The CysLTs, LTC4 and LTD4, are potent mediators of asthma and hypersensitivity. They induce bronchoconstriction, increase microvascular permeability, and are vasoconstrictors of coronary arteries. Their biological effects are transduced by a pair of GPCRs, CysLT1 and CysLT2. Zafirlukast is a…