Background of the Invention

The present invention relates to topical compositions containing acetylsalicylic acid useful for the treatment and/or prevention of skin conditions such as pseudofolliculitis barbae, razor burn and/or ingrown hair.

Pseudofolliculitis barbae is the clinical name given to the skin condition commonly known as "razor bumps." Generally, this condition is described as the ingrowth of emerged hairs back into the skin at a location adjacent to the follicle from which the hair has emerged. This penetration back into the skin results causes an antigenic foreign body reaction at the point of penetration, resulting in lesions consisting of firm papules and pustules in which the ingrown hair can become buried. Infections can become superimposed upon this basic state, augmenting the inflammatory reaction. Thus, further shaving becomes difficult and painful.

Prior patents relating to the use of acetylsalicylic acid in the treatment of razor bumps include:

US PAT. NO. Title 6,703,009 Topical compositions and methods for treating pseudofolliculitis barbae and ingrown hair 6, 156,299 Topical compositions and methods for treating pseudofolliculitis barbae and ingrown hair

6,001,340 Topical compositions and methods for treating Pseudofolliculitis barbae and ingrown hair

5,034,221 Topical agent and method for the treatment of Pseudofolliculitis barbae

Each of the foregoing patents is incorporated by reference herein in their entirety for all purposes.

Summary of the Invention

Among other aspects, the present invention is based on the surprising discovery that the storage shelf life of topical compositions containing acetylsalicylic acid can be significantly increased by providing and/or maintaining an at least substantially water-free composition.

Detailed Description Topical compositions according to the present invention include an active component in a solvent mixture. Each of the components of the composition is generally recognized as safe for topical application to the skin and/or for cosmetic purposes. The key ingredient in the active component is acetylsalicylic acid. Acetylsalicylic acid is well recognized in the art. It is widely available commercially and, thus, will not be described in detail here.

Acetylsalicylic acid is preferably present in an amount effective to treat and/or prevent skin conditions such as pseudofolliculitis barbae, razor burn and/or ingrown hair. "Treatment," in the context of this invention, includes an improvement in the appearance of a skin condition such as pseudofolliculitis barbae, razor burn and/or ingrown hair.

In this regard, the amount of acetylsalicylic acid is preferably not greater than 13% by weight of the composition. Specific examples of suitable amounts include about 7, about 10 and about 12%. Moreover, one example of a suitable range would include about 6.5 to about 10.5%, with about 7 to about 9.7 % or even to about 10% by weight also being a suitable range.

The acetylsalicylic acid is employed in an at least substantially water- free solvent mixture that would allow for application of the acetylsalicylic acid to the skin. The solvent mixture can include one or more of the following components:

Alkylene glycols such as propylene glycol and/or butylene glycol can optionally be included in the solvent mixture. These components are considered to be a moisturizer and capable of producing a pleasant emollient feel when applied to the skin. A specific example of a suitable amount of this component for this purpose is about 5 to about 17% by weight.

In one example of a suitable embodiment, butylene glycol is employed in an amount of about 10 to about 15% by weight of the composition or even about 11 to about 12% by weight of the composition.

While alkylene glycols are often preferred, other compounds capable of providing moisturizing and emollient feel when applied to the skin, are believed to be useful in the composition. Glycerine (glycerol; glycerin, 1,2,3-propanetriol) is an optional component of the composition. Glycerine is a mild astringent that is believed to increase blood flow to the skin and allows the alkylene glycol to carry the acetylsalicylic acid into the epidermis and hair follicles. However, excessive amounts of glycerine could allow the alkylene glycol to penetrate below the epidermis, which would be undesirable.

Where employed, glycerine is present in an amount of about 1% by weight, with less than about 0.5 percent being preferred.

