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®

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 (V-in) 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 (R) Turbuhaler (R). They have been used to identify the dose emission characteristics from a fixed dosed combination of 200 mu g budesonide plus 611,mu g formoterol Turbuhaler (R). To isolate each inhalation parameter some profiles were modified to provide a further 9 profiles to study the influence of V-in, 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. (C) 2017 Elsevier B.V. All rights reserved.