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Is montelukast useful in the management of acute bronchiolitis?

Three Part Question

In a 4 month old boy with acute bronchiolitis [patient], is oral montelukast [intervention] more effective than placebo [comparison] at reducing length of stay [outcome]?

Clinical Scenario

It is mid-winter and a 4 month old boy has been admitted to the last bed in our acute admissions ward. He has typical signs and symptoms of moderate bronchiolitis and you wonder if there is a role for oral montelukast in his management.

Search Strategy

Secondary source
A search of Cochrane library using the search terms ‘montelukast AND bronchiolitis’ and 'leukotriene receptor antagonist AND bronchiolitis’
Primary source
A search of Medline from 1950-January week 4 2011 via OVID using the same search terms.

Search Outcome

The search of Cochrane Library revealed no relevant reviews.
The search of Medline revealed 28 papers, two of which were relevant.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Amirav et al
53 children aged one to 24 months hospitalised with bronchiolitis to receive 4mg montelukast v. placebo on each day of admission until discharge Double-blind, placebo-controlled randomised trial (Level 1b)Length of stay (LOS)-daysNo significant difference: mean LOS 4.65 days with montelukast v 4.63 days with placebo. Mean difference in LOS -0.02 days (95% CI: -1.05 to 1.08)
Zedan et al
85 children aged one to 24 months admitted with bronchiolitis to receive 4mg montelukast v. placebo on each day of admission until dischargeDouble-blind, placebo-controlled randomised trial (Level 1b) Length of stay (LOS) in hoursSignificant reduction in mean length of stay with montelukast: 3.34 days with montelukast v 5.42 days with placebo; P = 0.003; Mean difference in LOS -2.08 days (95% CI: -3.17 to -0.98)No details on patients RSV status


Bronchiolitis, usually associated with Respiratory Syncytial Virus (RSV), is the commonest respiratory infection in infants. Each year during winter it results in large numbers of hospital admissions, significant morbidity and sometimes death. While nebulised hypertonic saline may be effective in reducing length of hospital stay most treatments including bronchodilators and corticosteroids have not proven to be clinically useful. Supportive treatment includes maintaining oxygen saturations above 92% and ensuring adequate hydration. Any treatment which reduces length of stay in hospital due to bronchiolitis would be of great benefit. Montelukast is a leukotriene receptor antagonist which is commonly used as an add-on therapy in asthmatic patients. Increased levels of cysteinyl leukotrienes are found in infants with RSV infection. Montelukast competitively antagonises the cysteinyl leukotriene 1 receptor. It is postulated that this drug might reduce bronchial inflammation, mucosal oedema and broncho-constriction in infants with bronchiolitis. Both studies are very similar in design, inclusion/exclusion criteria, interventions and clinical outcomes. The first study failed to demonstrate any benefit associated with montelukast therapy. The second study demonstrated a significant reduction in length of stay (LOS) and a significant reduction in mean clinical severity scores at 24 hours (4.66 with montelukast v 6.08 with placebo; P = 0.01). While both studies state that they are adequately powered to detect a decreased LOS of 30% it is possible that either result has occurred by chance. When we combine the results the fixed effects weighted mean difference in LOS was significant for montelukast (-0.48 days; 95% CI: -0.83 to -0.14). As there are only two studies we do not report on heterogeneity. Although both studies included children up to two years, most participants were under 12 months, decreasing the risk that they were presenting with early asthma rather than bronchiolitis. As leukotriene levels appear to peak very early and resolve quickly in RSV infection it has been suggested that the opportunity for montelukast therapy may have been missed by the time children are admitted to hospital. Amirav et al reported ten adverse events (wheeze after administration, diarrhoea and rash) however none of these were determined to be drug related and there was no difference between groups. Kearns et al showed that montelukast given for a course of 7 days in 1-3 month old infants was generally well tolerated and could probably be prescribed safely in this younger age group.

Clinical Bottom Line

Given the inconsistent results between the studies there is currently insufficient evidence to recommend oral montelukast therapy in infants admitted with acute bronchiolitis. (Grade D) Montelukast may reduce length of hospital stay and clinical severity scores in these patients. (Grade D) Further research is required to evaluate this therapy, particularly in the early stages.


  1. Amirav I, Luder A, Kruger N, et al. A Double-Blind, Placebo-Controlled, Randomized Trial of Montelukast for acute bronchiolitis. Pediatrics 2008;122:1249-1255
  2. Zedan M, Gamil N, El-Assmy M, et al. Montelukast as an episodic modifier for acute viral bronchiolitis: a randomized trial. Allergy Asthma Proc 2010;31:147-53