mechanisms of action

Last reviewed 01/2018

Molecular mechanisms - inhaled glucocorticoids are highly lipophilic. They rapidly enter airway cells and bind to cytosolic receptors. The glucocorticoid-receptor complex then moves into the nucleus and binds to the DNA where they alter gene transcription or modulate gene expression which results in altered protein synthesis (1). The complex may also inhibit the transcription of the genes for cytokines implicated in asthmatic inflammation.

Cellular effects - inhaled steroids may have inhibitory effects on many cells involved in airway inflammation including macrophages, T-lymphocytes, eosinophils, and airway epithelial cells. They may also inhibit plasma exudation and mucus secretion in inflamed airways.

Anti-inflammatory effects - there is a marked anti-inflammatory effect of inhaled glucocorticoids on the bronchial mucosa in patients with asthma.

Effects on airway hyperresponsiveness - inhaled steroids consistently lessen airway hyperresponsiveness in children and adults with asthma.

Reference:

• (1) Anthracopoulos MB, Priftis KN, Russell G. Safety of inhaled corticosteroids. Why the variation in systemic adverse effects? Current Pediatric Reviews 2008;4:198-215