High skin friction cosmetic creams with retinoids

Details High skin friction cosmetic creams with retinoids High skin friction cosmetic creams with retinoids

2001-07-26

2002-09-17

Krass, Frederick (Department: 1614)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Cosmetic, antiperspirant, dentifrice

C424S489000, C424S502000, C514S558000, C514S772300, C514S844000, C514S846000, C514S937000, C514S951000, C514S970000

Reexamination Certificate

active

06451330

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to cosmetic skin creams containing a retinoid and providing a high skin friction.
BACKGROUND OF THE INVENTION
Consumers living in hot, humid climates, or consumers with oily skin, desire cosmetic products which have unique tactile properties during use. Specifically, such products should upon application to the skin, deliver a high skin friction and a matte finish to overcome the oily skin feel and shiny skin appearance. The greater the increase in skin friction, the less greasy the user perceives the product to be. See Laufer et al., Objective Measurement and Self-Assessment of Skin-Care Treatments, Cosmetics and Toiletries Magazine, Vol. 111, June 1996, pp. 92-96.
Retinoids are known to provide a wide spectrum of skin benefits such as skin lightening, wrinkle treatment, oil control. Unfortunately, retinoids are unstable, especially in the presence of water. High friction skin creams, however, employ water. Thus, there is a challenge to provide cosmetic creams delivering high skin friction, yet containing retinoids which remain sufficiently stable upon storage in the creams.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a cosmetic composition including:
(a) at least about 2% by weight of the composition of solid asymmetric particles;
(b) a retinoid solubilized in a fluid oil; and
wherein the fluid oil to the solid particles are present in a weight ratio such that the composition exhibits a normal force value of less than −100 milli-Newton (mN).
The present invention also provides a method of controlling or preventing an oily skin appearance and/or feel especially in the facial area, by applying to the skin the inventive composition.
DETAILED DESCRIPTION OF THE INVENTION
Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about.” All amounts are by weight of the final composition, unless otherwise specified.
The term “skin” as used herein includes the skin on the face, neck, chest, back, arms, hands, legs and scalp.
The term “solid” as used herein means that the material is not fluid at 25° C.
The term “fluid” as used herein means that the material is fluid at 250° C.
Asymmetric Particles
The inventive compositions comprise asymmetric solid particles. Asymmetric is understood to mean that at least two of three dimensions on a majority of the particles are not size identical. These particles can be oval or plate-like. Average particle size along greatest length may range from 0.01 to 500 micron and preferably from 1 to 100 micron. The particles are employed in the composition to impart a cream-like viscosity. Furthermore, by virtue of being asymmetric, the particles deliver high skin friction. Suitable solid particles include but are not limited to fatty acid crystals, mica, talc, clays and mixtures thereof. The preferred solid particles are selected from the fatty acid crystals wherein fatty acid contains from 12-22 carbon atoms, because they are inexpensive and the most aesthetically acceptable. The most preferred fatty acid is stearic acid. The term “acid” as employed herein does not exclude the presence of a salt of fatty acid depending on the pH of the final composition. For instance, sodium, potassium or ammonium salts may be present. The salt amount is included in the amount of fatty acid. The inventive compositions contain at least 2% of the asymmetric solid particles, preferably at least 10%, more preferably from 10% to 20%, and optimally from 16% to 20% to obtain the best feel, appearance, and viscosity. The exact amount depends on the final composition and the nature of the other ingredients in the composition. The amount of the asymmetric solid particles, however, must be sufficient to impart the cream-like consistency to the composition, i.e. the viscosity of greater than about 40 Pascal-second (PaS) at a shear rate of one reciprocal second(1/s), preferably the viscosity is from about 40 PaS to about 200 PaS, most preferably from about 60 PaS to about 120 PaS, in order to provide a cream consistency that can be rubbed in easily.
The procedure for measuring viscosity is as follows:
Viscosity is measured using any viscometer or rheometer with a shear rate of 1/s, at an ambient temperature (20-25° C.). Such viscometers/rheometers are Brookfield, Haake, and Bohlin with cone and plate fixtures.
In the inventive compositions, the solid asymmetric particles are dispersed in water.
Retinoid Solubilized in a Fluid Oil
The inventive compositions contain a retinoid. Suitable retinoids include but are not limited to retinyl esters, retinol, retinal and retinoic acid, preferably retinol or retinyl ester. The term “retinol” includes the following isomers of retinol: all-trans-retinol, 13-cis-retinol, 11-cis-retinol, 9-cis-retinol, 3,4-didehydro-retinol, 3,4-didehydro-13-cis-retinol; 3,4-didehydro-11-cis-retinol; 3,4-didehydro-9-cis-retinol. Preferred isomers are all-trans-retinol, 13-cis-retinol, 3,4-didehydro-retinol, 9-cis-retinol. Most preferred is all-trans-retinol, due to its wide commercial availability.
Retinyl ester is an ester of retinol. The term “retinol” has been defined above. Retinyl esters suitable for use in the present invention are C
1
-C
30
esters of retinol, preferably C
2
-C
20
esters, and most preferably C
2
, C
3
, and C
16
esters because they are more commonly available. Examples of retinyl esters include but are not limited to: retinyl palmitate, retinyl formate, retinyl acetate, retinyl propionate, retinyl butyrate, retinyl valerate, retinyl isovalerate, retinyl hexanoate, retinyl heptanoate, retinyl octanoate, retinyl nonanoate, retinyl decanoate, retinyl undecandate, retinyl laurate, retinyl tridecanoate, retinyl myristate, retinyl pentadecanoate, retinyl heptadeconoate, retinyl stearate, retinyl isostearate, retinyl nonadecanoate, retinyl arachidonate, retinyl behenate, retinyl linoleate and retinyl oleate.
The preferred ester for use in the present invention is selected from retinyl palmitate, retinyl acetate and retinyl propionate, because these are the most commercially available and therefore the least expensive. Retinyl linoleate and retinyl oleate are also preferred due to their efficacy.
The retinoid is employed in the inventive composition in an amount of at least about 0.001%, preferably from about 0.001% to about 10%, more preferably from about 0.01% to about 1%, optimally from about 0.01% to about 0.5% by weight of the composition.
The retinoid present in the inventive composition is solubilized in a fluid oil in order to improve the storage stability of the retinoid. Suitable fluid oils are selected in such a manner that the retinoid is soluble in an amount of at least 1 gram of retinoid per 100 grams of the oil at 25° C. Preferably the retinoid is soluble in an amount of at least 10 grams of the retinoid per 100 grams of the oil, most preferably 50 grams of the retinoid per 100 grams of the oil.
As an illustration, solubility of retinol crystals in varying oils is as follows:
OIL
SOLUBILITY, WT %
Mineral oil
34.2
Cetiol OE
45
Isostearyl palmitate
44
C12-15 Alkyl benzoate
85
Triolein/Squalene (6:1)
56.4
Cyclomethicone
2.7
Dimethicone
0.49
Retinoid solubility in oil is determined by the following procedure. A known weight of pure retinoid in excess of the expected solubility limit in the oil is added in an oil and methanol is added to the mixture to dissolve all retinoid crystals. Nitrogen sparging is used to ensure all methanol has evaporated from the oil. Retinoid is allowed to recrystallize overnight. The sample is filtered through a 0.45 micron filter. Known dilutions of the filtrate in isopropanol are measured by UV spectroscopy at an appropriate wavelength (325 nm for retinol) and the concentration of retinoid determined against calibration standards of retinoid in isopropanol.
Suitable fluid oils include but are not limited to esters of fatt

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