Sodium cromoglycate and eformoterol attenuate sensitivity and reactivity to inhaled mannitol in subjects with bronchiectasis

Background and objective: Dry powder mannitol has the potential to be used to enhance clearance of mucus in subjects with bronchiectasis. A reduction in FEV1 has been recorded in some subjects with bronchiectasis after inhaling mannitol. The aim of this study was to investigate if pre-medicating with either sodium cromoglycate (SCG) or eformoterol could inhibit this reduction in FEV1. Methods: A double-blind, placebo-controlled, randomized cross-over study was conducted. Lung function and airway response to mannitol was assessed on a control day and then re-assessed after pre-medication with placebo, SCG and eformoterol in nine subjects. Sensitivity to mannitol, expressed as the dose required to induce a 15% fall in FEV1 (PD15), and reactivity to mannitol, expressed as the % fall in FEV1 per mg of mannitol (response'dose ratio, RDR), are reported. Results: Subjects had an FEV1 of 68 ± 14% predicted, FVC of 97 ± 15% predicted and FEV1/FVC of 71 ± 8%. They were mildly hypoxemic and the SpO2 was 95 ± 2%.They had a PD15 to mannitol of 235 mg (95% CI: 150'368 mg) and a RDR of 0.057% fall in FEV1 per mg (95% CI: 0.038'0.085). After pre-medication with SCG, PD15 increased (773 mg, P < 0.05) and RDR was reduced (0.013, P < 0.05). Pre-medication with eformoterol also resulted in an increased PD15 (1141 mg, P < 0.01) and a reduced RDR (0.009, P < 0.01). A small but significant decrease in SpO2 from baseline was noted after mannitol in the presence of SCG (P < 0.05). Conclusions: Pre-medication with either SCG or eformoterol protects patients with bronchiectasis from developing a significant reduction in FEV1 after inhaling mannitol.