dermatologic disorders
Principles of Topical Dermatologic Therapy
Topical Agents
Major categories of topical agents include Cleansing Moisturizing Drying Anti-inflammatory Antimicrobial Keratolytic Astringent Antipruritic The principal cleansing agents are soaps, detergents, and solvents. Soap is the most popular cleanser, but synthetic detergents are also used. Baby shampoos are usually well tolerated around the eyes and for cleansing wounds and abrasions; they are useful for removing crusts and scales in psoriasis, eczema, and other forms of dermatitis. However, acutely irritated, weeping, or oozing lesions are most comfortably cleansed with water or isotonic saline. Water is the principal solvent for cleansing. Organic solvents (eg, acetone, petroleum products, propylene glycol) are very drying, can be irritating, and cause irritant or, less commonly, Allergic contact dermatitis (ACD) . Removal of hardened tar and dried paint from the skin may require a petrolatum-based ointment or commercial waterless cleanser. 2%, lactic acid 5 to 12%, and glycolic acid 10% (higher concentrations of glycolic acid are used as Keratolytics , eg, for Excessive moisture in intertriginous areas (eg, between the toes; in the intergluteal cleft, axillae, groin, and inframammary areas) can cause irritation and maceration. Powders dry macerated skin and reduce friction by absorbing moisture. However, some powders tend to clump and can be irritating if they become moist. Cornstarch andtalcare most often used. Althoughtalcis more effective,talcmay cause granulomas if inhaled and is no longer used in baby powders. Cornstarch may promote fungal growth. Super-absorbent powders (extremely absorbent powders) are occassionally required to dry very moist areas (eg, to treat intertrigo). solutions are another type of drying agent (often useful in Treatment ). Topical anti-inflammatory agents are either corticosteroids or noncorticosteroids. Corticosteroidsare the mainstay of treatment for most noninfectious inflammatory dermatoses. Lotions are useful on intertriginous areas and the face. Gels are useful on the scalp and in management of contact dermatitis. Creams are useful on the face and in intertriginous areas and for management of inflammatory dermatoses. Ointments are useful for dry scaly areas and when increased potency is required. Corticosteroid-impregnated tape is useful to protect an area from excoriation. It also increases corticosteroid absorption and therefore potency. Topical corticosteroids range in potency from mild (class VII) to superpotent (class I— see Table: Relative Potency of Selected Topical Corticosteroids ). Intrinsic differences in potency are attributable to fluorination or chlorination (halogenation) of the compound. Topical corticosteroids are generally applied 2 to 3 times a day, but high-potency formulations may require application only once a day or even less frequently. Most dermatoses are treated with mid-potency to high-potency formulations; mild formulations are better for mild inflammation and for use on the face or intertriginous areas, where systemic absorption and local adverse effects are more likely. All agents can cause local skin atrophy, striae, and acneiform eruptions when used for>1 month. This effect is particularly problematic on the thinner skin of the face, axillae, or genitals. Corticosteroids also promote fungal growth. Contact dermatitis in reaction to preservatives and additives is also common with prolonged use. Contact dermatitis to the corticosteroid itself may also occur. Perioral dermatitis occurs with mid-potency or high-potency formulations used on the face but is uncommon with mild formulations. High-potency formulations may cause adrenal suppression when used in children, over extensive skin surfaces, under occlusive dressings, or for long periods. Relative contraindications include conditions in which infection plays an underlying role and acneiform disorders. Noncorticosteroid anti-inflammatory agentsinclude tar preparations. Tar comes in the form of crudecoal tarand is indicated for psoriasis. Adverse effects include irritation, folliculitis, staining of clothes and furniture, and photosensitization. Contraindications include infected skin. Several herbal products are commonly used in commercial products, but their effectiveness has not been well established. Among the most popular are chamomile and calendula. For atopic dermatitis, the topical calcineurin inhibitorspimecrolimusandtacrolimusand the topical phosphodiesterase-4 inhibitorcrisaborolemay be used. Topical antimicrobial agents include Antibiotics Antifungals Insecticides Nonspecific antiseptic agents are used as primary or adjunctive treatment for Mild acne in patients who do not warrant or tolerate oral antibiotics. Topical Over-the-counter topical antibiotics such asbacitracinand polymyxin have been replaced by topical petrolatum for postoperative care of a skin biopsy site and to prevent infection in scrapes, minor burns, and excoriations. Topical petrolatum is as effective as these topical antibiotics and does not cause contact dermatitis, which these antibiotics, especially topicalneomycin, can cause. Also, the use of topical antibiotics and washing with antiseptic soaps in healing wounds may actually slow healing. are used to treat Treatment , a wide variety of ) are used to treat Lice Nonspecific antiseptic agentsinclude iodine solutions (eg, povidone iodine, clioquinol),gentian violet, silver preparations (eg,silver nitrate,silver sulfadiazine), and zinc pyrithione. Iodine is indicated for presurgical skin preparation.Gentian violetis used when a chemically and physically stable antiseptic/antimicrobial agent is needed and must be very inexpensive. Silver preparations are effective in treating burns and ulcers and have strong antimicrobial properties; several wound dressings are impregnated with silver. Zinc pyrithione is an antifungal and a common ingredient in shampoos used to treat dandruff due to psoriasis or seborrheic dermatitis. Healing wounds should generally not be treated with topical antiseptics other than silver because they are irritating and tend to kill fragile granulation tissue.Sodium hypochloritehas been used as an antiseptic agent in washes and sprays in the last few years. is used to treat Treatment , Astringents are drying agents that precipitate protein and shrink and contract the skin. The most commonly used astringent isaluminum acetatesolution. Usually applied with dressings or as soaks, astringents are used to treat infectious eczema, exudative skin lesions, and weeping pressure ulcers.Witch hazelis a popular over-the-counter astringent. is a topical antihistamine that is effective in treating itching of Supportive care , 