Real life dose emission characterization using COPD patient inhalation profiles when they inhaled using a fixed dose combination (FDC) of the medium strength Symbicort® Turbuhaler®

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Graphical abstractThe aerodynamic dose emission characteristics of a fixed dose combination of a 200 μg budesonide and 6 μg formoterol Turbuhaler have been measured using methodology designed to use inhalation profiles of patients to identify the real life dose they would have inhaled. The results show that the dose emission characteristics were solely dependent on the peak inhalation flow (PIF) of each inhalation profile as shown in Figs. 1 and 2. The inhaled volume and acceleration of the inhalation flow had only a small, non-significant effect on dose emissions.The formoterol (Fig. 1) and budesonide (Fig. 2) fine particle dose (FPD) for the peak inhalation flow (PIF) of each inhalation profile.The dose emitted from dry powder inhalers (DPI) is inhalation flow dependent and so varies with the peak inhalation flow (PIF) of a patient’s inhalation maneuver (IM). Dose emission could also be affected by other IM parameters-the inhaled volume (Vin) and the initial acceleration rate of the IM (ACIM). We have adapted the compendial method for in-vitro DPI determinations so that inhalation profiles replace the inhalation square profile generated by a vacuum pump. These real-life patient inhalation profiles were measured when 18 COPD patients inhaled through an empty placebo Symbicort® Turbuhaler®. They have been used to identify the dose emission characteristics from a fixed dosed combination of 200 μg budesonide plus 6 μg formoterol Turbuhaler®. To isolate each inhalation parameter some profiles were modified to provide a further 9 profiles to study the influence of Vin and 27 to identify the effect of ACIM. The fine particle dose, total emitted dose and mass median aerodynamic diameter were significantly (p < 0.05) influenced by PIF (p < 0.05) whereas ACIM and Vin had only a small effect. The results show the value of this ex-vivo methodology to provide an insight into the dose that each patient would have inhaled during real-life use.

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