Targeting the Small Airways with Inhaled Corticosteroid/Long-Acting Beta Agonist Dry Powder Inhalers: A Functional Respiratory Imaging Study

Background: Peripheral deposition of inhaled medication is important as small airway disease has a key role in asthma. In this study, we compared the lung deposition at different mean flow rates of three inhaled corticosteroid (ICS)/long-acting beta(2)-agonist (LABA) combinations delivered by dry powder inhaler (DPI), that is, Foster NEXThaler(®) (extrafine formulation of beclomethasone/formoterol), Relvar Ellipta(®) (fluticasone furoate/vilanterol trifenatate), and Symbicort Turbohaler(®) (budesonide/formoterol). Materials and Methods: In vitro drug delivery parameters were applied to lung computerized tomography (CT) scans of 20 asthma patients by functional respiratory imaging (FRI). Aerosol airway deposition patterns were calculated as percentage (standard deviation) intrathoracic versus extrathoracic deposition, percentage peripheral deposition, and central-to-peripheral (C/P) ratio at different inspiratory mean flow rates. Results: At 60 and 40 L/min, intrathoracic deposition of ICS/LABA was significantly higher with NEXThaler versus Ellipta. Peripheral deposition (60 L/min) with NEXThaler was higher than Ellipta for ICS (24.7% [3.5%] vs. 5.0% [2.0%]; p < 0.001) and LABA (25.3% [3.5%] vs. 13.0% [3.0%]; p < 0.001). C/P ratio with NEXThaler was lower (indicating higher peripheral deposition) than Ellipta (ICS: 0.63 vs. 1.63; LABA: 0.63 vs. 0.99). Inspiratory flow rate did not impact lung deposition with NEXThaler or Ellipta. In contrast, Turbohaler performance was negatively impacted by decreasing inspiratory flow rate. In fact, although lung deposition with Turbohaler was similar to that of NEXThaler at 60 L/min, lung deposition with Turbohaler was significantly lower than NEXThaler at both 40 L/min (∼30%) and 30 L/min (∼50%). Conclusions: Using FRI, we demonstrated better peripheral deposition and C/P ratios of ICS/LABA with NEXThaler versus Ellipta. NEXThaler demonstrated inspiratory flow rate independency of lung deposition versus Turbohaler. These findings suggest that the extrafine formulation is superior to large particle formulations in delivering ICS/LABA consistently both to the large and small airways.