Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1998-09-10
2001-10-09
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C514S474000, C514S781000, C514S844000
Reexamination Certificate
active
06299889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field Of The Invention
The present invention relates generally to stable ascorbic acid compositions that are homogeneous solutions suitable for topical use. More specifically, the present invention relates to homogeneous cosmetic preparations incorporating stabilized ascorbic acid that can be topically applied to human skin to impart beneficial appearance effects thereto.
2. Description Of The Prior Art
It is well known that ascorbic acid, synonymously referred to herein as Vitamin C, is essential to the maintenance of a healthy and attractive skin appearance in humans. Vitamin C helps to stimulate and regulate the production of collagen in human skin tissue thus retarding the formation of wrinkles and helping to maintain a healthier and younger looking appearance. Vitamin C also helps to minimize lipid oxidation and cellular damage resulting from prolonged exposure to the sun's ultraviolet rays. By doing so, it counteracts premature aging of the skin. It is generally believed that ascorbic acid inhibits the formation of melanin that can lead to skin discoloration during the aging process, and inhibits the release of histamine from cellular membranes that can lead to allergenic reactions, particularly among individuals with sensitive skin.
Because of these many beneficial effects, it has long been desired to deliver effective concentrations of ascorbic acid percutaneously and directly to the underlying tissue matrix of the skin, i.e. the dermal layer, via a topically applied and cosmetically elegant carrier or base.
Ascorbic acid is appreciably soluble in water. However, it oxidizes rapidly in aqueous solutions. Therefore, it cannot be stabilized in such a medium at the sufficiently high concentrations required to achieve the desired appearance enhancement effect on the skin. On the other hand, solubility of ascorbic acid in non-aqueous media is quite limited so that a large amount of a solvent, such as ethanol, is required to dissolve limited amounts of ascorbic acid. Thus, the limited solubility of ascorbic acid has, heretofore, prevented anhydrous and low water systems from achieving ascorbic acid concentration and efficacy levels required for producing the above described appearance enhancement effect. For this reason, ascorbic acid has been heretofore used in cosmetic formulations only in relatively low concentrations. As a result, prior attempts to develop and to market acceptable cosmetic formulations containing efficacious concentrations of stabilized ascorbic acid have generally met with limited success.
Ascorbic acid is unstable in the presence of oxygen and is rapidly oxidized to dehydroascorbic acid. In body cells, glutathione can reverse the ascorbic acid dehydroascorbic acid conversion so that a pool of ascorbate distributed throughout the body can be maintained.
Aside from preventing scurvy, ascorbic acid is essential to many body or biological functions. The most notable function is the synthesis of collagen, the major fibrillar component of dermal connective tissue, comprising approximately 70 to 80% of the dry weight of the dermis. The essential role of ascorbic acid in the formation and maintenance of collagen as well as in other biological functions and processes has been summarized in U.S. Pat. No. 4,983,382 to Wilmott, et al, which is owned by the assignee of the present invention. The contents of U.S. Pat. No. 4,983,382 are incorporated herein by reference.
U.S. Pat. No. 4,983,382 suggests that replenishing dermal tissues with ascorbic acid percutaneously delivered through the stratum corneum can impart beneficial appearance effects to the skin, including improved tone and luster, a decrease in fine lines and wrinkles, and improved elasticity. However, the compositions disclosed in that patent have ethanol at a concentration of at least forty percent. These compositions do not exhibit sufficient stability to maintain high levels of ascorbic acid concentrations for sufficiently long periods of time. Therefore, they do not generally possess the performance level necessary for the above mentioned skin appearance enhancement effect in cosmetic formulations. To overcome this shortcoming, it is recommended in U.S. Pat. No. 4,983,382, described above, and also in U.S. Pat. No. 5,140,043, to Darr, to store the cosmetic formulation samples in bottles that are impervious to ultraviolet light and to preferably provide with a headspace containing an inert gas.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a stable ascorbic acid composition that contains high levels of ascorbic acid but does not require high levels of water to produce homogeneous solutions.
It is another object of the present invention to provide a stable ascorbic acid composition that contains high levels of ascorbic acid and lower levels of ethanol than used in the prior art, to produce homogeneous ascorbic acid solutions.
It is a further object of the present invention to provide a process for preparing a homogeneous ascorbic acid composition.
It is still a further object of the present invention to provide a method of improving the appearance of skin using the stable ascorbic acid composition of the present invention.
The composition of the present invention basically comprises: (a) ascorbic acid; (b) a polyhydric alcohol; (c) an organic carbonate; and (d) water. The composition of the present invention may further comprise: (e) a monohydric alcohol and/or (f) a hydroxyalkyl cellulose.
The present invention further includes a process for preparing a homogeneous ascorbic acid composition, comprising: preparing a mixture of the ingredients of the above composition, and thereafter, optionally filtering the prepared composition to remove insoluble particles, if present.
The present invention still further includes a method of improving the appearance of skin using the stable ascorbic acid composition of the present invention. The method comprises topically applying the ascorbic acid composition to an area of skin to be affected such that said ascorbic acid is percutaneously absorbed by said skin and thereafter, optionally applying a moisturizer to said area of skin.
Against the foregoing background, it has been discovered that ascorbic acid can be stabilized indefinitely in a composition adapted to topical application to the skin. In the composition, it is desired to achieve as high an amount of ascorbic acid as possible yet maintain the solubility and stability of the ascorbic acid in the composition. Accordingly, the composition should have as little water as possible in order to achieve the stability desired. In addition, ethanol should be minimized to avoid adversely effecting the ascorbic acid concentration.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As used herein the terms “solution”, “preparation”, “composition”, and “compositions” are to be used interchangeably. The terms “cosmetic”, “cosmetic preparation” and “cosmetic composition” include articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced onto, or otherwise applied to the human or animal body or any part thereof for cleaning, beautifying, promoting attractiveness or altering the appearance. They also include articles intended for use as a component in sun screening compositions, medicinal and first aid creams and the like.
In accordance with the present invention, ascorbic acid is stabilized in a cosmetic composition adapted for topical application onto human skin. As a suitable vehicle for the ascorbic acid, a stable composition is provided having desirable cosmetic qualities, namely, an agreeable, pleasant feel and appearance when topically applied to skin. The organic ingredients are preferably selected to produce a cosmetically elegant formulation that facilitates rapid percutaneous absorption of the stabilized ascorbic acid contained therein when topically applied to the skin, whereupon beneficial effects resulting in enhanced skin appearance may be achieved.
The stable composition or compositions according to the present invention are homogene
Cowton Lorraine M.
Duffy John A.
Duggan Michele C.
Avon Products Inc.
Channavajjala Lakshmi
Ohlandt Greeley Ruggiero & Perle LLP
Page Thurman K.
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