The role of LTRAs in the management of persistent asthma.

Two leukotriene receptor antagonists (LTRAs)--montelukast and zafirlukast--are currently available in the United States. Montelukast is approved for the treatment of asthma in patients as young as 2 years old and zafirlukast, in patients 7 years of age or older. In more than 15 clinical trials of LTRA therapy for mild to moderate persistent asthma, both of these oral agents produced rapid improvement in pulmonary function and daytime asthma symptoms. They also decreased the frequency of nocturnal awakening and the need for rescue therapy with beta2-adrenergic agonists and oral corticosteroids. These effects were maintained throughout the treatment period; tolerance did not develop. When used concomitantly with an inhaled corticosteroid (ICS), each LTRA further improved asthma control, thus permitting the partial or complete tapering off of the ICS dose needed to maintain clinical control. Although rare, previously undiagnosed cases of Churg-Strauss syndrome have been unmasked when ICS use is decreased or discontinued. The improved adherence gained with an oral agent administered as infrequently as once daily maximizes the effectiveness of these newest antiasthma medications.