Ex-vivo product performance of Diskus and Turbuhaler inhalers using inhalation profiles from patients with severe chronic obstructive pulmonary disease

Dosing performance of dry powder inhalers is dependent on patient's inspiratory effort. This study compares the inhalation profiles generated by patients with severe obstructive lung disease using Diskus and Turbuhaler inhalers. The patient profiles are subsequently used to determine the dosing performance of fluticasone propionate Diskus and budesonide Turbuhaler inhalers. Inhalation profiles were recorded in COPD patients (FEV1 < or = 30% predicted) as they inhaled with maximal effort through the inhalers. The profiles were used in an inhalation simulator to assess the dosing performance by measuring the total emitted dose and the fine particle mass for each inhaler type. Peak inspiratory flow was significantly higher through the Diskus (mean 82.31 min(-1)) compared with Turbuhaler (mean 53.51 min(-1), difference = 28.8 l min(-1); P < 0.0001). In addition, in direct comparison of the two devices. the Diskus was shown to deliver a more consistent dose irrespective of flow than the Turbuhaler in this patient population. These findings may be of importance in optimising selection of devices for patients with severe airway obstruction.