Title: Stabilization of ascorbic acid, ascorbic acid
derivatives and/or extracts containing ascorbic acid for topical use
United States Patent: RE38,623
Issued: October 12, 2004
Inventors: Hernandez; Steven (Blue Point, NY); Shaffer; Burt (Huntington, NY)
Assignee: Topix Pharmaceuticals, Inc. (Amityville, NY)
Appl. No.: 725980
Filed: November 29, 2000
Abstract
A stable composition is provided to treat and/or prevent photo-aged skin and related skin disorders such as sunburn, wrinkles, poor skin tone and skin discoloration by topically applying to the skin the treatment composition containing an effective amount of a compound such as ascorbic acid, derivatives of ascorbic acid and/or extracts containing ascorbic acid, in a pharmaceutically acceptable vehicle containing a substantially anhydrous base having no water added. The anhydrous base stabilizes the compound, so that the compound remains effective for an effective period of time, even in the presence of exposure to water.
BRIEF SUMMARY OF THE INVENTION
In keeping with these objects and others which may become apparent, according to the present invention, a new stable, long-lasting composition is provided as a pharmaceutical delivery vehicle for delivery of ascorbic acid, ascorbic acid derivatives and/or extracts containing ascorbic acid, to prevent and treat sun-damaged and photo-aged skin, and as a preventative and cosmetic for undamaged skin.
A method of preventing and/or treating photo-aged skin, sunburn, wrinkles and related skin disorders is provided by topical application of a lotion, cream, gel or pad applied formulation, preferably a substantially anhydrous composition, with no water added, containing effective amounts of ascorbic acid, ascorbic acid derivatives and/or extracts containing ascorbic acid, for topical application to the affected area of the skin. The composition of the present invention can also be used to prevent photo-aging of the skin.
Ascorbic acid, or its derivatives, such as ascorbic palmitate, sodium ascorbate, potassium ascorbate, ammonium ascorbate, triethanolamine ascorbate, ascorbyl phosphate or magnesium ascorbyl phosphate and related compounds, is applied in a pharmaceutically acceptable vehicle, in a concentration of from 0.1 percent by weight to 95 percent by weight, preferably 10-15 percent by weight, generally by frequent periodic application, such as by a once or twice daily application.
Instead of a substantially water based delivery system, the ascorbic acid, ascorbic acid derivatives and/or extracts containing ascorbic acid are provided in a substantially anhydrous base, with no added water. Because the components have a natural water sub-component, the base is not water free, but is substantially anhydrous, because the pre-existing water concentration does not generally exceed five (5) percent by weight of the total composition. To achieve the substantially anhydrous composition, no water is added, in contrast to the water-based composition in Darr '043.
The substantially anhydrous base protects the ascorbic acid, or its derivatives and/or extracts containing ascorbic acid, from degradation, instability, loss of potency and loss of color.
The topical pharmaceutical delivery vehicle includes a mixture of a base consisting essentially of a substantially anhydrous composition, with no water added, in combination with the ascorbic acid, ascorbic acid derivatives and/or extracts containing ascorbic acid, wherein the substantially anhydrous composition, with no water added, is provided in a range of from 0.1 percent by weight to 99.8 percent by weight, preferably about 30 percent by weight.
In the preferred embodiment, the substantially anhydrous base includes silicone compounds, which provide a unique, cosmetically elegant smooth, lustrous tactile feel when applied to the skin.
Preferably the substantially anhydrous composition, with no water added, includes silicones and derivatives of silicone chemistry. However, other substantially anhydrous composition, with no water added, may be utilized, such as other emollients, emulsifiers, surfactants, oils and waxes, polyols, binders, anti-oxidants or chelating agents.
Other inactive components may include preservatives, humectants, viscosity control aids, pH buffers and carrier solvents. However, certain pH buffers and solvents may also function as a substantially anhydrous base.
The resultant mixture is smooth feeling delivery vehicle which delivers the ascorbic acid or its derivatives to the skin in an effective and stable manner.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with the present invention, a stable, long-lasting composition is provided as a pharmaceutical delivery vehicle for delivery of ascorbic acid to sun-damaged and photo-aged skin.
