Formulations and methods for reducing skin irritation

Details Formulations and methods for reducing skin irritation Formulations and methods for reducing skin irritation

1997-06-23

2002-09-24

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Inorganic active ingredient containing

Heavy metal or compound thereof

C424S401000, C424S065000, C424S068000

Reexamination Certificate

active

06455076

ABSTRACT:

TECHNICAL FIELD
This invention relates to compositions and formulations, and methods for using the same, to inhibit skin irritation in animals.
BACKGROUND
Many substances are applied topically to the skin or mucous membranes of humans or animals (hereafter “skin”) in order to alter the subject's appearance, to protect the subject from the environment, or to produce a biological change in the skin or other tissue for therapeutic, preventive or cosmetic purposes. These substances may generically be termed “topical products” and include such topically applied substances as cosmetics, over-the-counter and prescription topical drugs, and a variety of other products such as soaps and detergents.
Topical products occur in a variety of forms, including solids, liquids, suspensions, semisolids (such as creams, gels, pastes or “sticks”), powders or finely dispersed liquids such as sprays or mists. Examples of topical products commonly classified as “cosmetics” include skin care products such as creams, lotions, moisturizers and “treatment cosmetics” such as exfoliants and/or skin cell renewal agents; fragrances such as perfumes and colognes, and deodorants; shaving-related products such as creams, “bracers” and aftershaves; depilatories and other hair removal products; skin cleansers, toners and astringents; pre-moistened wipes and washcloths; tanning lotions; bath products such as oils; eye care products such as eye lotions and makeup removers; foot care products such as powders and sprays; skin colorant and make-up products such as foundations, blushes, rouges, eye shadows and liners, lip colors and mascaras; lip balms and sticks; hair care and treatment products such as shampoos, conditioners, colorants, dyes, bleaches, straighteners and permanent wave products; baby products such as baby lotions, oils, shampoos, powders and wet wipes; feminine hygiene products such as deodorants and douches; skin or facial peels applied by dermatologists or cosmeticians; and others. Examples of topical products commonly classified as “topical drugs” are many and varied, and include over-the-counter and/or prescription products such as antiperspirants, insect repellents, sunscreens and sunburn treatments, anti-acne agents, antibiotics, topical respiratory agents, ocular drugs such as eyedrops and saline solutions, therapeutic retinoids, anti-dandruff agents, external analgesics such as capsaicin products, topical contraceptives, topical drug delivery systems, gastrointestinal agents such as suppositories, enemas and hemorrhoid treatments, reproductive system agents such as vaginal treatments, oral treatments such as lozenges, and many other products with therapeutic or other effects. Other topical products include hand, facial and body soaps and detergents and other forms of skin cleansers, as well as household detergents and many other household products such as solvents, propellants, polishes, lubricants, adhesives, waxes and others which are either applied topically or are topically exposed to the body during normal use.
In a large number of cases, topical products contain chemicals which may produce “irritation,” including various inflammation symptoms or signs, when applied to the skin or mucosa (“skin”). The present invention is directed in part to compositions and methods for inhibiting the irritation associated with such topical products.
The occurrence, frequency and nature of topical-product-induced irritation often varies from user to user. The severity of irritation to the susceptible user may range from subclinical to mild to severe. Typical symptoms of “irritation” include itching (pruritus), stinging, burning, tingling, “tightness,” erythema (redness) or edema (swelling). The irritation response may be due to the direct effect on the skin of certain topical product chemicals or to a response by the immune system directed toward the chemicals alone or in combination with skin components (e.g. antigens).
The sensation of itch is one of the most common skin problems experienced by humans and animals. Itch can be defined as a sensation which provokes the desire to scratch the site from which the sensation originates. All skin contains sensory nerves which can transmit itch or other sensory impulses in response to chemical irritation, environmental exposure or disease processes. Although the precise population of itch producing nerves have not been identified, the thinnest, unmyelinated nerve population, termed type C nociceptive neurons are thought to be the most important in producing the sensation. Itch: Mechanisms and Management of Pruritus. Jeffrey D. Bernhard. McGraw-Hill, Inc. (San Francisco, 1994), pp. 1-22. The sensory nerves of the skin can be considered to be a “final common pathway” for the many irritating conditions which may be ultimately sensed as itch including chemical exposure, environmental exposure (such as that which produces dry, itchy skin) and disease processes such as atopic dermatitis. Many chemical substances are able to produce itch or other sensory impulses when topically applied to the skin. No matter what the ultimate cause of itch, the sensation experienced is the same and provokes the desire to scratch.
Many ingredients used in topical products are known irritants or are potentially irritating, especially to people with “sensitive skin”. These irritating ingredients include fragrances, preservatives, solvents, propellants and many other ingredients that might otherwise be considered inert components of the products. Additionally, many topical product active ingredients, including chemicals that may also be classified as drugs, produce irritation when applied to the skin. These include, but are not limited to, such ingredients as exfoliants and skin cell renewal agents, anti-acne drugs, antiperspirant compounds, antihistamines, anti-inflammatory agents, skin protective agents, insect repellent chemicals, sunscreens and many others. Where more than one chemical irritant is present, their irritating effects may be additive. Furthermore, chemical ingredients may react with one another, or in the environment of the skin, to form new chemicals which are irritating. The vehicles in which the active drug ingredients are formulated may also produce irritation in sensitive people, especially in the case of drugs such as topical corticosteroids.
In addition to chemicals which directly trigger skin irritation, some chemicals indirectly cause the skin to become more sensitive to other chemicals or environmental conditions which would not normally cause irritation. Many chemicals which act as skin “exfoliants” such as retinoids (e.g. tretinoin, retinol and retinal), carboxylic acids including &agr;-hydroxy acids (e.g. lactic acid, glycolic acid), &bgr;-hydroxy acids (e.g. salicylic acid), &agr;-keto acids, acetic acid and trichloroacetic acid, 1-pyrrolidone-5-carboxylic acid, capryloyl salicylic acid, &agr;-hydroxy decanoic acid, &agr;-hydroxy octanoic acid, gluconolactone, methoxypropyl gluconamide, oxalic acid, malic acid, tartaric acid, mandelic acid, benzylic acid, gluconic acid, benzoyl peroxide and phenol, among others, may cause the skin to become more sensitive to irritation triggered by other topically-applied chemicals such as moisturizers, sunscreens, fragrances, preservatives, surfactants (e.g. soaps, shaving cream) and other topical products. Exfoliants and other ingredients may also increase the skin's sensitivity to environmental conditions such as sunlight, wind, cold temperature and dry air, or to chemical agents such as antigens, or may exacerbate the irritation attributable to a pre-existing skin disease.
Conversely, environmental influences may themselves increase the skin's sensitivity to chemicals in topical products by reducing the epidermal skin's “barrier function.” The barrier function acts to minimize absorption or passage of potentially irritating chemicals through the outer “dead” cell layer of epidermal skin into the living skin tissue. Extremes of humidity, for example, can greatly increase irritation from topically-appl

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