Drug deposition from dry powder inhalers is dependent on each patient’s inspiratory effort. The aim of this study was to use the inhalation profiles generated by COPD patients when they used a 200 µg budesonide plus 6 µg formoterol Symbicort^® Tubuhaler^® to determine the characteristics of the dose they would have inhaled. Inhalation profiles were recorded in COPD patients as they inhaled deeply and forcefully through an empty Symbicort^® Tubuhaler^® according to the instructions given in the patient information leaflet (PIL).The profiles were replayed by a breath simulator (BRS) using ex-vivo methodology including the Andersen cascade Impactor to identify the total emitted dose (TED), fine particle dose (FPD) and mass median aerodynamic diameter (MMAD) of the dose emitted from the inhaler.

We have adapted the compendial method for the Andersen Cascade Impactor (ACI) to include a mixing inlet providing supplementary air to determine the aerodynamic dose emission characteristics of 200 µg budesonide plus 6 µg formoterol Symbicort^® Tubuhaler^® using COPD patient inhalation profiles. The results, using this ex-vivo methodology, demonstrate that increasing the inspiratory flow rate clearly increases the TED and FPD. Also, the effect of inhalation volume is pronounced for patient groups that generated low and intermediate inspiratory flow rates (groups 1 and 2) compared to group those with higher flows (group 3).The result show that the deaggregation of the powder formulation is affected by the peak inhalation flow rate (PIF) and the inhalation volume (IV). The results show the value of this ex-vivo method to identify the type of dose the patient would have inhaled during real life use.