Inspiratory Profiles Through Easyhaler Dry Powder Inhaler During Acute Bronchoconstriction

Background: Dry powder inhalers (DPIs) are passive devices, which rely on a patient's inspiratory effort for drug dispersion and delivery. The aim of this study was to assess how acute bronchoconstriction affects the ability to use Easyhaler DPI in adults. Methods: This study was conducted as part of a parallel-group clinical trial assessing use of Salbutamol Easyhaler, Budesonide-formoterol Easyhaler and salbutamol pMDI with spacer during a methacholine challenge (MC) test. The inhalations through both Easyhaler variants, the inhaler for the single active substance product (EH-mono) and the inhaler for the combination product (EH-combi), were recorded at baseline and during bronchoconstriction. Peak inspiratory flow (PIF), flow rate acceleration and inhalation volume after PIF were compared to the criteria for successful inhalation. Results: The study population consisted of 120 adult subjects indicated for MC as a diagnostic test for asthma, with 60 subjects in both Easyhaler arms. With EH-combi 98.3% and 91.4% passed the criteria (PIF ≥30 L/min, inhalation acceleration ≥0.7 L/s², and inhalation volume ≥500 mL after PIF) for successful inhalation at baseline and during bronchoconstriction, respectively. With EH-mono, success rates were 95.0% and 88.1% at baseline and during bronchoconstriction, respectively. The most common reason for not passing the criteria was slow inhalation acceleration. Aside from two subjects using EH-mono during bronchoconstriction, all subjects were able to generate PIF ≥ 30 L/min. Conclusions: During an acute obstructive event, the vast majority of patients have no difficulty in achieving sufficient PIF, inhalation acceleration, and volume after PIF when using an Easyhaler DPI.