montelukast

(mon-teh-LOO-kast) The active ingredient in a drug used to treat symptoms of asthma, such as trouble breathing, tight chest, wheezing, coughing, and runny nose. Montelukast blocks the action of a substance that causes airways in the lungs to narrow and causes other symptoms of asthma. It is a type of leukotriene receptor antagonist and a type of antiasthmatic agent.