Asthma drug action cascade. Left: omalizumab and chromones block at the IgE/mast cell level. Centre: β2-agonists, theophylline, and muscarinic antagonists reverse the early bronchoconstriction response. Right: corticosteroids, antileukotrienes, and anti-IL-5/IL-4 biologics suppress the late inflammatory response and airway hyperresponsiveness.