Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Reexamination Certificate
1999-03-01
2001-07-10
Pak, John (Department: 1616)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
C514S859000, C514S863000, C514S886000, C514S887000, C514S944000, C514S964000, C514S772300, C424S400000, C424S401000, C424S486000
Reexamination Certificate
active
06258830
ABSTRACT:
The present invention generally relates to pharmaceutical preparations and more specifically relates to stable gels for topical treatment of both acne and psoriasis in humans.
Acne is a relatively common inflammatory disease afflicting the skin. The severity of the disease ranges from a more or less superficial disorder to inflammatory conditions in which bacterial invasions occur causing inflamed and infected sacs to appear. Most activity occurs where sebaceous glands are the largest, most numerous and of course most active. Left untreated, the acne lesions may become extensive and leave permanent disfiguring scars.
The cause of acne is increased activity of the sebaceous glands and the epithelial tissue lining the infundibulum. The increased activity of the sebaceous glands produces more sebum which consists of free and esterified fatty acids as well as unsaponifiable lipid components which results in increased skin oiliness.
In inflammatory acne, the initial inflammation of hair follicle walls results from the presence of free fatty acids derived from the sebum. In the presence of bacterial lipolytic enzymes, triglycerides of the sebum are split, releasing the fatty acids. The normal bacterial flora in the sebaceous duct produce the enzymes responsible for splitting the triglycerides.
Current treatments for acne include cymedolytics, exfoliants, oral and topical bacteriostatics, as well as systemic antibiotics. Ideally, topical formulations for the treatment of acne should be compounded with little or no oil in the formulation and should not leave any oil film on the skin to compound the condition.
Psoriasis, on the other hand, is a chronic, hereditary, recurrent papulosquamous dermatosis typically involving the scalp and extensor surfaces of the limbs, especially the elbows, knees and shins. The distinctive lesion of psoriasis is a vivid red macule, papule or plaque covered almost to its edge by silvery lamellated scales. Psoriasis is further characterized by accelerated epidermal proliferation, leading to excessive scaling of the skin due to the fact that psoriatic skin loses water eight to ten times faster than normal skin. For this reason, topical treatment thereto typically contains oils which are best suited for moisturizing the skin.
The present invention is directed to a formulation and a method of producing a formulation in gel form that does not contain any oil and therefore meets the requirements of treatment and also offers a high moisturizing factor for psoriatic treatment. Effectiveness of an active agent for treatment of acne and psoriasis is, of course, dependent upon the availability of the agent for affected areas when applied in a topical manner. That is, the formulation must not only incorporate sufficient active agent to properly treat but also the release of the active agent from the formulation is an absolute necessity.
In accordance with the present invention, a gel formulation has been developed which is suitable for treatment of both acne and psoriasis which incorporates vehicles for both solubilizing the active agent and for controlling release of the active agent from the gel to the skin condition.
SUMMARY OF THE INVENTION
In accordance with the present invention, a stable gel formulation for topical treatment of skin conditions in humans is used as an active agent having activity for treatment of acne and psoriasis and is insoluble in water. In combination therewith is a plurality of nonaqueous vehicles for both solubilizing the active agent and forming a gel therewith. The nonaqueous vehicles enable topical application of the gel to a skin condition with the vehicles each being present in amounts, in combination, to control the release of the active agent from the gel to the skin condition.
Other combinations of the vehicles provide a means to maximize the solubility of the active agent in the gel.
More particularly, the formulation comprises three vehicles and the active agents comprises a synthetic retinoid, preferably Ethyl-6-[2-(4,4-dimethylthiochroman-6-yl]nicotinate or any of the other synthetic retinoids disclosed in U.S. Pat. Nos. 4,739,098; 4,923,884; 4,810,804; 5,013,744; 4,895,868; 5,006,550; 4,992,468; 5,149,705; 5,202,471; 5,130,335; and 5,134,159, these patents being incorporated into the present application by this specific reference thereto.
Vehicles are used to both solubilize the active agent and form a gel and preferably comprise Polysorbate 40 (a polyhydroxy organic compound), Poloxamer 407 and Hexylene glycol.
More specifically, the present invention provides a stable gel formulation having an effective amount of a compound having the formula: Ethyl-6-[2-(4,4-dimethylthiochroman-6-yl]nicotinate, (sometimes hereinafter referered to as AGN) for treating acne in a pharmaceutical carrier comprising water, edetate disodium, ascorbic acid, Carbomer 934P, Poloxamer 407, polyethylene glycol, Polysorbate 40, hexylene glycol, butylated hydroxytoluene, butylated hydroxyanisole, benzyl alcohol, and tromethamine.
A method in accordance with the present invention for preparing a formulation for topical treatment of both acne and psoriasis includes the steps of mixing purified water, edetate disodium, ascorbic acid and Carbomer 934P (a polyacrylic acid) until the carbomer is dispersed to form a part I, mixing purified water, Poloxamer 407 to form a part II and adding part II to part I while homogenizing same.
The method further includes mixing polyethylene glycol, Polysorbate 40, hexylene glycol, butylated hydroxytoluene and butylated hydroxyanisole and heating to dissolve same. Thereafter, the heated mixture is cooled to room temperature and benzyl alcohol and Ethyl-6-[2-(4,4-dimethylthiochroman-6-yl]nicotinate are added thereto to form a part III.
Purified water is mixed with tromethamine to form part IV and part III is added to parts I and II while stirring before part IV with mixing until homogeneous.
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patent: 90/14833 (1990-12-01), None
patent: 98/56375 (1998-12-01), None
Sefton et al., “AGN 190618, An Investigational Retinoid Gel . . . ” The Journal of Investigative Dermatology, vol. 101(3), p. 470, #496, Sep. 1993.*
Weinstein et al., “New Topical Retinoid for Therapy of Psoriasis . . . ” The Journal of Investigative Dermatology, vol. 100(4), #332, 1993.*
Shalita et al., “Double-Blind Study of AGN 190618 . . . ” The Journal of Investigative Dermatology, vol. 100(4), p. 542, #325, Apr. 1993.*
Remigton's Pharmaceutical Sciences, 8thEd., Philadelphia College of Pharmacy and Science, pp. 350,821,822,825,1286,1305,1313,1314, 1990.
Allergan Sales Inc.
Hackler Walter A.
Pak John
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