Principles of Topical Dermatologic Therapy

Inert powders may be mixed with active agents (eg, antifungals) to deliver therapy. They are prescribed for lesions in moist or intertriginous areas.

Liquid vehicles include

• Baths and soaks

• Foams

• Solutions

• Lotions

• Gels

Baths and soaks are used when therapy must be applied to large areas, such as with extensive contact dermatitis or atopic dermatitis.

Foams are alcohol- or emollient-based aerosolized preparations. They tend to be rapidly absorbed and may be favored in hair-bearing areas of the body.

Solutions

Lotions are water-based emulsions. They are easily applied to hairy skin. Lotions cool and dry acute inflammatory and exudative lesions, such as contact dermatitis, tinea pedis, and tinea cruris.

Gels are ingredients suspended in a solvent thickened with polymers. Gels are often more effective for controlled release of topical agents. They are often used in acne, rosacea, and psoriasis of the scalp.

Combinations include

• Creams

• Ointments

Creams are semi-solid emulsions of oil and water. They are used for moisturizing and cooling and when exudation is present. They vanish when rubbed into skin.

Ointments are oil based (eg, petrolatum) with little if any water. Ointments are optimal lubricants and increase drug penetration because of their occlusive nature; a given concentration of drug is typically more potent in an ointment. They are preferred for lichenified lesions and lesions with thick crusts or heaped-up scales, including psoriasis and lichen simplex chronicus. Ointments are less irritating than creams for erosions or ulcers. They are usually best applied after bathing or dampening the skin with water.

The most common nonocclusive dressings are gauze dressings. They maximally allow air to reach the wound, which is at times preferred in healing, and allow the lesion to dry.

Wet-to-dry dressings are nonocclusive dressings wetted with solution, usually saline, that are used to help cleanse and debride thickened or crusted lesions. The dressings are applied wet and removed after the solution has evaporated (ie, wet-to-dry), with materials from the skin adhering to the dried dressing.

stasis dermatitis and ulcers

Occlusive dressings applied over topical corticosteroids to increase absorption are sometimes used to treat psoriasis, atopic dermatitis, skin lesions resulting from systemic lupus erythematosus, and chronic hand dermatitis, among other conditions. Systemic absorption of topical corticosteroids may occur and cause adrenal suppression. Local adverse effects of topical corticosteroids include development of skin atrophy, striae, miliaria, bacterial or fungal infections, and acneiform eruptions.

Other occlusive dressings are used to protect and help heal open wounds, such as burns; special silicone dressings are sometimes used for keloids.

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. Removal of hardened tar and dried paint from the skin may require a petrolatum-based ointment or commercial waterless cleanser.

keratinolytics, eg, for ichthyosis. They are most effective when applied to already moistened skin (ie, after a bath or shower). Cold creams are over-the-counter (OTC) moisturizing emulsions of fats (eg, beeswax) and water.

Excessive moisture in intertriginous areas (eg, between the toes; in the intergluteal cleft, axillae, groin, and inframammary areas) can cause irritation and maceration.

talc is more effective, talc may 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).

hyperhidrosis).

Topical anti-inflammatory agents are either corticosteroids or noncorticosteroids.

Corticosteroids are 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 when some drying is needed between the toes to treat tinea pedis. 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 agents1).

Topical antimicrobial agents include

• Antibiotics

• Antifungals

• Insecticides

• Nonspecific antiseptic agents

Antibioticsacne vulgariserythromycin are used for rosaceaStaphylococcus aureus and streptococci) coverage and can be used to treat impetigo when deep tissues are not affected (223) are other topical antibiotics used to treat impetigo.

Antifungals are used to treat candidiasis, a wide variety of dermatophytoses, and other fungal infections (see table Options for Treatment of Superficial Fungal Infections*).

InsecticidesInitial Treatment Options for Lice and Treatment Options for Scabies).

Nonspecific antiseptic agents include iodine solutions (eg, povidone iodine, clioquinol), gentian violet

psoriasis, seborrheic dermatitis, acne, and warts. Adverse effects are burning and, if large areas are covered, systemic toxicity. It should rarely be used in children and infants.

plantar keratodermas and ichthyosis. Adverse effects are irritation and intractable burning. It should not be applied to large surface areas.

atopic dermatitis, lichen simplex chronicus, and nummular dermatitis.

1. 1. Ruxolitinib (Opzelura) for atopic dermatitis. Med Lett Drugs Ther 64(1642):12-13, 2022.

2. 2. Stevens DL, Bisno AL, Chambers HF, et al: Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of America. Clin Infect Dis 59(2):147-159, 2014. doi: 10.1093/cid/ciu296

3. 3. Rosen T, Albareda N, Rosenberg N, et al: Efficacy and Safety of Ozenoxacin Cream for Treatment of Adult and Pediatric Patients With Impetigo: A Randomized Clinical Trial. JAMA Dermatol 154(7):806-813, 2018. doi: 10.1001/jamadermatol.2018.1103