In addition to glycerine, other mildly astringent compositions that can aid in facilitating the contact of the acetylsalicylic acid and the skin can be employed as an optional component in the composition. Other suitable solvents include alcohols and denatured alcohols. One example of a suitable alcohol is isopropyl alcohol (isopropanol; 2-propanol) that can serve as a bulk solvent for the other ingredients of the composition. Isopropyl alcohol is believed to be capable of dissolving oils and grease thus cleaning the skin and permitting more intimate contact of the other ingredients with the skin. Isopropyl alcohol is less dehydrating to the skin than ethanol, and because it is less polar, it is a better solvent for the acetylsalicylic acid. It is anticipated, however, that ethanol in the composition would not adversely affect the effectiveness of the composition.

In one example of a suitable embodiment, isopropyl alcohol is present in an amount not less than about 50% by weight, with about 70 to about 90 % being suitable and about 75 to about 80 also being suitable. One example of a suitable composition includes about 77 to about 79 % of IPA.

Topical compositions can further optionally include one or more silicone additives. Silicone additives, which can be employed in the inventive compositions, include siloxanes, polysiloxanes, or mixtures thereof. Specific examples of suitable materials include decamethylcyclopentasiloxane, octamethylcyclotetrasiloxane and dimethicone. To this end a variety of siloxanes and polysiloxanes are commercially available. The typical amount of such components is not greater than about 5% by weight, with not greater than 2% by weight also being suitable.

One example of a commercially available silicone for use in the composition is cyclomethicone such as that available from Dow Coming as Dow Coming 245 Fluid No. 540. In one example of a suitable embodiment, cyclomethicone is present in an amount of about 1% by weight.

In addition, the composition optionally includes at least one of diglycerin, and polysorbate 80. Each of these components, when present, is typically present in trace amounts.

As discussed above, the composition is at least substantially free of water. The ability to provide and/or maintain such a formulation can involve at least one of (i) adding no, or virtually no, water to the composition during formulation and (ii) storing the composition under conditions that would at least substantially preclude the ingress of water into the composition during storage.

For (i), it is preferred that the amount of any water included in the formation is not greater than 0.0001 percent, or even not greater than 0.00001 percent. Of course, no water would certainly provide a suitable composition. However, it is believed that the presence of trace amounts of water, e.g., on the order of 0.0001 % would not adversely affect shelf life.

For (ii), it is preferred that the composition be stored in a container made from one or more materials having water barrier properties. Examples of suitable materials include those polymeric materials having a level of water penetration not greater than 0.50 g.mil/lOOsq in.d, with a level not greater than 0.30 g.mil/100 sq in.d or even 0.25 g.mil/lOOsq in.d providing better penetration characteristics. Examples of suitable polymeric materials include molded HDPE (high density polyethylene) and blow-molded PP (polypropylene). Another example of a suitable material for the container is glass.

It is believed that (i) can effectively extend the shelf life of the composition from 3 months to as much as 15 months or even longer, while the use of (ii) can further extend shelf life of the composition to 24 months or even 36 months. Not wishing to be bound by any specific theory, it is believed that the elimination/preclusion of water within the composition can prevent, or at least minimize, the undesirable degradation of the acetylsalicylic acid within the composition.

One example of a suitable formulation comprises:

Isopropyl alcohol 78.0%

Butylene Glycol: 11.0%,

Acetylsalicylic Acid: 9.7%

Cyclomethicone 1.0%

Glycerine: 0.3%

Another example of a suitable formu

Isopropyl alcohol 78.0%

Butylene Glycol: 11.3%,

Acetylsalicylic Acid: 9.7%

Cyclomethicone 1.0%

In preparing the composition, the components can be mixed by any suitable technique, e.g., in a batch process, to dissolve acetylsalicylic acid in the solvent. It has been observed that the typical consumer tends to prefer a product that is homogeneous in appearance and without any appreciable amounts of precipitate, with a precipitate-free composition being preferred from a consumer standpoint. The composition can be stored in containers have any desired shape or size including bottles, and roll-on applicators. Such storage container types are recognized in the art and need not be described in detail here.

The preferred method of use includes the steps of applying the composition to the skin, e.g., a man's face after shaving the beard, or a woman's leg, underarms or bikini lines, using whatever method is preferred. For best results the composition should not be immediately washed off or otherwise removed.