Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2002-12-19
2003-11-11
Venkat, Jyothsna (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C514S458000, C514S844000, C514S944000
Reexamination Certificate
active
06645514
ABSTRACT:
BACKGROUND OF THE INVENTION
Human skin is continually assaulted by environmental conditions such as the sun, wind, and pollution. These environmental assaults age the visible layer of skin and reduce. the ability of the skin to serve as an effective barrier layer against the environment. This weathering causes undesirable conditions that include wrinkles, age spots, roughness, scaling, flaking, uneven appearance,.and uneven coloration. In addition, the effects of natural aging also cause the skin to wrinkle.
These negative effects can be prevented, or at least ameliorated, by applying skin care cosmetics that contain skin benefit agents that increase exfoliation according to the present invention.
Human skin may be classified into two major parts: the outer layer or epidermis and an underlying layer or dermis. The dermis contains, among other things, blood vessels, nerves, collagen, elastin, and fibroblast cells, which are responsible for the biosynthesis of collagen and elastin.
The epidermis may be considered to consist of two major zones, an inner or malpighian layer, and an outer or horny layer. The inner malpighian layer, a living tissue, may be further divided into basal, spinous, and granular layers. The outer horny layer, a dead tissue, is also referred to as stratum corneum.
In the natural skin renewal process, basal cells move outward from the basal layer and pass through the spinous and granular layers to become dead cells called corneocytes, in the stratum corneum. This process of forming corneocytes is called keratinization. The stratum corneum consists of approximately 14 layers of dead cells and is the skin tissue that one feels when touching the surface of the skin.
In normal skin, it takes about 14 days for the basal cells to move from the basal layer to the end of the granular layer and to become corneocytes, and another 14 days for the corneocytes to reach the outermost layer of the stratum corneum, where they are naturally shed or exfoliated. Thus, it takes about 28 days for cells of the basal layer to move outward to the surface in the course of skin renewal.
Based on this understanding of skin behavior, two common methods are used to improve the appearance of the skin through the application of topical compositions. In the first, a composition is applied that protects the living portion of the skin from damage. In the second, a composition is applied that increases the natural exfoliation rate (cell renewal rate) of the skin, thus increasing the rate at which the outer layers of dead cells (the stratum corneum) are replaced.
One conventional method of protecting the living skin cells from oxidative damage is by applying a composition containing &agr;-Tocopherol (naturally occurring Vitamin E) to the surface of the skin. Naturally occurring Vitamin E is oil-soluble and can improve the appearance of the skin through continued use by penetrating the outer layers of the skin to protect the living skin cells from oxidative attack, such as from radicals and peroxides. Additional oil-soluble Vitamin E derivatives, including ester derivatized Vitamin E, Tocopheryl Acetate, Tocopheryl Linoleate, Tocopheryl Linoleate/Oleate, Tocopheryl Nicotinate, and Tocopherol (vitamin E alcohol), can also serve to protect living skin cells from oxidative attack. Naturally occurring Vitamin E and its oil-soluble derivatives are believed to improve the appearance of skin by reducing oxidative damage to living cells. These oil-soluble preparations are not known ;to increase exfoliation (skin cell-renewal) rate.
Unlike oil-soluble vitamin E derivatives, water soluble vitamin E derivatives are known to prevent damage to organs when administered internally. U.S. Pat. No. 6,022,867, the entire contents of which is incorporated herein by reference, except that in the event of any inconsistent disclosure or definition from the present application, the disclosure or definition herein shall prevail, describes a water-soluble Vitamin E derivative, DL-&agr;-Tocopheryl Phosphate (VEP). The derivative is prepared by reacting Vitamin E with sodium phosphate. The '867 patent discloses how VEP can improve the health of animals when administered internally. Similarly, WO 93/15731 discloses how internally administering phosphate derivitized Vitamin E to mice can prevent liver damage. Unlike prior oil-soluble Vitamin E preparations, VEP is soluble in water.
Another conventional method to improve the appearance of the skin is to increase the natural exfoliation rate (cell renewal rate) of the outermost part of the stratum corneum, thus exposing lower layers of the stratum corneum, through the application of exfoliating acids. Unlike the previously discussed method of protecting living skin cells with oil-soluble Vitamin E and its oil-soluble. derivatives, here the exfoliating acids speed the; natural exfoliation process by acting on the layers of dead skin cells. Many exfoliating acids are known to increase the rate of natural exfoliation. Exfoliating acids include glycolic acid, lactic acid, citric acid, malic acid, tartaric acid, salicylic acid, acetic acid, pyruvic acid, poly hydroxy acids (including gluconolactone and derivatives) and the alpha and beta hydroxycarboxylic acids that have recently received an increasing amount of attention. The lower molecular weight, short chain acids, such as lactic and glycolic acid, are the exfoliating acids most widely used in cosmetics.
A significant drawback to the use of acids as exfoliating agents, including hydroxycarboxylic acids, is that they are most effective at low pH, about 4.0 or less. As disclosed in Yu, R. J., et al. “Bioavailability of Alpha-Hydroxy Acids in Topical Formulations,” Cosmetic Dermatology, Vol. 9, No. 6 (June 1996), acidic exfoliating agents are believed to deprotonate at a pH of about 3.8, thus losing their beneficial activity at higher pH due to a lack of bioavailability. The inability of exfoliating acids to maintain their effectiveness at higher pH ranges was also demonstrated in Smith, W. P., “Hydroxy Acids and Skin Aging,” Soap/Cosmetics/Chemical Specialties, pp. 54-58, 76 (September 1993).
Another drawback to the use of exfoliating acids is that a strong correlation exists between their ability to exfoliate (increase cell renewal rate) and the degree of skin irritation that results. This increased irritation is likely attributable to the acidity of the active agent. Therefore, for compositions relying on exfoliating acids to increase cell renewal rates, the degree of exfoliation increases with an increase in acidity and irritation. Thus, in actual use, the amount of beneficial skin exfoliation that an exfoliating acid can deliver may not be limited by the exfoliation ability of the acid, but by how often the composition can be applied to the skin without undue irritation.
As previously stated, at a pH of about 4.0 or less, exfoliating acids, which include hydroxycarboxylic acids, demonstrate a significant stimulation of cell renewal coupled with an undesirable level of skin irritation. However, as the pH of the acidic composition is increased to approach neutral (7.0), cell renewal, in addition to skin irritation, rapidly decreases. Thus, it would be beneficial to provide an exfoliating composition that increases the rate of natural skin exfoliation without the skin irritation associated with exfoliating acids. It would be most desirable to provide for enhanced skin exfoliation at a pH more closely approaching neutral to reduce skin irritation. Thee present compositions provide enhanced skin exfoliation at a higher pH and with lower irritation than conventional exfoliating acids, thus overcoming a significant disadvantage of acidic exfoliants.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a cosmetic or dermopharmaceutical composition for topical use comprising a water-soluble Vitamin E derivative and a carrier that includes water. The water-soluble Vitamin E derivative is preferably a water-soluble salt of Vitamin E and is in the water phase.
In another aspect, a water-soluble Vitamin E derivati
Hundey Melissa L.
Schneider Louise M.
Scimeca John V.
Access Business Group International LLC
Brinks Hofer Gilson & Lione
Venkat Jyothsna
LandOfFree
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