CH2CH2θ) _n CO-CH-CH-CO (OCH2CH2) _ιn OR ² (I)

in which R ^{1 represents} an alkyl and / or alkenyl radical with 6 to 22 carbon atoms, R ^{2 represents} hydrogen or R ¹ and R ³ and R ⁴ independently of one another represent hydrogen or an alkyl and / or alkenyl radical with 6 to 22 carbons, with the Provided that at most one of these two radicals can be hydrogen, and the sum (n + p) stands for numbers from 1 to 20, emulsified with water in the range above the phase inversion temperature.

A particular embodiment of the invention relates to 0/W emulsions which have a pseudoceramides content in the range from 5 to 10 and in particular 7 to 9% by weight.

Surprisingly, it was found that the use of the phase inversion temperature method known per se allows the production of stable emulsions with a significantly increased content of selected pseudoceramides. The "PIT concentrates" obtained in this way are further distinguished from commercially available skin care products when applied topically by a reduced transepidermal water loss.

The invention further relates to a process for the preparation of cosmetic and / or pharmaceutical O / W emulsions, in which an oil phase containing pseudoceramides of the alkyl succinic acid ester type of the formula (I)

_R 3 R4

IIR ¹ 0 (CH ₂ CH2θ) _n CO-CH-CH-CO (OCH ₂ CH2) _m OR ² (I)

in which \\ stands for an alkyl and / or alkenyl radical with 6 to 22 carbon atoms, R ² for hydrogen or R ¹ and R ^ and R ⁴ independently of one another for hydrogen or an alkyl and / or alkenyl radical with 6 to 22 carbons , with the Provided that at most one of these two radicals can be hydrogen, and the sum (n + p) stands for numbers from 1 to 20, emulsified with water above the phase inversion temperature.

Pseudoceramides

Alkyl succinic acid esters are suitable as pseudoceramides. These substances are known pseudoceramides which can be obtained, for example, according to DE-Al 4238032 (Hen¬ kel) by ring opening of alkylsuccinic anhydrides with alcohols and subsequent base-catalyzed reaction with ethylene oxide. If necessary, hardening can follow as a further step. The alkyl succinic acid esters can be present as diesters, but monoesters are preferably used. In the course of the ethoxylation, ethylene oxide groups are inserted into the ester bond or the free carboxyl function is esterified. The insertion reaction proceeds statistically, accordingly the degree of ethoxylation does not allow any conclusion to be drawn about the distribution of the EO groups, but only about the molar ratio used.

Typical examples of pseudoceramides which come into consideration in the sense of the invention are addition products of an average of 1 to 20, preferably 2 to 10 and in particular 6 to 8 moles of ethylene oxide with hexostecylsuccinic acid monostearyl ester, hexadecylsuccinic acid distearyl ester, ocotadecylsuccinic acid monopalmitine esters and the like. In total, preference is given to alkyl succinic acid esters of the formula (I) in which R ¹ and R ^{2 are} alkyl radicals with 12 to 22 and preferably 16 to 22 carbon atoms, R ³ for alkyl radicals with 16 to 18 carbon atoms, R ⁴ for hydrogen and the sum (n + m) for numbers from 6 to 8 stands. Typical examples of this are an adduct of an average of 7.6 mol of ethylene oxide onto a hexadecylsuccinic acid monostearyl ester or a hexadecylsuccinic acid monobehenyl ester 7.5 EO adduct.

