Drug – bio-affecting and body treating compositions – Anti-perspirants or perspiration deodorants
Reexamination Certificate
2002-07-12
2004-12-28
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Anti-perspirants or perspiration deodorants
C424S066000, C424S068000, C424S400000, C424S401000
Reexamination Certificate
active
06835373
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to antiperspirant compositions suitable for topical application to human skin, particularly the axilla. The compositions of the present invention provide an efficacious treatment for perspiration, in combination with desired skin benefits.
BACKGROUND OF THE INVENTION
Antiperspirant actives currently used in the industry are Lewis acids. Typically, such antiperspirant actives are partially neutralized chloride salts of metal ions such as aluminum and zirconium. It is believed that, upon contact with perspiration, these materials enter the sweat duct via diffusion or convection, react with the basic (or less acidic) components of perspiration, and thereby form hydroxide plugs that block perspiration from reaching the skin surface. One route to improving the efficacy of antiperspirant actives is to increase the acidity of the active, as shown by reducing the metal to chloride molar ratio of the active.
Historically, the antiperspirant industry has migrated away from the use of antiperspirant actives having low metal to chloride molar ratios, due to the potential for increased skin irritation associated with their use. This irritation is believed to result from the degrading effect of the low pH (≦3) and high chloride level of these actives on the surface of the skin. Products in which very acidic metal salts (e.g., such as aluminum chloride) are dissolved in alcohol or aqueous solutions have been particularly problematic since, after application, the solvents would evaporate, leaving a thin “crust” of metal salt in direct contact with the skin. These residual metal salts are sensitive to moisture, and upon rewetting by moisture from the skin, produced a concentrated, highly irritating acidic solution contacting the skin surface. Nevertheless, those suffering from hyperhidrosis, or excessive perspiration, have had little choice but to use such irritating products for their efficacy.
One method of decreasing the irritation potential for acidic actives is to increase the glycine to zirconium molar ratio of the active itself, as described in U.S. Pat. No. 6,375,937, Chopra et al., issued Apr. 23, 2002. This approach increases the pH of the active, thus reducing active efficacy. Another known method of reducing the irritation potential for these actives is to encapsulate the active in a product matrix that reduces the interaction between the active and the skin surface. This can be accomplished in a wide variety of ways, including the use of non-volatile solvents, high wax levels, and encapsulation of the active in polysaccharides or starches. Unfortunately, many of the matrix components that have been used to reduce skin irritation also significantly reduce product efficacy by preventing the dissolution of the active in sweat, thereby preventing the active from entering the duct and creating a blockage.
It has now been discovered that the use of non-volatile solvents with low surface tensions reduces the irritation associated with particulate acidic antiperspirant actives having low metal to chloride molar ratios, without reducing product efficacy. It is believed that solvents with low surface tensions spread out rapidly and form a protective layer on the skin and around the active. This protective layer helps to substantially keep the acidic metal salt active particles from coming into direct contact with the skin surface. Furthermore, the protective layer provides a sufficient barrier against penetration by smaller amounts of water (e.g., transepidermal water), while still allowing for penetration by the relatively greater amounts of water produced by sweat glands (e.g., during perspiration). Perspiration easily displaces the low surface tension solvents, thereby allowing effective release of the acidic metal salt active particles from the product matrix during sweating.
SUMMARY OF THE INVENTION
The present invention is directed to antiperspirant compositions comprising a particulate antiperspirant active having a metal to chloride molar ratio of less than or equal to about 1.3; a volatile solvent; a low surface tension non-volatile solvent; and a suspending agent. The present invention is further directed to methods for controlling perspiration and hyperhidrosis through the topical application of the disclosed antiperspirant compositions. The compositions and methods of the present invention provide enhanced antiperspirant efficacy, in combination with reduced skin irritation. These and other features, aspects, and advantages of the present invention will become evident to those skilled in the art from a reading of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
While the specification concludes with claims that particularly point out and distinctly claim the invention, it is believed the present invention will be better understood from the following description.
The present invention relates to antiperspirant compositions comprising a particulate antiperspirant active having a metal to chloride molar ratio of less than or equal to about 1.3, a volatile solvent, a low surface tension non-volatile solvent, and a suspending agent. Each of these elements will be described in detail hereinafter.
The term “ambient conditions,” as used herein, refers to surrounding conditions at about one atmosphere of pressure (1 atm), at about 50% relative humidity, and at about 25° C., unless otherwise specified. All values, amounts and measurements described herein are obtained under ambient conditions, unless otherwise specified.
The term “anhydrous,” as used herein, refers to compositions or materials that contain less than about 5%, more preferably less than about 3%, even more preferably less than about 1%, and still more preferably zero percent, by weight of free or added water, other than the water of hydration typically associated with any particulate solids prior to formulation.
The term “particulate,” as used herein, refers to compositions or materials that are comprised of solid particles and are not dissolved in water or other solvents.
The term “surface tension,” as used herein, refers to the attractive force in any liquid exerted by the molecules below the surface upon those at the surface/air interface, which force tends to restrain a liquid from flowing. The term “low surface tension,” as used herein, refers to liquids having a surface tension of less than or equal to about 30 dynes.
The term “volatile,” as used herein, unless otherwise specified, refers to those materials that are liquid under ambient conditions and which have a measurable vapor pressure at 25° C. These materials typically have a vapor pressure greater than about 0.01 mmHg, more typically from about 0.02 mmHg to about 20 mmHg, and an average boiling point typically less than about 250° C., more typically less than about 235° C.
All cited references are incorporated herein by reference in their entireties. Citation of any reference is not an admission regarding any determination as to its availability as prior art to the claimed invention.
All percentages, parts, and ratios as used herein are by weight of the total composition, unless otherwise specified. All such weights as they pertain to listed ingredients are based on the active level and, therefore, do not include solvents or by-products that may be included in commercially available materials, unless otherwise specified.
The antiperspirant compositions and methods of the present invention can comprise, consist of, or consist essentially of the essential elements and limitations of the invention described herein, as well as any of the additional or optional ingredients, components, or limitations described herein.
Antiperspirant Active
The antiperspirant compositions of the present invention include any particulate antiperspirant active suitable for application to human skin. The concentration of antiperspirant active in the composition should be sufficient to provide the finished antiperspirant product with the desired perspiration wetness and odor control.
The antiperspirant active used here
Kolodzik Martha Jane
Lanzalaco Anthony Charles
Swaile David Frederick
Dodson Shelley A.
Oney Jack L.
The Procter & Gamble & Company
Vitenberg Vlad
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