Effect of Flow Rate on Emitted Fine Particle Mass (FPM) from a Dry Powder Inhaler (DPI) and a Metered Dose Inhaler (MDI) with Spacer Delivering Salbutamol.

<bold>Objective:</bold> DPIs are widely prescribed for the treatment of asthma and COPD because they are perceived to be portable and easy to use. Recently they have been seen as avoiding greenhouse gas emissions from propellants used in pMDIs. However, DPIs rely on patient inhalation technique to aerosolize the powder and transport it past the upper airway. To assess how particle size and dose might be affected by patients that do not have the capability to generate sufficient inspiratory flow rates our study evaluated a DPI and a pMDI plus a spacer (designed for on-the-go use) at a range of flow rates. <bold>Methods:</bold> Easyhaler DPIs and Teva Salamol pMDIs with AeroChamber2go* spacer were assessed by Next Generation Cascade Impactor at flow rates of 15 to 60 L/min. Salbutamol was recovered quantitatively by HPLC. Results were expressed as mass <4.46µm FPM as potentially available to the lungs of the patient. <bold>Results:</bold> Fine Particle Mass (mean±sd) micrograms (µg/actuation): <table-wrap><object-id>erj;64/suppl_68/PA2110/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td>Flow Rate</td><td>15L/Min</td><td>30L/Min</td><td>60L/Min</td></tr><tr><td>DPI_FPM</td><td>1.7±0.1</td><td>13.1±1.3</td><td>30.0±3.5</td></tr><tr><td>pMDI/Spacer_FPM</td><td>58.7±3.7</td><td>59.2±4.9</td><td>66.0±6.3</td></tr></tbody></table></table-wrap> <bold>Conclusions:</bold> These data suggest a loss of performance in delivering respirable particles at both lower flowrates from the DPI, whereas little to no change occurred in FPM with the pMDI+spacer and it was approximately twice as efficient. Many patients may have the physiological capability to generate sufficient inspiratory flow rates close to 60 L/min. However, those at the extreme age range of potential users and those of all ages with severe obstructive disease or who lack the cognitive ability may fail to achieve sufficient delivery from the DPI.