Objectives The objective of this study was to investigate the efficacy in children of nebulised furosemide administered singly or in combination with β-cyclodextrins (β-CDs) on asthma exacerbations.

Methods A single-blinded randomised controlled study was conducted in five groups of children with moderate asthma. Twenty children were enrolled in each group: group 1 received nebulised salbutamol, group 2 received nebulised furosemide, group 3 received both salbutamol and furosemide, group 4 received a mixture of furosemide and β-CD in a 1:0.5 molar ratio, and group 5 received a mixture of furosemide and β-CD in a 1:1 molar ratio. Pulmonary function parameters, peak flow rates, respiratory rate, oxygen saturation and clinical scores were obtained before and after treatment.

Results The primary outcome of forced expiratory volume in 1 s (FEV_l) improved after drug administration in all five groups of patients. The greatest FEV_l% improvement was seen in group 3 children treated with the combination of furosemide and salbutamol (22.0±1.9; p<0.001). The greatest increases in forced vital capacity (FVC) were seen in group 3 (21.6±1.6; p<0.001) and group 4 (20.9±1.8; p<0.001).

Conclusions Complexes of furosemide and CDs led to a significant increase in peak flow rate and significantly improved FEV₁, FVC, respiratory rate, arterial oxygen saturation (SaO₂) and clinical scores as compared to other treatments. The complex effect was nearly equal to that of the furosemide and salbutamol combination. These results suggest that CDs are a promising approach for improving the efficacy of poorly water-soluble drugs administered by inhalation.