A method of treating photo-aged skin, sunburn, wrinkles and related skin disorders is also provided by topical application of a lotion, cream, gel or pad applied formulation, preferably a substantially anhydrous composition, with no water added, containing effective amounts of a compound selected from the group consisting of ascorbic acid, ascorbic acid derivatives and/or extracts containing ascorbic acid, for topical application to the affected area of the skin.
Ascorbic acid, or its derivatives, such as ascorbyl palmitate, sodium ascorbate, potassium ascorbate, ammonium ascorbate, triethanolamine ascorbate, ascorbyl phosphate or magnesium ascorbyl phosphate, ascorbic acid polypeptides, ascorbyl glucosamine, ascorbic acid polymers, esters of ascorbic acid, amides of ascorbic acid L-ascorbic acid, known as vitamin C, or other derivatives, or related compounds, including botanical or herbal extracts, such as extracts of acerola, citrus extracts, strawberry, which may supply L-ascorbic acid or its derivatives, is applied in a pharmaceutically acceptable vehicle, in a concentration of from 0.1 percent by weight to 95 percent by weight, preferably 10-15 percent by weight, generally by frequent periodic application, such as by a once or twice daily application.
Instead of a water based delivery system, the compound containing ascorbic acid, ascorbic acid derivatives and/or extracts containing ascorbic acid, is provided in a substantially anhydrous with no water added base without water. The base provides a unique cosmetically elegant topical vehicle which protects the ascorbic acid or its derivatives from degradation, instability, loss of potency and loss of color. The base includes a mixture of a substantially anhydrous composition, with no water added, with the compound, wherein the substantially anhydrous composition is provided in a range of from 0.1 percent by weight to 99.8 percent by weight, preferably about 30 percent.
Preferably, the substantially anhydrous composition, with no water added, includes silicones and derivatives of silicone chemistry, including but not limited to cyclomethicones (volatile silicones), linear silicones, dimethylpolysiloxane, dimethicone copolyols, silicone glycols, aminofunctional silicones, polymeric silicones, silicone waxes, such as high molecular weight dimethicones and silicone derivative waxes.
When various silicone compounds are used, a lustrous, elegant smooth tactile feel is achieved when the topical composition is applied to the skin.
Other substantially anhydrous compositions, with no water added, may be substituted for the silicones, such as other emollients, including but not limited to esters, amides, ethoxylated fats, mineral oil, petrolatum, vegetable fats and animal fats, such as hydrogenated tallow and lanolin.
Substantially anhydrous synthetic waxes, such as triglycerides and tribehin may be utilized. Polyols such as polyhydric alcohols and solvent such as mineral oil, glycerin and propylene glycol and sorbitol may be used.
Emulsifiers such as anhydrous polysorbate and PEG 60 hydrogenated castor oil may be employed, as well as anhydrous surfactants such as nonphenol.
Anti-oxidants, such as BHA, BHT, propylgallate, Vitamin E tocopherol, as well as chelating agents such as disodium EDTA, may also be used to further stabilize other substantially anhydrous bases. However, liquid or non-granular anti-oxidants, may be used as a substantially anhydrous base with ascorbic acid by themselves.
Fat soluble vitamins, such as substantially anhydrous Vitamins A, D and E and their esters or derivatives, may also be used as bases for the ascorbic acid based composition.
Moreover, pH buffers such as alkaline sodium citrate and magnesium citrate are effective as substantially anhydrous bases for the delivery vehicle.
Other inactive components may include preservatives, humectants, viscosity control aids, pH buffers and carrier solvents. However, as noted above, certain pH buffers and solvents may also act as an anhydrous base.
The resultant mixture is a comfortable delivery vehicle which delivers the ascorbic acid, its derivatives or extracts containing ascorbic acid to the skin in an effective and stable manner.
