Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1998-06-16
2001-03-06
Dudash, Diana (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C514S561000, C514S846000, C514S944000
Reexamination Certificate
active
06197317
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to dermatological compositions and methods for their use. More specifically, the invention relates to dermatological compositions based upon alpha amino acids. Most specifically, this invention relates to dermatological compositions based upon alpha amino acids having a pH in the range of 0.5 to 5.
BACKGROUND OF THE INVENTION
A large variety of materials and compositions have been employed for the topical treatment of skin conditions caused by drying, photodamage, aging, acne and the like. In addition to being effective and safe, any product used for the treatment of skin conditions should be convenient to formulate, easy to use, have long term stability, and be easy to handle. Additionally, such products should preferably be low in cost.
Retinoic acid, and other retinoid compounds are effective for treating acne, wrinkles and other skin conditions. However, these materials can be very toxic and must be used under close medical supervision, and hence are prescription medications. In addition, retinoids are expensive. Strongly corrosive materials such as phenol, mineral acids and halocarboxylic acids such as trichloroacetic acid have been used to treat damaged skin by peeling away the outer layers. These materials must also be used under medical supervision since they can produce serious damage if misapplied.
A number of formulations have been developed for dermatological preparations using alpha hydroxy acids and alpha keto acids. These acids are used at fairly high concentrations, in clinical settings, to produce superficial peeling of the skin. They are also used at lower concentrations by consumers and paraprofessionals to smooth and condition the skin and reduce wrinkles. In many instances, these materials can still be irritating, and as a result compositions have been developed wherein buffering agents such as amphoteric compounds or alkaline materials have been added to the acids to raise their pH. Such compositions are shown in U.S. Pat. Nos. 4,105,782; 4,105,783 and 5,091,171. In other instances, skin care compositions have been formulated utilizing ascorbic acid, and such compositions are shown in U.S. Pat. Nos. 4,983,382 and 5,140,043.
In yet other instances, skin care compositions have been prepared utilizing relatively neutral species such as salts. PCT Patent Application WO96/19182 discloses the use of inorganic salts, primarily of magnesium, manganese and various lanthanide elements for reducing skin irritation. U.S. Pat. No. 5,478,560 discloses the use of salts of mixed amines for treating dry skin.
As can be seen, there is a very large body of prior art directed to topical treatments for various dermatological conditions. The efficacy and safety of the various prior art compositions vary widely as do the cost and ease of formulating and using the compositions. Thus, there is still a need for a composition for treating dermatological conditions, which composition is effective, safe, easy to formulate and use and low in cost. As will be described hereinbelow, the present invention provides a composition which has very good utility for treating skin conditions associated with dryness, aging, photodamage such as photopigmentation and keratoses as well as acne and seborrheic keratoses. These and other advantages of the present invention will be apparent from the discussion and description which follow.
BRIEF DESCRIPTION OF THE INVENTION
There is disclosed herein a composition for the treatment of skin. The composition is based upon alpha amino acids and has a pH in the range of 0.5 to 5. Some of the preferred acids comprise alpha amino dicarboxylic acids, with aspartic and glutamic acid being some particularly preferred acids. In particular embodiments of the invention, the compositions further include a strong acid which functions to solubilize the alpha amino acid, and the composition may further include a basic material for the purpose of adjusting the pH to the preferred range of 0.5 to 5. The compositions of the present invention may also include ascorbic acid as well as inorganic salts, which most preferably comprise a mixture of salts obtained from the Dead Sea.
The present invention also concerns a method for formulating the therapeutic compositions, and in accord with the method, an alpha amino acid is dissolved in a solvent system which includes a strong acid, and this strong acid is neutralized so as to adjust the pH of the solution to the preferred range of 0.5 to 5. Also within the scope of the present invention is a method for treating skin which comprises applying the compositions of the present invention to the skin. The present invention also is directed to a base for a dermatological composition which comprises ascorbic acid and a mixture of inorganic salts of alkali and/or alkaline metals in a carrier. The base may further include urea.
DETAILED DESCRIPTION OF THE INVENTION
In accord with one aspect of the present invention, it has been found that certain amino acids have a very beneficial therapeutic effect on the skin. The compositions of the present invention improve the tone and texture of the skin and decrease wrinkling due to drying and aging. The compositions also decrease photodamage to the skin such as photopigmentation and solar keratoses, and the compositions also operate to remove or decrease the severity of acne and seborrheic keratoses. Among the preferred amino acids are the alpha amino acids and within the context of this disclosure it is to be understood that alpha amino acids are those acids in which the amine group is on the carbon which is alpha to the carboxylic acid moiety. In general, alpha amino acids have the formula set forth hereinbelow:
Wherein the R groups are independently alkyl, aryl, heterocycles, or hydrogen. It is believed that the alpha configuration results in a beneficial chemical interaction between the amino acid and the skin.
Among some of the most preferred alpha amino acids are the alpha amino dicarboxylic acids. As will be understood by those of skill in the chemical arts, alpha amino dicarboxylic acids are those amino acids having two carboxyl groups, and in which the amine group is alpha to at least one of the carboxyl groups. Two of the particularly preferred alpha amino dicarboxylic acids which may be employed in the practice of the present invention are aspartic acid, shown at Formula 2 hereinbelow, and glutamic acid, shown at Formula 3 hereinbelow.
It is to be understood that these amino acids may be also present as salts or ions.
The materials of the present invention are of very low toxicity, and are relatively nonirritating to the skin; hence, they may be used in very high concentrations. However, it has been found that in most instances, amino acid concentrations ranging up to 20%, by weight, are generally effective. In those situations where the composition is being employed in a clinical setting, and particularly when keratoses and other such conditions are being addressed, relatively high concentrations of the composition will be employed. In those instances where the material is being utilized in a nonclinical setting and/or relatively minor conditions are being treated, lower concentrations will suffice. Typically, concentrations of amino acids in the range of 0.5-20% are employed, with concentrations in the range of 2-3% being sufficient for many treatment plans.
The amino acids of the present invention are disposed in a carrier, which in the simplest case comprises water. In other instances, water or alcohol based lotions as well as creams, ointments, gels and other such pharmaceutically acceptable carriers may be utilized. As is known in the art, carriers may further include fragrances, emollients, coloring agents, preservatives, and the like.
In some instances, the alpha amino acids of the present invention are of relatively low solubility in water, weak acids or alcohol. In addressing this problem, it has been found that further enhancements to the compositions of the present invention may be achieved if the alpha amino acid is
Berman Alysia
Dudash Diana
Gifford, Krass, Groh Sprinkle, Anderson & Citkowski, P.C.
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