Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Reexamination Certificate
2000-09-19
2002-06-11
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
C424S400000, C424S401000, C514S861000, C514S863000
Reexamination Certificate
active
06403123
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the treatment of dermatological disorders, including psoriasis and eczema. Specifically, the present invention relates to a method of treating anthralin-responsive dermatological disorders by a method of topical application of anthralin that results in minimal or no staining of skin or clothing.
In human skin, certain inflammatory disorders, such as psoriasis, eczema and other dermatoses, may involve a disturbed keratinization with scale formation. The causes of most inflammatory dermatoses are unknown, although immunologic and genetic factors appear to be involved in the development of these diseases. Psoriasis is a chronic inflammatory skin disease characterized by persistent erythema and silvery scales, and remains a disfiguring and disabling cutaneous impairment to millions of people. In the United States, the disease affects approximately 2% of the population. Eczema is also a chronic skin disease and is characterized by persistent itch with erythema and some scales. Since the etiologies of these diseases are unknown, preventions remain inconceivable, and known therapies are empiric.
In psoriasis, photochemotherapy with psoralens plus UVA and systemic treatments with well-known drugs or experimental agents provide short-term remission of the disease. Such drugs include methotrexate, cyclosporin, retinoids, fumaric acid esters, glucocorticoids, liarozole, tacrolimus, anti-CD4-antibodies, interleukin, diphtheria fusion toxin and ascomycin derivatives. Treatment using these drugs can result in immunosuppression, leading to serious infections, cancers, acute and chronic toxicity on liver, kidney and bones, etc. Thus, clinicians have shifted their focus to external or topical treatment of psoriasis, eczema and similar dermatological disorders.
Topical treatments with tar, tazarotene, glucocorticoids or vitamin D
3
analogues, such as calcipotriene, have provided various degrees of temporary remission. However, use of these compounds can be associated with degrees of tachyphylaxis, non-responsiveness and/or rebound worsening.
Anthralin, also known as dithranol, was introduced for topical use in 1916 and continues to be in use for topical treatment of psoriasis and eczema because of its efficacy and safety profile. Anthralin is chemically identified as 1,8,9,-anthracenetriol or 1,8-dihydroxyanthrone, and has a molecular weight of 226 (C
14
H
10
O
3
). Anthralin is known to be effective topically in the treatment of psoriasis, chronic eczemas, dermatophytoses, alopecia areata, and other skin disorders. In topical treatment of psoriasis with anthralin, substantial clearing of chronic plaques usually occurs within two months, and the duration of improvement is decidedly longer than that following topical corticosteroids.
Two undesirable side effects are presently associated with the topical use of anthralin: (1) skin irritation; and (2) staining of the skin, clothing and other items which come in contact with treated areas of the skin. The skin irritation from anthralin is dose-related; therefore, in order to minimize irritation, low concentrations of anthralin are preferable. The second side effect, staining, has, up to the present time, been less manageable. When commercially available products are used for topical treatment of psoriasis or eczema, anthralin can stain the skin and hair various colors ranging from brownish, greenish, to purple colors depending on factors such as pH and the composition of the vehicle by which the anthralin is administered. Removal of the stains from pillowcases, bed sheets and clothing is very difficult, and usually impossible. These adverse effects have discouraged topical use of anthralin products for the treatment of psoriasis, eczema and other dermatoses.
Previously, we have discovered that dithranol (anthralin) for use in the treatment of dermatological disorders may be protected from oxidation when it is present in a composition containing either an antitoxidant alpha hydroxyacid or oxalic acid. Such compositions and methods are disclosed in detail in U.S. Pat. Nos. 4,287,214 and 4,367,224. Although the compositions and related methods of these patents describe compositions for topical application of anthralin to the skin, the problem of staining of the skin, linens or clothing by the anthralin is not addressed.
BRIEF SUMMARY OF THE INVENTION
We have discovered that the staining of the skin and clothing incidental to the topical use of anthralin can be averted or minimized by a simple method of application.
By use of the method of the present invention, anthralin-responsive dermatological disorders can be treated using anthralin with minimal or no staining to the skin, linens and clothing. Specifically, the invention provides a method of treating dermatological disorders in a human comprising: (a) topically applying an anthralin formulation containing a therapeutically effective amount of anthralin to the involved area of the skin of the human, and (b) topically applying a wax formulation to the involved area, wherein the wax formulation comprises a wax. The topical application of the anthralin formulation may be in the form of a liquid, a gel, a lotion or a cream.
The anthralin is present in the anthralin formulation in a concentration of about 0.05% to about 10% by weight. In the most preferred aspects of the invention, anthralin is resent in the anthralin formulation in a concentration of about 0.1% to about 5% by weight, ore preferably about 0.1% to about 1% by weight.
Wax provided for use in the wax formulation of the method of the present invention may be preferably selected from the group consisting of beeswax, ceresin, paraffin and mixtures thereof. The wax formulation, in addition to comprising a wax, may also comprise a wax vehicle.
According to the present invention, wax is present in the wax formulation in a concentration of about 1% to about 80% by weight, preferably about 5% to about 60% by weight, or, more preferably, about 10% to about 40% by weight.
The method of the present invention preferably further comprises the step of topically applying a powder to the involved skin area. This powder may be selected from the group consisting of talc, starch powder, cellulose powder, and oatmeal powder and mixtures thereof.
As used herein, a “therapeutically effective amount” of anthralin is that amount of anthralin that is sufficient to provide a beneficial effect on the dermatological disorder(s) of the patient to whom it is administered.
As used herein, “dermatological disorder(s)” means skin diseases including psoriasis, eczema and other anthralin-responsive skin disorders.
As used herein, “treating” means applying or administering a medication to an area affected by a dermatological disorder in order to improve and/or irradiate the dermatological disorder(s) and/or the symptoms of the dermatological disorder.
As used herein, the term “wax formulation” is meant to encompass compositions having substantially 100% wax by weight, mixtures of wax combined with a solvent or solvents or other dermatologically acceptable vehicles, and/or wax combined with other additives such as cholesterol, mineral oil, lemon oil, vanillin, coconut oil, emulsifiers such as polysorbate 80 and sorbitan sesquioleate.
DETAILED DESCRIPTION OF THE INVENTION
Anthralin for use in the anthralin formulation of the present invention may be provided in any form known in the art, including solution, gel, lotion and powder form. Anthralin may be present in the anthralin formulation in any therapeutically effective amount; however the preferred concentration is in the range of about 0.01% to about 50% by weight or about 0.05% to about 10% by weight. Alternatively, preferred concentrations are in the range of about 0.1% to about 5% by weight, more preferably about 0.1% to about 1% by weight.
The anthralin formulation for use in the method of the present invention may take the form of a liquid, a gel, a cream, a lotion or the like. The anthralin may be dissolved in a solvent in order to form a liquid anthralin
Scott Eugene J. Van
Yu Ruey J.
Akin Gump Strauss Hauer & Feld L.L.P.
Evans Charesse L.
Page Thurman K.
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