Study objective: Evidence for the anti-inflammatory activity of leukotriene receptor antagonists in humans is somewhat limited. There are also no data comparing the anti-inflammatory effects of leukotriene receptor antagonists with those of inhaled corticosteroids. This study was designed to assess the clinical efficacy and anti-inflammatory effects of leukotriene receptor antagonist plus low-dose inhaled corticosteroids compared to those of a high-dose inhaled corticosteroid in patients with mild-to-moderate asthma.
Methods: Forty-nine patients with newly diagnosed asthma were recruited. They were randomly assigned to groups that received, for a 6-week period, either (1) budesonide, 600 μg bid (1,200 μg/d) or (2) budesonide, 200 μg (400 μg/d), and zafirlukast, 20 mg bid. The variables of asthma control were recorded daily. Sputum induction and methacholine provocation tests were performed.
Results: The results indicated that the administration of a low-dose inhaled corticosteroid plus zafirlukast was as effective as that of a high-dose inhaled corticosteroid regarding clinical improvement and anti-inflammatory effects (ie, eosinophil percentage, and eosinophilic cationic protein [ECP] and cysteinyl leukotriene C4 levels in induced sputum). Nineteen (group 1, 8 patients; group 2, 11 patients) of 49 patients (38.8%) had returned to normal airway responsiveness after treatment. Among these patients, 16 patients (84.2%) had normal ECP levels and 10 patients (52.6%) had normal percentages of eosinophils. ECP level, but not the eosinophil percentage, was significantly associated with symptom scores. The peak expiratory flow rate (PEFR) showed a significant correlation with the provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) instead of with symptom scores.
Conclusions: The addition of a leukotriene modifier to treatment with low-dose inhaled corticosteroids is equivalent to treatment with high-dose inhaled corticosteroids in patients with newly diagnosed mild-to-moderate asthma. In addition to symptoms and PEFR, the monitoring of ECP and PC20 may be of great value in achieving optimal control of asthma.