While there are plenty of available treatment options, corticosteroids remain at the heart of eczema treatment. Corticosteroids refer to a class of steroid hormones naturally produced by the cortex of the adrenal glands. There are two kinds of corticosteroids: the glucocorticoids and the mineralocorticoids. The glucocorticoids are used in treating eczema due to their anti-inflammatory properties.
The adrenal glands are a pair of triangular organs perched on top of the kidneys. Each adrenal gland has two main parts: an outer cortex that produces corticosteroids and sex hormones, and an inner medulla that produces epinephrine. The synthesis of corticosteroids in the adrenal cortex begins when cholesterol is first converted to pregnenolone with the help of the enzyme desmolase. Pregnenolone eventually undergoes a series of steps to produce aldosterone (a mineralocorticoid), testosterone and cortisol (a glucocorticoid).
Glucocorticoids bind to receptors located within the cytoplasm of target cells. The glucocorticoid-receptor complex then translocates to the nucleus where they influence the expression of genes. Changes in gene expression are responsible for the physiological effects of glucocorticoids. In particular, the suppressive effect of glucocorticoids on the immune system is responsible for the drug’s beneficial effects on inflammatory conditions, such as eczema.
Glucocorticoids suppress an overactive immune system in eczema by increasing the expression of anti-inflammatory proteins and reducing the expression of pro-inflammatory proteins. Glucocorticoids also suppress the normal development and homeostasis of T lymphocytes, or vital white blood cells that are at the heart of all kinds of inflammation. Aside from immunosuppression, glucocorticoids also play important roles in other bodily processes.
Glucocorticoids are stress hormones that strive to maintain the concentration of glucose and other fuels in blood. In particular, glucocorticoids increase de novo production of glucose in the liver, mobilization of proteins and amino acids from tissues, and breakdown of triglycerides in fat.
In the developing fetus, glucocorticoids promote lung maturation and the production of surfactant in alveoli.
Routes of Administration
In the treatment of eczema, rashes and dermatitis, the topical form corticosteroids is the preferred route of administration, because the systemic side effects of corticosteroid use can be avoided. The topical corticosteroids differ in their strengths and potencies. Weaker steroids are preferred in areas covered with thin and sensitive skin, such as the face, diaper area, perianal skin and body folds. Medium-strength steroids are used for eczemas involving less sensitive areas such as the chest, back and extremities. Strong steroids are reserved for very severe eczemas and other conditions such as psoriasis, lichen planus, discoid lupus and neurodermatitis.
Aside from topical application, corticosteroids may also be inhaled, taken orally or administered intravenously. A particular disease process is matched by a physician to an appropriate route of administration.
Use in Eczema
Corticosteroids are classified according to their strengths. Understanding the strength of a corticosteroid is essential in determining the best type to use for specific eczemas and particular areas of the body affected. Examples of strong steroids include clobetasol, betamethasone and fluocinonide. Moderate steroids include triamcinolone, mometasone and fluocinolone. Hydrocortisone is an example of a weak steroid.