Topical Corticosteroids

Corticosteroids are a commonly prescribed class of medications used to treat a wide variety of inflammations occurring within the body. The most prescribed corticosteroids are those used to treat asthma, the inflammation of the airways and lungs. In a topical formulation, corticosteroids are used to treat and to resolve inflammations and related skin conditions.

Corticosteroid substances include both natural and synthetically produced hormones, the chemicals employed within the body through production in the glands that form the endocrine system. Hormones are primarily messengers, whose glandular secretion and directions throughout the body are controlled in the hypothalamus, a region of the brain responsible for many of the body's involuntary regulatory actions. Natural corticosteroids are an end product of a system described as the hypothalamus/anterior pituitary/andrenocortical axis (the HPA axis); these hormones are manufactured within the adrenal glands, each located above a kidney. Corticosteroids in general have a similar chemical composition to that of the male sex hormone, testosterone.

Corticosteroids are also known as glucocorticoids, as they impact the utilization and metabolism of the fats ingested into the body through diet. Cortisol, the natural hormone that gives it name to the group, is referred to as the stress hormone. When the synthetic form of the hormone, cortisone, is injected into the body, it is converted into cortisol for effective anti-inflammatory use.

Steroids are naturally occurring, fat-soluble substances, chemically defined by the 17 carbon atoms that form four carbon rings in the structure. The word steroid was invented in the 1920s to better describe the sterol group of proteins, of which cholesterol is the most prominent. In contrast to muscle-building anabolic steroids, whose notoriety through their performance-enhancing use by athletes has skewed much of the popular perception as to how a steroid functions, the steroids' designation is a part of a very broad classification, including substances as diverse in their function as vitamin D, testosterone, and the phytosteroids, the steroids present in plants and consumed in food products.

The skin is the body's largest and most exposed organ, comprising approximately 15% of body weight. The skin functions as a component of immune system, the frontline defense against the entry of a multitude of pathogens into the body. The skin is composed of two distinct parts: the epidermis, which is the thin, flexible outer layer, and the dermis, the thicker second layer, where the subcutaneous (below skin surface) glands, such as the sweat glands and sebaceous (oil) glands, and hair follicles are located. The epidermis does not have any direct supply of nutrients by way of the capillary network of the cardiovascular system; the epidermis receives its necessary nutrition through the diffusion of these substances from the dermis.

Inflammatory skin conditions tend to affect the epidermis only. The conditions commonly treated by way of a topical corticosteroid include eczema, a non-contagious skin disease that may persist for an indefinite period, which presents as an uncomfortable itching, a red rash, and, in some instances, lesions on the epidermal surface. Psoriasis is a similar skin condition in its effect on the skin to that of eczema. The precise cause of psoriasis is undetermined; psoriasis is evidenced by a red-colored inflammation with a rough, uneven surface, which in some cases starts with the appearance of silver-colored scales formed on the skin surface. Various forms of psoriasis affect the elbows, knees, groin, and the fingernail structure.

In addition to the discomfort caused to the skin through the presence of the infection, the rubbing and chafing of sports equipment, coupled with the effect of perspiration and drying of the skin make sports participation an often uncomfortable proposition for the athlete. As many inflammatory skin conditions are unsightly, a long-term visible infection can also present psychological problems.

Topical steroids are manufactured in a variety of formulations, including ointments, creams, gels, and lotions. The type of topical application will be determined by the nature of the skin where the inflammatory condition is present. The anti-inflammatory properties of the topical corticosteroids are not universal in strength; the potency of these medications is rated in seven separate categories, from those with ultra-high potency to the lowest potency. An example of a low potency topical corticosteroid is hydrocorti-sone, used to treat the sensitive skin of young children or the facial or groin areas of adults. The ultra-high potency formulation is often prescribed to counter inflammations such as chronic eczema lesions on the thicker skin of the elbow or palms of the hand.

Topical corticosteroids have a number of well-known side effects, each of which must be considered at the time of the prescription. It is for this reason that topical corticosteroids are not available as over-the-counter (OTC) medications, but by prescription only. These effects include two types of temporary skin damage, reversible skin atrophy (a loss of health in the epidermis), and striae, the formation or lines or marks on the surface of the skin. These medications may also cause a distension of the capillaries in the area of the application of the corticosteroid, the appearance of bruising, and temporary acne. In a naturally dark skinned person, the cortico-steroid may cause hypopigmentation, a temporary lightening of the natural color of the skin.