Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2001-01-30
2004-03-09
Criares, Theodore J. (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C514S561000, C514S557000
Reexamination Certificate
active
06703030
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 acidic amino acids. Most specifically, this invention relates to dermatological compositions based upon carboxylated, acidic amino acids.
BACKGROUND OF THE INVENTION
A large variety of materials and compositions has 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 also been used to treat damaged skin. Such corrosive materials achieve a therapeutical effect by causing the outer layers of skin to peel away. 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.
The parent patent, referred to hereinabove, discloses the fact that certain alpha amino acids (including those referred to as acidic amino acids) are beneficial compounds for the treatment of skin conditions. The parent patent further discloses the use of various acids, including carboxylic acids, to solubilize the amino acid compounds so as to facilitate their incorporation into various dermatological compositions. As will be described in greater detail hereinbelow, it has now been found that when acidic amino acids are solubilized with carboxylic acids, a beneficial interaction occurs which creates a new therapeutic species generally referred to herein as “a carboxylated, acidic amino acid” or a “tricarboxylic acid” or an “amino fruit acid.” This new therapeutic material is highly effective for treating a variety of skin conditions. It has a strong antioxidant action; and, it is most surprising that, the material is very non-caustic to skin even at very low pH levels. 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 carboxylated, acidic amino acids obtained by treating an acidic amino acid with a carboxylic acid. Some of the preferred acidic amino acids comprise alpha amino dicarboxylic acids, with aspartic and glutamic acid being some particularly preferred acidic amino acids. The carboxylic acids used in this invention can include dicarboxylic acids, hydroxy carboxylic acids, halocarboxylic acids and the like.
The present invention also concerns a method for formulating the therapeutic compositions; and in accord with the method, an acidic amino acid is reacted with a carboxylic acid to produce the carboxylated, acidic amino acid. The resultant material is disposed in an appropriate carrier, preferably in an amount sufficient to produce a composition with a pH in the range of 0.5 to 5. Also disclosed are therapeutic methods which employ the composition of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In accord with a first 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 compris
Criares Theodore J.
Gifford, Krass, Groh Sprinkle, Anderson & Citkowski, P.C.
Wells Lauren Q.
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