Corticosteroids, Dermatologic

Definition

Dermatologic corticosteroids are anti-inflammatory compounds formulated for application to the skin. They are intended for local effects only and are not meant for internal use.

Purpose

Dermatologic corticosteroids are used to treat skin conditions that involve inflammation, usually marked by redness or itching. These include contact dermatitis, atopic dermatitis, nummular eczema, stasis eczema, asteatotic eczema, lichen planus, lichen simplex chronicus, insect and arthropod bite reactions, and first- and second-degree localized burns and sunburns.

In addition, dermatologic corticosteroids may be used together with other drugs to treat the symptoms of other conditions which are marked by inflammation of the skin.

Description

All dermatologic steroids are based on the natural hormone hydrocortisone, but most have been subject to chemical modification to increase their effectiveness. While many chemical changes to the original molecule will increase the anti-inflammatory effects, the best known is halogenation, replacing one or more of the carbon atoms in the molecule with an atom of fluorine or, less often, chlorine. This change increases the anti-inflammatory effects of the steroid but also increases the risk of some adverse effects.

Topical steroids are usually classed by their potency, ranging from very high to low potency. The most powerful steroids include clobetasol propionate, diflorasone diacetate, and halobetasol propionate. The high and medium potency group includes betamethasone valerate, desoximetasone, fluocininide, halcinonide, and fluandrenolide. Low potency topical steroids include desonide, dexamethasone, fluocinolone acetate, and hydrocortisone.

Topical steroids are particularly affected by their vehicle, which can alter the potency of the product and is particularly important in view of the parts of the body being treated. Lotions are liquid at room temperature and are usually the best choice for application to hairy areas of the body since they can easily reach past the hair. Creams are semi-solid and appropriate for application to most areas. They are usually designed to disappear and leave no sticky residue. This feature makes them appropriate for areas such as the palms of the hands, the face, or areas that are in direct contact with clothing. Ointments are thicker than creams and tend to stay on the skin longer than creams. Pastes are particularly thick ointments, often containing a powder such as zinc oxide, and may be used where a protective effect is needed.

Because of variations in skin thickness, it is essential to match the potency of the steroid with the area being treated. Areas of thick skin may require a very potent steroid in order to penetrate the outer layer of skin. In areas where the skin is thin, a high potency steroid may increase the risk of serious adverse reactions.

Recommended dosage

Most topical steroids are applied twice a day, but applications as frequently as four times a day may be appropriate. In some cases, penetration through the skin may be increased by use of occlusion.

Precautions

Excessive use of topical corticosteroids may lead to systemic side effects. Patients using high potency steroids over large areas of the body for a prolonged period should have adrenal function tests.

Normally, areas covered by steroid creams should not be bandaged, since doing so increases the absorption of the steroid and may lead to increased adverse effects.

Some commercially available formulations of topical corticosteroids contain sulfites that may cause allergic reactions. Allergic reactions to other ingredients in topical formulations are very infrequent but have been reported.

Topical corticosteroids should not be used in patients with markedly impaired circulation since skin ulceration has occurred in these patients following use of the drugs.

Topical corticosteroids should be used with extreme caution in areas where the skin is infected and should never be used in infected areas unless the infection is being appropriately treated.

When used properly, these medicines have not been shown to cause problems in humans. As of 2005, studies on birth defects have not been done in humans. However, studies in animals have shown that topical corticosteroids, when applied to the skin in large amounts or used for a long time, can cause birth defects. Maternal use of topical corticosteroids has not been reported to cause problems in nursing babies when used properly. However, corticosteroids should not be applied to the breasts before nursing.

Side effects

When dermatologic corticosteroids are used properly, adverse effects are very rare. Even so, the following effects have been reported:

• blood-containing blisters on skin
• burning and itching of skin
• increased skin sensitivity (for some brands of betamethasone lotion)
• lack of healing of skin condition
• numbness in fingers
• painful, red, or itchy, pus-containing blisters in hair follicles
• raised, dark red, wart-like spots on skin, especially when used on the face
• skin infection
• thinning of skin with easy bruising

Excessive use, either because of use of an inappropriately potent steroid, prolonged use, or inappropriate use of occlusion has been known to lead to more severe adverse effects. However, these reactions are very rare.

Interactions

When used properly, topical steroids have no drug interactions or interactions with foods because they do not reach significant levels in the body. Application of another ointment to the same area at the same time may dilute the corticosteroid ointment and result in lowered effectiveness.

Resources

BOOKS

Beers, Mark H., ed. Merck Manual of Medical Information: Home Edition. Riverside, NJ: Simon & Schuster, 2004.

Green, Steven M. Tarascon Pocket Pharmacopoeia. Delux Labcoat Pocket Edition. Lompoc, CA: Tarascon Publishing, 2005.

Physicians' Desk Reference 2005. Montvale, NJ: Thomson Healthcare, 2004.

White, Gary M., and Neil H. Cox. Diseases of the Skin: A Color Atlas and Text. Orlando, FL: Mosby, 2002.

KEY TERMS

Corticosteroids— Any of the steroid hormones produced by the adrenal cortex or their synthetic equivalents.

Dermatitis— A disease in which the skin is red and painful. This condition may have different causes. In contact dermatitis, the redness is a reaction to something touching the skin, such as a fabric dye or a metal. Atopic dermatitis is an intense reddening reaction, associated with allergies.

Eczema— A skin disease that causes redness, itching, and scaly or crusty sores. In asteatotic eczema the skin is dry and scaly. Stasis eczema is caused by reduced blood flow.

Lichen planus— An uncommon disorder involving a recurrent, itchy, inflammatory rash or lesion on the skin or in the mouth. The exact cause is unknown, but the disorder is likely to be related to an allergic or immune reaction. The skin lesions are distinct from other disorders.

Systemic— Affecting the entire body.

Topical— Pertaining to a particular surface area and affecting only the area to which it is applied.

Ulceration— Being eroded away, as by an ulcer.