Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2000-05-04
2002-06-25
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
Reexamination Certificate
active
06410036
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to cosmetic compositions. More specifically, the invention relates to cosmetic compositions containing relatively high levels of active components that cause substantially no irritation to the skin.
BACKGROUND OF THE INVENTION
The presence of biologically active ingredients in cosmetics has become commonplace today. Such materials provide the consumer with considerable benefits, such as exfoliation, lightening of abnormal pigmentation, lipid barrier repair, and the like, in addition to the more traditional benefits of moisturizing. With the biological benefits, however, sometimes comes the problem of irritation. While most potential users can readily appreciate the advantages of these materials with no problem, certain active ingredients can cause discomfort to individuals with particularly sensitive skin, thereby depriving that segment of the population of the benefits of these products.
One of the most common groups of compounds to which a certain segment of the population reacts is acids, particularly hydroxy acids, or retinoic acid, which have provided enormous benefits to those who are not sensitive to them. These compounds are highly effective keratolytic agents, that effectively bring about exfoliation of dead keratinocytes, reducing the appearance of fine lines and wrinkles, and conferring a smooth, glowing look to the facial skin. However, because of the possibility of irritation, particularly at higher concentrations, these compounds have not reached their full potential in cosmetic compositions, generally having to be used at lower levels than would be optimum for activity. Thus, there continues to be a need for formulations that will permit the exploitation of these compounds to their fullest potential. The present invention fulfills such a need.
SUMMARY OF THE INVENTION
The present invention relates to eutectic mixtures of a principal acid component and at least one other component selected from the group consisting of a carbohydrate, a polyol, a carbonylic compound, an amino acid, and a carboxylic acid. The mixtures of the invention are used in anhydrous cosmetic compositions that, when applied to the skin, slowly release the acid in the presence of the skin's moisture, thereby obtaining the benefit of the acid substantially without any irritation. The invention also relates to a method for preparing a eutectic mixture of an acid component and at least one other component selected from the group consisting of a carbohydrate, a polyol, a carbonylic compound, an amino acid, or a carboxylic acid, the method comprising heating the component having the lowest melting point to the temperature at which it melts, dissolving the remaining component or components in the melted component, and allowing the mixture to cool. While the components of the mixtures are solid before combination, when heated and dissolved as described, they remain as a homogeneous liquid when returned to room temperature.
DETAILED DESCRIPTION OF THE INVENTION
The mixtures of the invention provide a non-irritating base for delivery of potentially irritating acids. The mixtures are non-aqueous, so that the acidic character of the acid component, which is only realized in an aqueous environment, is not present in the mixture. In essence, the acid component cannot ionize, so remains undissociated in the mixture, until the mixture is exposed to the moisture of the skin, at which time it is slowly converted to the acid form and released to the skin to provide the benefits achieved by such acids. The mixtures of the invention are referred to as “eutectic mixtures” which for purposes of the present application and claims means an equilibrium phase between two or more components, which equilibrium phase, or mixture, does not have any of the physical characteristics of the individual components. Eutectic mixtures are known in various chemical areas are known, but are ordinarily difficult to create, and to the best of the inventors' knowledge, have not previously been used in cosmetics or pharmaceuticals.
It has now been unexpectedly discovered that it is possible to create such cosmetically and pharmaceutically acceptable eutectic mixtures with biologically active acid components, when they are combined with specified other components under certain conditions. In the present case, the components of the mixture are all solid at room temperature prior to creation of the mixture, but after melting and dissolution of the components, an anhydrous solution results which remains liquid at room temperature without crystallization of the individual components. This is all achieved, in most cases, in the absence of any additional solvent that dissolves both compounds. To be successfully combined, the individual components must be compatible, i.e., each compound must form an intermolecular interaction with the other, so that this interaction will counteract the usual forces that tend to arrange the individual components into their individual crystalline forms. This result is only obtainable, however, when the components are mixed on the molecular level. In the present mixtures, while not wishing to be bound by any particular theory, it is believed that a complex forms between the two or more components, due to hydrogen bonds, or Van der Waals interactions, between the solutes, interfering with each compound's ability to recrystallize, i.e., to return to the solid state, thereby resulting in a liquid mixture of two normally solid compounds at room temperature. Since this is preferably achieved in the absence of the usual solvent, i.e., water, or at least after the removal of water from the mixture, the mixture is substantially anhydrous, and therefore does not produce the ionization conditions needed to release H
+
ions.
It will be recognized that the term “acid” in the present specification and claims is used, for convenience, to refer to both the non-ionized, substantially inert structural acid in the initial mixture, as well as the active, dissociated molecule that exists when the mixture contacts moisture on the skin. The acid that constitutes the principal acid component (referred to as “principal” to distinguish it from the second component which in some cases may also be an acid) of the mixture can be any pharmaceutically or cosmetically acceptable acid, and is preferably one that exhibits some type of biological activity on the skin. Examples of useful acids for the present purpose include, but are not limited to, alpha hydroxy acids, such as glycolic acid, lactic acid, citric acid, malic acid, tartronic acid, tartaric acid, beta hydroxy acids, such as salicylic acid, and retinoic acid.
The second component which forms part of the mixture is a component selected from the group consisting of a carbohydrate, a polyol, a carbonylic compound, an amino acid, and a carboxylic acid. Compounds from each of these groups have been shown to form the desired type of mixture with acids, and while not wishing to be bound by any particular theory, it is believed that, while chemically diverse, compounds in these groups all have the ability to form intermolecular hydrogen bonds, which provide a solvent-type environment conducive to retaining the liquid state of the mixture upon cooling. Examples of useful carbohydrates include, but are not limited to, monosaccharides, such as glucose, galactose and fructose; disaccharides, such as saccharose, lactose, maltose, and trehalose; and polysaccharides, such as low molecular weight dextrins, soluble starch, amylopectin and amylose. Preferably, the polysaccharides are selected from those having no more than twenty carbohydrate units. Polyols, such as sorbitol, 1-thiosorbitol, inositol, mannitol, and polyvinyl alcohol, can also be employed. The second component can also be a carbonylic compound, for example, ketones or aldehydes, such as dihydroxyacetone or erythrulose, or any amino acid(natural or synthetic), for example, glycine, alanine, valine, norvaline, leucine, norleucine, aspartic acid, glutamic aci, asparagine, gl
De Rosa Mario
Rossi Mose
Dees Jose′ G.
E-L Management Corp.
Lowney, Esq. Karen A.
LandOfFree
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