The pseudoceramides are preferably used in concentrations of 5 to 10 and in particular 7 to 9% by weight, based on the emulsion.

oil body

Examples of suitable oil bodies are:

*** Guerbet alcohols based on fatty alcohols with 6 to 18, preferably 8 to 10 carbon atoms, such as e.g. 2-hexyldecanol or 2-octyldodecano;

C24 Cg-fatty acids esters of linear pick *** with linear C20 CSS ^fetta lk °, stearate such as Palmitylmyristat, stearyl or Kokosfettsäurelaurylester;

*** esters of branched Ci3 CSS ~ carboxylic acids with linear CISS-Cig fatty alcohols, ^w h ^e example 2-Ethylhexansäurestea- rylester or Isotridecansäurepalmitylester;

*** esters of linear C 1 -C 8 fatty ^{acids with} branched alcohols, in particular 2-ethylhexanol, such as 2-ethylhexyl coconut fatty acid;

*** Esters of linear and / or branched fatty acids with dihydric alcohols and / or Guerbet alcohols, such as eg 2-ethylhexyl isostearic acid or 2-octyldodecyl isopalmitate;

z.B. tech¬ nische Gemische von Capron-, Caryl- und Caprinsäuregly- ceriden;*** Triglycerides based

eg technical mixtures of capronic, caryl and capric acid glycerides;

vegetable oils, such as Almond oil, olive oil, sunflower oil and the like;

branched primary alcohols, e.g. Isostearyl alcohol;

substituted cyclohexanes such as e.g. Di-n-octylcyclohexane;

*** Guerbet carbonates, e.g. Bis-2-octyldodecyl carbonate and / or

Dialkyl ethers, e.g. Di-n-octyl ether.

The oil bodies can be used in amounts of 10 to 80, preferably 20 to 60 and in particular 30 to 50% by weight, based on the emulsion.

Emulsifiers

Examples of suitable emulsifiers are:

*** hardened and ethoxylated castor oil,

*** polyglycerol fatty acid esters, such as polyglycerol isostearates, *** polyol polyhydroxycarboxylic acid esters, such as polyglycerol polyricinoleates and / or polyglycerol polyhydroxy stearates, *** sorbitan esters, such as sorbitan mono-, -sesqui-, -bis- or -trilaurate , palmitate, stearate or oleate; *** Polysorbates, such as the adducts of 1 to 40 moles of ethylene oxide with the sorbitan esters mentioned;

*** fatty alcohols with 6 to 22 carbon atoms and their adducts with 1 to 20 moles of ethylene oxide;

*** partial ^esters of glycerin with C6-C22 ^{fatty acids} _'

The emulsifiers can be used in amounts of 1 to 10, preferably 4 to 8% by weight, based on the emulsion.

Phase inversion temperature method (PI ^

The phase inversion temperature method is a known method for the hot emulsification of fatty substances in aqueous systems. Cosmetic emulsions which can be obtained by this method are described, for example, in German patent applications DE-Al 3819193, DE-Al 4010393, DE-Al 4140562, DE-Al 4243272 and DE-Al 4318171 (Henkel).

Skin care products

The skin care products can contain minor amounts of other surfactants that are compatible with the other ingredients. Typical examples are fatty alcohol polyglycol ether sulfates, monoglyceride sulfates, ether carboxylic acids, mono- and / or dialkyl sulfosuccinates, fatty acid isethionates, fatty acid desarcosinates, alkyl and fatty acid / taurides. or alkenyl oligoglucosides, alkyl amido betaines and / or protein hydrolyzates or their condensates with fatty acids on an animal or preferably vegetable basis.

Further auxiliaries and additives are fats and waxes, stabilizers, thickeners, biogenic agents, film formers, fragrances, dyes, pearlescent agents, preservatives, UV filters, pigments, electrolytes (eg magnesium sulfate) and pH regulators Consideration.

