Ans. (b) Inhibits 5 -lipoxygenase* Leukotrienes are biochemical mediators that contribute to asthma symptoms# Contracting airway smooth muscle# Increasing vascular permeability and mucus secretion# Attracting and activating airway inflammatory cells* Zileuton is a 5-lipoxygenase inhibitor that decreases leukotriene production, and zafirlukast and montelukast are cysteinyl leukotriene receptor antagonists.* They are useful to prevent asthma attacks and cause modest improvements in lung function. They lessen the need for b2 - agonist rescue therapy.