In an 8-week study in paediatric patients 6 to 14 years of age, montelukast 5 mg once daily, compared with placebo, significantly improved respiratory function (FEV1 8.71% vs 4.16% change from baseline; AM PEFR 27.9 L/ min vs 17.8 L/ min change from baseline) and decreased "as-needed" β -agonist use (-11.7% vs +8.2% change from baseline).