Method and Compositions for Treating Acne

The present invention pertains to a method of treating acne and to compositions useful in the practice of that method.

While presently not curable, acne can be successfully treated in many cases. Therapies currently in use or suggested, include the application of compositions containing such agents as benzoyl peroxide, sulfur, retinoic acid (including derivatives thereof) and salicylic acid. Many of these produce redness, peeling and desquamation of the treated skin and in addition, there is some evidence that benzoyl peroxide may have antibacterial action against Propionibacterium acnes (P.acnes), one of the two principal microorganisms associated with the condition.

The present invention is based on the discovery that the application of a topical vasodilator to the locus of a conglobate or dystic acne papule can effect a rapid improvement in the lesion. Vasodilators generally include smooth muscle relaxants such as nitrate esters of polyols (or derivatives of polyols) nitrites and the like. Such agents are often used in the treatment of the pain of angina pectoris and other spasms and include such compounds as amyl nitrite, glyceryl trinitrate, erythrityl tetranitrate, isosorbide dinitrate, mannitol hexanitrate, pentaerythritol tetranitrate, propatylnitrate, triethanolamine trinitrate, clonitrate and the like. Generally such agents have been administered for this purpose by the oral, sublingual or inhalation routes although systemic action upon transdermal administration utilizing polymeric diffusion matrices or biphasic lipophilic/hydrophilic carriers has been reported; see e.g., U.S. Pat. Nos. 4,291,015 and 4,322,433. The present method in contrast envisions and requires only local application and action at the loci of acne papules.

Without wishing to be bound by any theory of action, it appears the effectiveness of vasodilating nitrates and nitrites involves assisting the body's own defense against infection. P. acnes is a facultative anaerobic bacterium commonly found in acne papules and the presence of an anaerobic infection in otherwise healthy patients may be traceable to a temporary inadequacy in vascular supply in the rapidly enlarging pilosebaceous organ in which the acne process occurs. This impairment of vascular circulation not only may produce inadequate oxidation, permitting facultative anaerobes to thrive, but also reduce the effectiveness of P. acnes antibodies, titers of which generally parallel the clinical severity of the acne.

Whatever the mechanism of action, the effectiveness of the treatment can be readily observed in the clinic. In one study, twenty-five subjects suffering from severe acne presenting large (over 5 mm diameter) and tender papules applied to the loci of papules compositions containing 0.5 to 1% nitroglycerin in a homogeneous carrier comprising as its major components lanolin and petrolatum in a weight ratio of about 1:3. Application was made once a day, every morning. Such lesion when untreated generally persist in size and soreness for about three weeks. When so treated, the lesions decreased in size and tenderness in most cases after about 3 to 4 days.

Ordinarily the compositions can contain from about 0.5 to about 2% by weight of nitrate or nitrite, preferrably from about 0.5 to 1%. The remainder of the composition will comprise carriers suitable for ointment or gel formulations well known in this field; see e.g., U.S. Pat. No. 4,318,907. Since, however, systemic vasodilating activity is not desired in the present invention, formulation which enhance percutaneous bioavailability should be avoided, see e.g., U.S. Pat. No. 4,322,433. Suitable carriers include ointment bases such as lanolin, higher alkyl alcohols, petrolatum and similar lipophilic materials. A typical formulation is as follows:

The above ingredients are thoroughly blended producing a homogeneous ointment which is applied to the loci of acne papules one or more times a day.

The above and other compositions of the present invention should be applied sparingly to loci of acne papules. There is no advantage to applying such compositions to large unaffected areas. The amount applied need be only sufficient to effect local vasodilation at the site of the papule while at the same time being less than an amount which normally produces systemic effects.