Dry powder inhalers (DPIs) are commonly prescribed for asthma and chronic obstructive pulmonary disease (COPD). During each inhalation manoeuvre, the metered dose in a DPI needs to be de-aggregated to ensure that emitted dose contains drug particles with the potential for lung deposition. Three important inhalation profile parameters maximum inhalation flow (MIF), acceleration rate (ACIM), inhalation volume (Vin) were identified to affect dose emission and drug deposition from DPIs [1]. However, which of these three parameters is the most important it is still unclear.
In this work, the COPD patient inhalation profiles were modified to change only one variable at a time from the above mentioned inhalation parameters, whilst maintaining the two other parameters constant. 9 inhalation profiles were used. They were classified into three groups. The inhalation profiles were replayed using a breath simulator (BRS) connected to an Andersen Cascade Impactor (ACI) via a mixing inlet providing supplementary air to identify the aerodynamic characteristics of the emitted dose from an indacaterol 150 μg Onbrez Breezhaler®.
The Total emitted dose (TED), fine particle dose (FPD) and residual amount (RA) were all significantly (p<0.05) affected by each of the inhalation parameters (ACIM, MIF, and Vin) but the ACIM has less significant effect (p>0.05) on the mass median aerodynamic diameter (MMAD) than the MIF. The study illustrates the importance of identifying the effect of the main inspiratory parameters on the aerodynamic characteristics of indacaterol 150μg dose emission from Onbrez Breezhaler® using altered COPD patient inhalation profiles.