Typical examples of fats are glycerides, waxes which may be used include beeswax, paraffin wax or microwaxes, if appropriate in combination with hydrophilic waxes, for example cetylstearyl alcohol. Metal salts of fatty acids such as magnesium, aluminum and / or zinc stearate can be used as stabilizers. Suitable thickeners are, for example, crosslinked polyacrylic acids and their derivatives, polysaccharides, in particular xanthan gum, GuarrGuar, agar agar, alginates and tyloses, carboxymethyl cellulose and hydroxyethyl cellulose, and also fatty alcohols, monoglycerides and fatty acids, polyacrylates, polyvinyl alcohol and polyvinyl pyrrolid. Biogenic active substances are understood to mean, for example, plant extracts, protein hydrolyzates and vitamin complexes. Common film formers are, for example, hydrocolloids such as chitosan, microcrystalline chitosan or quaternized chitosan, polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymers, polymers of the acrylic acid series, quaternary cellulose derivatives and similar compounds. Suitable preservatives are, for example, formaldehyde solution, p-hydroxybenzoate or sorbic acid. Examples of pearlescent agents are glycol distearic acid esters such as ethylene glycol distearate, but also fatty acids and fatty acid mono- glycolester into consideration. The dyes which can be used are the substances which are suitable and approved for cosmetic purposes, as compiled, for example, in the publication "Cosmetic Dyes" by the Dye Commission of the German Research Foundation, published by Chemie Publishing House, Weinheim, 1984. These dyes are usually used in concentrations of 0.001 to 0.1% by weight, based on the mixture as a whole.

The total proportion of auxiliaries and additives can be 1 to 50, preferably 5 to 40% by weight and the non-aqueous proportion (“active substance content”) 20 to 80, preferably 30 to 70% by weight, based on the composition.

Industrial applicability

The cosmetic and / or pharmaceutical O / W emulsions according to the invention with an increased content of pseudoceramides are distinguished by a particular stability and a reduced transepidermal water loss when applied topically to the skin.

Another object of the invention therefore relates to the use of the O / W emulsions for the production of skin care products, such as hand creams, nutritional creams, day creams, night creams, moisturizers, hand lotions, sun creams and the like.

The following examples are intended to explain the subject matter of the invention in more detail without restricting it. Examples

I. Substances used

A) Pseudoceramides

AI) Hexadecylsuccinic acid monobehenyl ester 7.5E0 adduct A2) Hexadecyl succinic acid monostearyl ester 7.6E0 adduct

B) oil body

B1) CETI0L ( ^R ) S (di-n-octylcyclohexane) B2) CETI0L ( ^R ) OE (di-n-octyl ether)

C) Emulsifiers

Cl) DEHYMULS ( ^R ) (Hardened castor oil-7 EO adduct) C2) EUMULGIN ( ^R ) Bl (cetylstearyl alcohol-12 EO adduct) C3) EUMULGIN ( ^R ) SML 20 (sorbitan monolaurate-20 EO adduct)

II. Preparation of the O / W emulsions

The O / W emulsions according to the invention from Examples 1 to 3 and Comparative Example VI were prepared by the PIT method, ie above the phase inversion temperature. The comparison emulsions V2 and V3 were prepared below the PIT. Percentages as% by weight (water ad 100% by weight). The emulsions were assessed visually for their distribution and storage stability (2 weeks, 40 ° C.). The results are summarized in Table 1: Table 1 Composition of the O / W emulsions

E.g. cAl cA2 CBI cB2 cCl cC2 cC3 Emul.

%%%%%%%

1 7.6 40.0 7.6 +++ 2 8.3 40.0 7.0 +++ 3 8.3 40.0 7.0 ++

VI 40.0 8.6 5.4 + V2 7.6 - 40.0 6.4 V3 40.0 - 8.6 5.4 -

Legend: c (X) = concentration component X Emul. = Emulsion

+++ finely divided, no segregation

++ finely divided, slight segregation

+ finely divided, rough separation, rough separation, strong separation

The examples and comparative examples show that finely divided, storage-stable O / W emulsions with a high proportion of pseudoceramide can only be prepared by the PIT method.

