Drug – bio-affecting and body treating compositions – Plant material or plant extract of undetermined constitution... – Containing or obtained from echinacea
Reexamination Certificate
2001-03-02
2002-04-30
Tate, Christopher R. (Department: 1651)
Drug, bio-affecting and body treating compositions
Plant material or plant extract of undetermined constitution...
Containing or obtained from echinacea
C514S557000
Reexamination Certificate
active
06379716
ABSTRACT:
FIELD OF THE INVENTION
Use of echinacea to reduce irritation and boost anti-aging efficacy of cosmetic compositions containing hydroxy acids.
BACKGROUND OF THE INVENTION
Some ingredients used in topical products are potentially irritating, especially to people with “sensitive skin.”
As an example, hydroxy acids (HAs) have been proven to deliver cosmetic benefits, such as improvement in the appearance of photodamaged or naturally aged skin, skin lightening, treatment of age spots, etc. Unfortunately, their use at high concentrations may occasionally be associated with skin irritation, e.g. skin redness and stinging sensation upon application. The irritation can be ameliorated by lowering the amount of an active ingredient in the composition or by reducing the active's penetration through the skin. A serious drawback of both approaches is that the efficacy is impaired. The HA related irritation can be reduced by raising the composition's pH but this method yields reduced efficacy due to a decreased HA penetration through the skin. It is desirable to reduce or eliminate the irritation potential of HAs while maintaining their efficacy.
The need exists, therefore, for a composition and method that prevents or reduces the skin irritation which may be caused by hydroxy acids.
U.S. Pat. No. 5,705,170 (Kong et al.) discloses an herbal cellulite treatment and a cosmetic composition which may contain from 0.1 to 20% wt. of an alpha hydroxy acid. The composition has a pH of from 3-6; echinacea extract is used in the example at a level of 2%. U.S. Pat. No. 5,667,791 (Hersh et al.) discloses a topical composition which may be in the form of a lotion, cream, oil or gel. One of the exemplified compositions contains 0.047% of echinacea and 0.018% of lactic acid. The compositions are used to reduce and repair X-ray radiation induced skin damage. U.S. Pat. No. 5,804,168 (Murad) discloses a composition which may be in the form of cream, paste, gel or ointment or emulsion and may be applied topically for treatment of sun-damaged skin. The composition may contain echinacea and lactic acid. The latter is used in the example at the level of 5.6% wt.
SUMMARY OF THE INVENTION
The present invention provides a method for reducing skin irritation caused by the topical application of a composition containing HAs, the method comprising topically applying echinacea extract. Echinacea extract may be co-present with HAs in the same composition, or may be applied from a separate composition.
According to the present invention, by virtue of topical application of echinacea extract, the skin irritation caused by HAs is reduced or eliminated.
Furthermore, it has been found according to the present invention that echinacea has an additional valuable effect of significantly boosting the anti-aging efficacy of HAs. Thus, when echinacea extract is present in the composition, HAs can be used in a lower amount, without reduction in efficacy, and thus reducing skin irritation potential even further.
The present invention also includes a cosmetic skin care composition containing HAs and
Echinacea purpurea
or
Echinacea pallida.
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 composition, unless otherwise specified.
Echinacea extract is employed in the inventive compositions to reduce or eliminate the skin irritation caused by HAs and/or to boost anti-aging effect of HAs. Echinacea extract, also known as Coneflower extract, can be purchased from commercial suppliers such as BioBotanica. Echinacea extract is used in the inventive compositions and methods in a concentration of from 0.1 to 20%; preferably from 0.5 to 10%, most preferably from 0.5 to 5%.
Echinacea extract may be obtained from the following echinacea species:
Echinacea angustifolia, Echinacea purpurea, Echinacea pallida. Echinacea purpurea
is preferred according to the present invention since it contains chicoric acid, which was shown, as part of the present invention to have anti-irritant activity.
Echinacea purpurea
is also commercially available.
Echinacea pallida
also contains chocoric acid, but it is not commercially available.
The hydroxy acid can be chosen from alpha-hydroxy acids, beta-hydroxyacids (e.g. salicylic acid), other hydroxycarboxylic acids (e.g., dihydroxycarboxylic acid, hydroxy-dicarboxylic, hydroxytricarboxylic) and mixtures thereof or combination of their stereoisomers (DL, D or L).
Preferably the hydroxy acid is chosen from alpha-hydroxy acids having the general structure (1)
where M is H or a saturated or an unsaturated, straight or branched hydrocarbon chain containing from 1 to 27 carbon atoms.
Even more preferably the hydroxy acid is chosen from lactic acid, 2-hydroxyoctanoic acid, hydroxylauric acid, glycolic acid, and mixtures thereof. When stereo isomers exist, L-isomer is most preferred.
It is to be understood that depending on the pH of the composition, the hydroxy acid may be present as a salt, e.g. ammonium or potassium or sodium salt.
Although echinacea extract may be included into compositions that have any pH in the general range of 2.5 to 10, the inventive methods are particularly useful when compositions are at an acidic pH (especially if they contain a hydroxy acid), preferably 3-5 and most preferably at a pH of 3-4, because such compositions are particularly irritating.
A particular advantage of the inventive methods is that higher amounts of hydroxy acids may be employed without causing skin irritation. Preferably the amount of the hydroxy acid component present in the composition is from 0.01 to 20%, more preferably from 2 to 12% and most preferably from 4 to 12% by weight.
Glycolic acid and/or lactic acid are most preferred because although these ingredients have been found to cause irritation, they were found to be particularly efficacious at delivering cosmetic benefits.
The compositions and methods according to the invention also comprise a cosmetically acceptable vehicle to act as a diluent, dispersant or carrier for the active ingredients in the composition, so as to facilitate their distribution when the composition is applied to the skin.
Vehicles other than water can include liquid or solid emollients, solvents, humectants, thickeners and powders. An especially preferred nonaqueous carrier is a polydimethyl siloxane and/or a polydimethyl phenyl siloxane. Silicones of this invention may be those with viscosities ranging anywhere from about 10 to 10,000,000 centistokes at 25° C. Especially desirable are mixtures of low and high viscosity silicones. These silicones are available from the General Electric Company under trademarks Vicasil, SE and SF and from the Dow Corning Company under the 200 and 550 Series. Amounts of silicone which can be utilized in the compositions of this invention range anywhere from 5 to 95%, preferably from 25 to 90% by weight of the composition. The amount of vehicle may range from about 2 to about 99 wt %, preferably from about 50 to about 99%, most preferably from about 80 to 99%, by weight of the total composition.
According to the present invention, the vehicle is preferably at least 60 wt. % water, by weight of the vehicle. The inventive compositions are preferably oil-in-water emulsions, in order to improve dermal delivery of hydroxy acids (See Sah A., “An in-vitro study of the effect of formulation variables and product structure on the delivery of alpha-hydroxy acid (Lactic acid) to skin”, MS Thesis, Department of Pharmaceutical Sciences of the College of Pharmacy, University of Cincinnati, Ohio, July 1996). Such improved delivery is frequently accompanied by increased irritation/sting, making the use of echinacea extract in such emulsions particularly critical. In the preferred oil-in-water emulsions according to the present invention, water comprises at least
De Florio Victor
Harichian Bijan
Palanker Laura Rose
Santhanam Uma
Weinkauf Ronni Lynn
Plotkin Ellen
Tate Christopher R.
Unilever Home & Personal Care USA a division of Conopco, Inc.
Winston Randall
LandOfFree
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