A Mechanistic Study to Evaluate the Efficacy of Montelukast on Airway Function in Asthma

Rationale: It has been proposed that there is a specific LTE4-receptor which causes infiltration of inflammatory cells and bronchoconstriction. This receptor is not blocked by the current class of clinically used antileukotriene drugs. The proposal receives circumstantial support from animal models, but has not been tested in a controlled study in subjects with asthma. Study design: The study will have a placebo-controlled, double-blind, randomised, cross-over design. A screening period will precede the randomized phase. This will include routine haematology, blood chemistry and urinalyses, baseline measurements of exhaled nitric oxide, airway responsiveness to inhaled methacholine and, on a separate day, airway responsiveness to inhaled LTE4. Provided the subjects fulfill inclusion but not exclusion criteria, subjects will be randomized to receive medication with montelukast or matching placebo for 5 to 7 days. The intervention will be evaluated in the inhalation challenge setting using a rising dose cumulative protocol for inhaled LTE4 to induce a standardised bronchoconstriction (25% drop in lung function). The LTE4 challenge test is performed on the last treatment day, with the last dose of study medication taken in the research laboratory. Sampling of urine, blood and induced sputum will be done for measurements of lipid mediators and cellular responses.