Montelukast for Children With Asthma

To the Editor.—Montelukast (MK-0476) is an orally administered, specific cysteinyl leukotriene receptor antagonist now with labeling approved by the Food and Drug Administration for the treatment of asthma. The study by Dr Knorr and colleagues¹ reported that montelukast improved morning forced expiratory volume in 1 second in 6- to 14-year-old children with chronic asthma. The most common adverse experiences were headache, asthma, and upper respiratory tract infection. However, the authors also reported an increase in fever (7.5% with montelukast vs 3.7% with placebo) and influenza (8.5% with montelukast vs 4.4% with placebo) and a decrease in abdominal pain (5% with montelukast vs 10.4% with placebo).

These observations raise 2 possibilities of potential clinical concern. First, the anti-inflammatory effect of montelukast might delay killing of virus by the immune system. Second, the anti-inflammatory effect of montelukast might mask the pain associated with abdominal infections.

The leukotriene receptors have not been sequenced except for the noncysteinyl leukotriene B₄ (LTB₄) receptor. The proinflammatory fMet-Leu-Phe (MLF) receptor is the closest homolog found on Basic Local Alignment Search Tool (BLAST) searching (of the approximately 400 sequenced G-linked protein receptors) to this LTB₄ receptor.² The potential ligand for the cysteinyl leukotriene C₄ receptor would be leukotriene C₄, which has some similarity to the methionyl MLF ligand for the MLF receptor.²

The anti-inflammatory leukotriene receptor antagonists are becoming important in the treatment of asthma. Further definition of the extent to which their anti-inflammatory effect influences the course of infections and the production of pain by pathologic processes is needed.