BACKGROUND Montelukast, a leukotriene receptor antagonist, improves parameters of asthma control including forced expiratory volume in one second (FEV₁) when given orally to patients aged six years or older. This study was undertaken to compare the effect on FEV₁ of intravenous and oral montelukast and placebo during the 24 hour period following administration.

RESULTS Compared with placebo, intravenous and oral montelukast significantly increased the AUC_{0–24 h} (means of 20.70%, 15.72%, and 7.75% for intravenous, oral and placebo, respectively; no statistical difference between intravenous and oral). The difference in least square means from placebo for intravenous montelukast was 13.27% (95% CI 7.07 to 19.46), p<0.001 and for oral montelukast was 7.44% (95% CI 1.20 to 13.68), p = 0.020. The maximum percentage change in FEV₁was not significantly different for intravenous and oral montelukast (difference in least square means 6.78% (95% CI –0.59 to 14.15), p = 0.071). The mean percentage change in FEV₁ for intravenous montelukast was greater than for oral montelukast within the first hour (15.02% vs 4.67% at 15 min, p⩽0.001; 18.43% vs 12.90% at one hour, p<0.001 for intravenous and oral montelukast, respectively (placebo 3.05% at 15 minutes, 7.33% at one hour). Intravenous and oral montelukast were similar to placebo in the frequency of adverse events.

CONCLUSIONS The onset of action for intravenous montelukast was faster than for oral montelukast and the improvement in airway function lasted over the 24 hour observation period for both treatments. Although not well understood, there was a trend toward a greater improvement in FEV₁ with intravenous than with oral montelukast. These findings suggest that leukotriene receptor antagonists should be investigated as a treatment for acute severe asthma.