III. Transepidermal water loss of the O / W emulsions

To investigate the transepidermal water loss (TEWL) as a measure of the smoothing of the skin associated with the use of the skin care products, initially unboiled pig epidermis was treated with a 10% by weight solution of sodium lauryl sulfate (pH 5.5) over a period of 2 h at 40 ° C pre-damaged (standard = 100% TEWL). The product according to Example 1 and the comparative product VI were then applied in excess and were able to penetrate the porcine epidermis at 35 ° C. over a period of 1 to 20 h. The excess was then removed by rinsing and dabbing and the surface was dried. The TEWL value was determined compared to the standard. The results are summarized in Table 2:

Table 2: Transepidermal water loss

Example TEWL (%) after h

1 2 3 4 5 8 10 12 15 20

1 87 86 86 85 85 84 84 83 82

VI 94 94 93 93 92 91 90 89 88 87

Claims

 Claims Cosmetic and / or pharmaceutical O / W emulsions, obtainable by an oil phase containing pseudo-doceramides of the alkyl succinic acid ester type of the formula (I), _R 3 R4 IIR ¹ 0 (CH2CH ₂ 0) _n CO-CH-CH-CO (OCH2CH2) _m OR ² (I) in which R ^{1 is} an alkyl and / or alkenyl radical with 6 to 22 carbon atoms, R ² for hydrogen or R and 3 and R ⁴ independently of one another are hydrogen or an alkyl and / or alkenyl radical with 6 to 22 carbons, with the proviso that at most one of these two radicals can be hydrogen, and the sum (n + p) stands for numbers from 1 to 20, emulsified with water above the phase inversion temperature. O / W emulsions according to Claim 1, characterized in that they have a content of alkyl succinic esters of the formula (I) of 5 to 10% by weight, based on the emulsion. Process for the preparation of cosmetic and / or pharmaceutical O / W emulsions, in which an oil phase containing pseudoceramides of the alkyl succinic acid ester type of the formula (I), R3 _R II Rio (CH ₂ CH2θ) _n CO-CH-CH-CO (OCH ₂ CH2) _m OR ² (I) in which R ^{1 is} an alkyl and / or alkenyl radical having 6 to 22 carbon atoms, R ^{2 is} hydrogen or R ¹ and R ³ and R ^{4 are,} independently of one another, hydrogen or an alkyl and / or alkenyl radical having 6 to 22 carbons with the proviso that at most one of these two radicals can be hydrogen, and the sum (n + p) stands for numbers from 1 to 20, emulsified with water above the phase inversion temperature. Process according to Claim 3, characterized in that the pseudoceramides are used in amounts of 5 to 10% by weight, based on the emulsion. Process according to claims 3 and 4, characterized gekenn¬ characterized in that oil bodies selected from the group consisting of Guerbet alcohols based on fatty alcohols having 6 to 18 carbon atoms, esters of linear C5-C20 fatty acids with linear Cg-C20 ^fatty alcohols , Esters of branched Cg-Ci3 ~ carboxylic acids with linear Cig-Cig fatty alcohols, esters of linear CiQ-Cig fatty acids with branched alcohols, esters of linear and / or branched fatty acids with dihydric alcohols and / or Guerbet alcohols, triglycerides based Cg- Cιo ~ ^{fatty acids} vegetable oils, branched primary alcohols, substituted cyclohexanes, Guerbet carbonates and / or dialkyl ethers is used. 6. The method according to claims 3 to 5, characterized gekenn¬ characterized in that the oil bodies in amounts of 10 to 80 wt .-% - based on the emulsion - used. 7. The method according to claims 3 to 6, characterized gekenn¬ characterized in that emulsifiers selected from the group consisting of hardened and ethoxylated castor oil, polyglycerol fatty acid esters, polyglycerol polyricinoleates, polyglycerol polyhydroxystearates, sorbitan esters, polysorbates, fatty alcohols and their / ethylene oxide ducts or partial glycerides is formed. 8. The method according to claims 3 to 7, characterized gekenn¬ characterized in that the emulsifiers in amounts of 1 to 10 wt .-% - based on the emulsion - uses. 9. Use of O / W emulsions according to claim 1 for the manufacture of skin care products.