Introduction
Montelukast was approved by the Food and Drug Administration (FDA) on February 20, 1998 for the treatment of asthma in children and adults. It has gained widespread acceptance as an adjunct to inhaled corticosteroids and beta-adrenergic agonists in the treatment of asthma in children and adults. By 2010, worldwide sales of montelukast exceeded $5 billion with $3 billion of that in the United States. The availability of generic montelukast since 2012 and the extension of the approved indications to include treatment of allergic rhinitis and exercise-induced bronchoconstriction have added to the drug's continued growth.