The following examples illustrate topically applied skin care products which can be prepared using conventional procedures from the following ingredients with typical ranges of acceptable percentages by weight and typical preferred percentage by weight shown. The formulations are illustrative only:
Ingredient Range(% w/w) Preferred(% w/w)
Formulation #1:
Ascorbic acid 0.1-95.0 10.0
Cyclomethicone 0.1-99.8 30.0
Water (no water added) 0-5.0 0.0
Surfactant 0-90.0 5.0
Methylparaben (preservative) 0.0-3.0 0.2
Steareth-2 (emulsifier) 0.0-10.0 3.5
Gelene (viscosity aid) 0.0-95.0 36.3
Bentronite (binder) 0.0-25.0 5.0
Formulation #2:
Polyglyceryl methacrylate Gel 0.0-99.0 60.0
Ascorbic acid 0.1-95.0 15.0
Silicone Glycol 0.1-60.0 15.0
Water 0.0 0.0
The present invention therefore includes a method for the prevention and/or treatment of photo-aged skin and related skin disorders, such as wrinkles, sunburn, poor skin tone and skin discoloration.
The method comprises steps of the topical application of suitable compositions containing ascorbic acid, its derivatives or extracts containing ascorbic acid, in a substantially anhydrous base, with no water added.
In general, the treatment composition suitable for use in accordance with the invention containing ascorbic acid, its derivatives or extracts containing ascorbic acid, may be applied in any dermatological acceptable vehicle such as a gel, lotion, cream or pad applied formulation, which may or may not be emulsified and may contain ingredients to improve, modify, or stabilize the formulation physically or cosmetically. Other suitable formulations will be apparent to those skilled in the art.
The treatment compositions of the invention will improve the condition of the skin to which it is applied, preferably by frequent periodical application over an extended period of time without undue irritation to the skin or any other side effects.
Generally, the topical applications are applied periodically such as one or two times per day.
Moreover, Table 1 shows the stability of examples of the composition. Stability tests were conducted of topical skin treatment compositions containing ascorbic acid, specifically L-ascorbic acid at 10%. The compositions were tested for percentage of stability as a function of shelf life in a closed jar at either room temperature or at an elevated temperature of from 40oC. to 45oC. Tests of the containers of the compositions at room temperature were conducted over a six month period and tests of the containers of the compositions at elevated temperature of from 40oC. to 45oC. were conducted over a three month period.
TABLE I
Composition No. 1:
a topical facial complex containing 10% of L-ascorbic acid.
a) Condition: maintained at room temperature in a 1/2 oz.
clear jar with lined cap.
b) Test: ascorbic acid assay.
c) Recommended Percentage of Stability: 80.0%-110.0%
d) Resultant Percentage of Stability:
0 months 3 months 6 months
95.6% 90.1% 90.4%
Composition No. 1:
a topical facial complex containing 10% of L-ascorbic acid.
a) Condition: maintained at 40oC. to 45oC. in a
1/2 oz. clear jar with lined cap.
b) Test: ascorbic acid assay.
c) Recommended Percentage of Stability: 90.0%-110.0%
d) Resultant Percentage of Stability:
0 months 1 month 2 months 3 months
95.6% 91.4% 90.4% 84.5%
Composition No. 2:
a topical hand and body complex containing 10% of
L-ascorbic acid.
a) Condition: maintained at room temperature in a 2 oz.
container.
b) Test: ascorbic acid assay.
c) Recommended Percentage of Stability: 80.0%-110.0%
d) Resultant Percentage of Stability:
0 months 3 months 6 months
98.5% 92.4% 90.2%
Composition No. 2:
a topical hand and body complex containing 10% of
L-ascorbic acid.
a) Condition: maintained at eleveated temperature from
40oC. to 45oC. in a 2 oz. container.
b) Test: ascorbic acid assay.
c) Recommended Percentage of Stability: 80.0%-110.0%
d) Resultant Percentage of Stability:
0 months 1 month 2 month 3 months
98.5% 95.0% 91.1% 84.0%
Other changes to the present invention may be made without departing from the spirit or scope thereof, when read in conjunction with the appended claims.
Claim 1 of 21 Claims
We claim:
1. A topical composition consistently essentially of a mixture of a compound selected from the group consisting of ascorbic acid, derivatives of ascorbic acid and extracts containing ascorbic acid and a substantially anhydrous pharmaceutically acceptable base in an amount of above about 10% by weight of the composition.
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