A leukotriene antagonist (sometimes referred to as a leukast) is a drug that inhibits leukotrienes, which are fatty compounds produced by the immune system that cause inflammation in asthma and bronchitis, and constrict airways. Leukotriene inhibitors (or modifiers), such as montelukast (trade names Singulair and Montelo-10), zafirlukast, pranluka...