Clinical Pharmacology of Corticosteroids.

Corticosteroids have numerous applications in treating inflammation and diseases of immune function based on their significant anti-inflammatory and immunosuppressive effects. Corticosteroids modulate immune function through various effects in the nucleus of numerous cells. When used in pharmacologic doses to suppress allergic responses or inflammation, these agents can cause numerous adverse effects associated with an excess of glucocorticoid activity. Prolonged use (>2 wk) results in suppression of the hypothalamic-pituitary-adrenal axis, which requires tapering of doses. Dosing strategies for systemic corticosteroids are designed to minimize the risk for hypothalamic-pituitary-adrenal axis suppression. Topical administration of corticosteroids, including oral inhalation, is often used to avoid the significant adverse effects associated with chronic use. Inhaled corticosteroids are potent synthetic agents that exert their actions locally in the airways but can cause systemic effects based on several factors that influence systemic bioavailability. Inhaled corticosteroids are the cornerstone of asthma therapy and important options for COPD in patients who experience frequent exacerbations. By the nasal route, they are the most effective therapy for treating moderate-to-severe allergic rhinitis.