Abstract: AIM: To describe the relationship of medication use with small airway function and airway inflammation in patients with totally controlled asthma. METHODS: Maximum expiratory flow rate at 25% and 50% of forced vital capacity (V_max25% and V_max50%), and the percentage of eosinophil and the concentration of eosinophil cationic protein (ECP) in induced sputum in patients with totally controlled asthma who were using oral antiinflammatory agent without or with inhaled therapy and only inhaled therapy were measured. RESULTS: V_max25% and V_max50% of predicted normal value in 43 patients with clinically controlled asthma who were using oral antiinflammatory agent without or with inhaled therapy were significantly higher than those in 49 patients who were only using inhaled therapy [(67.1±11.9)% vs (54.4±12.6)% and (72.2±13.2)% vs (65.5±11.3)%, respectively] (all P＜0.05). It was found that percentage of eosinophil and level of ECP in patients with clinically controlled asthma who were using oral antiinflammatory agent without or with inhaled therapy were significantly lower than those in patients who were only using inhaled therapy [(3.8±2.9)% vs (5.1±2.0)% and (93.0±76.6) μg/L vs (130.4±86.7) μg/L, respectively] (all P＜0.01). CONCLUSION: The results of this study suggest that oral antiinflammatory agents with or without inhaled therapy may have a greater effect on small airway function and airway inflammation.

Key words: Asthma, Small airway function, Eosinophils, Eosinophil cationic protein