Description: Montelukast is a selective leukotriene receptor antagonist that inhibits the effects of cysteinyl leukotrienes in the airways. Cysteinyl leukotrienes and leukotriene receptor occupation have been correlated w/the pathophysiology of asthma, including airway oedema, smooth muscle contraction, and altered cellular activity associated w/the inflammatory process, which contribute to the signs and symptoms of asthma.