Table 1.

Clinical effects of montelukast in preschool children

Phenotype		Clinical effects of montelukast
Wheeze
	Episodic viral wheeze	Decrease in wheezing frequency after RSV infection. No short-acting effects on reducing wheezing episodes requiring rescue medicine, ER visit, and hospital admission
		Recommended as a therapeutic trial
	Multiple-trigger wheeze	Montelukast responder’ phenotype exists. Studying how to easily identify these phenotypes
		Recommended as an alternative treatment of low-dose ICS
Asthma
	Intermittent	Effective on reducing asthma exacerbation
		Recommended as an additional treatment of short-acting beta agonist
	Persistent	Effective on reducing serum EDN concentrations.
		Less effective than daily ICS for improving asthma symptoms and preventing exacerbation
		Recommended as an alternative treatment of low-dose ICS

RSV. respiratory syncytial virus; ER, emergency room; ICS, inhalation corticosteroids; EDN, eosinophil-derived neurotoxin.