Table 1.

Mechanism of actions of inhaled corticosteroids in asthma

	Genomic	Non-genomic
Action mediated through	Cytoplasmic glucocorticoid receptor-α [9].	Membrane-bound or cytoplasmic glucocorticoid receptor or direct interaction with airway vasculature [11].
Onset of action	Hours to days [11].	Seconds to minutes [11].
Effects	- Selective switch off in multiple activated inflammatory genes (transrepression) by reversal of histone acetylation [9, 15, 16]. - Increasing mRNA degradation and hence blocking production of pro-inflammatory cytokines [11]. - Increasing the synthesis of anti-inflammatory proteins [9].	- Suppressing the increased microvascular permeability and plasma leakage into the airway lumen [29–32]. - Acutely suppressing airway hyperperfusion in a dose-dependent manner [27]. - Inhibiting the remodeling process (only long-term therapy in a dose-dependent manner) [33, 34].