Cysteinyl leukotriene receptor 1 (CYSLTR1) is a GPCR through which leukotriene D4 mediates bronchoconstriction. CYSLTR1 antagonists work by antagonising the effects of proinflammatory leukotrienes (such as LTC4, LTD4 and LTE4), resulting in decreased inflammation and decreased hyperresponsiveness of airways to immune challenges (Capra et al. 1998, Snyder & Fleisch 1989, Wendell et al. 2020). The CYSLTR1 antagonists listed here comprise approved (montelukast, pranlukast and zafirlukast) and investigational drugs used in asthma therapy.