Synergistic effect of formoterol and mometasone in a mouse model of allergic lung inflammation

Background and purpose: Controversy still exists as to whether or not inhaled β2‐adrenoceptor agonists and corticosteroids act synergistically in vivo. In this study, we have used a murine model of lung inflammation to study the synergistic effect of an inhaled β2‐adrenoceptor agonists (formoterol) and an inhaled corticosteroid (mometasone). Experimental approach: Actively sensitized mice were challenged with aerosolized ovalbumin, once a day, for three consecutive days. Three days after the last of the three challenges, a final allergen challenge was given. Allergen‐induced increase in Penh was measured 4 h after the last challenge. A day after the last challenge, increased airway sensitivity to aerosolized methacholine was demonstrated and this was concomitant with an influx of inflammatory cells in the bronchoalveolar lavage fluids. Key results: Mometasone (0.1 to 3 mg kg−1) given intranasally either an hour before or after the last allergen challenge, dose‐dependently inhibited all parameters. When given intranasally either one or three hours after the last allergen challenge, but not an hour before, formoterol (1.5 to 150 μg kg−1) also dose‐dependently inhibited most of the parameters to different degree. A synergistic effect on the allergen‐induced increase in Penh was demonstrated for mometasone and formoterol given in combination, an hour after the challenge, at the following doses: mometasone/formoterol (in μg kg−1) 1/10, 1/100, 5/10, and 5/100. Conclusions and implications: Our results support the hypothesis that when given as a fixed combination, inhaled corticosteroid and β2‐adrenoceptor agonist act synergistically in vivo. British Journal of Pharmacology (2007) 152, 83–90; doi:10.1038/sj.bjp.0707381