Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2001-01-25
2002-03-26
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S078030, C514S474000, C514S937000
Reexamination Certificate
active
06361783
ABSTRACT:
TECHNICAL FIELD
The invention pertains to the field of compositions, particularly cosmetic compositions, containing ascorbic acid in bioavailable form.
BACKGROUND OF THE INVENTION
It is well known that aging of the skin is due, at least in part, to continual stretching and contraction of both the dermal and epidermal layers of the skin and disruption of the collagen bundles which provide support to the epidermis. Collagen consists of long elastic polypeptide fibers interconnected by bridges which provide the cohesion and stability of connective tissue. This enables collagen to act as an elastic tissue in every direction and retain water. Collagen aging manifests itself as a break in connection between the collagen fibers. Age, severe weather, and pollution accelerate the breaks and slow down renewal of the collagen structure.
Ascorbic acid, or Vitamin C, has many known biological functions. The L-ascorbic acid isomer is biologically active and is known to stimulate the synthesis of collagen, act as a free radical scavenger, and minimize lipid peroxidation and other forms of cellular damage associated with aging.
Ascorbic acid is a white, odorless, crystalline solid having the empirical formula C
6
H
8
O
6
, a molecular weight of about 176, and exhibits the following structural formula:
Ascorbic acid is highly soluble, but extremely unstable, in water and rapidly decomposes to form dehydroascorbic acid. This degradation is even more pronounced in the presence of oxygen. It is known that ascorbic acid is much more stable in nonaqueous polar solvents such as polyols, but unfortunately its solubility is limited in such solvents and it generally is thought to be not possible to obtain stable ascorbic acid solutions of more than several percent by weight concentration. Since the anti-aging effects of ascorbic acid are known to be dose-dependent, it is desirable to make stable cosmetic compositions containing ascorbic acid dispersed in a cosmetically acceptable carrier at a concentration of greater than about 5 weight percent, preferably up to 20 or 30 weight percent.
Numerous patents and publications teach various ways of stabilizing ascorbic acid. For example, European Patent Publication No. 0 729 746 teaches an ascorbic acid delivery system comprised of a two compartment kit. In the first compartment is an anhydrous solution of ascorbic acid dissolved in a nonaqueous polar solvent such as a polyol. In the second compartment is an alkaline aqueous solution. The contents of the two compartments are mixed immediately prior to use. The more alkaline aqueous solution increases the pH of the anhydrous ascorbic acid containing solution to provide a composition which does not tingle the skin.
U.S. Pat. No. 5,350,773 teaches stable liquid products used for liquid human and animal food. The compositions are in the form of anhydrous emulsions containing a nonpolar fatty material as the dispersed phase and a polar nonaqueous solvent as the continuous phase. Esters of ascorbic acid are used as the emulsifying agent.
U.S. Pat. No. 5,427,814 teaches a method for protecting a fat against oxidation by mixing ascorbic acid into a polar solvent, and adding the mixture to a heated mixture of tocopherol and lecithin. The polar solvent is then evaporated from the mixture by subjecting the mixture to heat for a period of time.
U.S. Pat. No. 5,308,621 teaches a method for transdermal administration of ascorbic acid. Fine particulate ascorbic acid is suspended in a pharmaceutically acceptable carrier such as a polyol. The compositions are topically applied and the particulate ascorbic acid dissolves upon contact with skin and is absorbed into the skin.
European Patent Publication No. 0 755 674 teaches stabilized ascorbic acid compositions containing a water activity value of less than 0.85. The compositions contain a minimum level of water, in addition to a polyol and an oil.
U.S. Pat. No. 5,587,149 teaches ascorbic acid emulsion compositions comprising ascorbic acid solubilized in a polyol as the dispersed phase and oil as the continuous phase.
However, none of the above patents teach a stable anhydrous ascorbic acid containing composition suitable for cosmetic application where high levels of ascorbic acid are solubilized in the composition and remain stable over protracted periods of time. By “solubilized” it is meant either dissolved or emulsified, but not merely suspended.
An object of the invention is to provide a method for stabilizing ascorbic acid to enable its use in cosmetic products which have anti-aging effects.
Another object of the invention is to provide a stabilized ascorbic acid composition suitable for use in cosmetics.
Another object of the invention is to provide a stabilized ascorbic acid composition containing ascorbic acid at significant concentrations.
Another object of the invention is to provide a stabilized ascorbic acid composition in an anhydrous emulsion form which contains ascorbic acid at significant concentrations.
SUMMARY OF THE INVENTION
The invention comprises a composition in the form of an anhydrous emulsion having as a dispersed phase, ascorbic acid dissolved by means of energy input, in a nonaqueous polar organic solvent, and as the continuous phase a nonaqueous nonpolar organic solvent.
The invention comprises a composition in the form of an anhydrous emulsion having as the dispersed phase a nonaqueous nonpolar organic solvent, and as the continuous phase ascorbic acid dissolved in a nonaqueous polar organic solvent.
The invention is also directed to a method for dissolving ascorbic acid in a nonaqueous polar organic solvent, comprising the steps of:
a) heating the nonaqueous polar organic solvent to a temperature sufficient to dissolve ascorbic acid,
b) dissolving particulate ascorbic acid in the heated carrier composition, and
c) reducing the temperature of the mixture, preferably to approximately room temperature.
The invention is also directed to a method for making an anhydrous emulsion having as a dispersed phase ascorbic acid dissolved in a nonaqueous polar organic solvent, and as the continuous phase a nonaqueous nonpolar organic solvent, comprising the steps of:
(a) heating the nonaqueous polar organic solvent to a temperature sufficient to dissolve ascorbic acid,
(b) dissolving particulate ascorbic acid in the heated nonaqueous polar organic solvent,
(c) reducing the temperature of the mixture, preferably to approximately room temperature,
(d) emulsifying the ascorbic acid mixture into the nonaqueous nonpolar organic solvent.
The invention also comprises a method for making an anhydrous emulsion having as the dispersed phase a nonaqueous nonpolar organic solvent, and as the continuous phase ascorbic acid dissolved in a nonaqueous polar organic solvent, comprising the steps of:
(a) heating the nonaqueous polar organic solvent to a temperature sufficient to dissolve ascorbic acid,
(b) dissolving particulate ascorbic acid in the heated nonaqueous polar organic solvent,
(c) reducing the temperature of the mixture, preferably to room temperature,
(d) emulsifying the nonaqueous nonpolar organic solvent into the solubilized ascorbic acid mixture.
The invention is directed to cosmetic compositions comprising, by weight of the total composition:
0.1-50% ascorbic acid,
5-98% of a nonaqueous polar organic solvent,
5-98% of a nonaqueous nonpolar organic solvent.
BACKGROUND OF THE INVENTION
Definitions
The term “ascorbic acid” when used in accordance with this invention means L-ascorbic acid, the bioavailable form, and derivatives thereof.
The term “partition coefficient” when used in accordance with the invention means the octanol/water partition coefficient of the solvent as calculated by the ACD/LogP software program marketed by Advanced Chemistry Development, Inc. The software calculates the partition coefficient based upon the molecular structure of the solvent. Actual chemical measurement of partition coefficients may be difficult. The partition coefficient is defined as, in the equilibrium distribution of the solvent between two liquid phases, one of which i
Guthauser Bernadette
Moaddel Teanoosh
Radice William Joseph
Wolf Barbara Ann
Blackburn Julie
Reulon Consumer Products Corporation
Williamson Michael A.
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