Performance of dry powder inhalers with single dosed capsules in preschool children and adults using improved upper airway models.

The pulmonary administration of pharmaceutical aerosols to patients is affected by age-dependent variations in the anatomy of the upper airways and the inhalation pattern. Considering this aspect, different upper airway models, representing the geometries of adults and preschool children, and a conventional induction port according to the European Pharmacopeia were used for in vitro testing of dry powder inhalers with single dosed capsules (Cyclohaler®, Handihaler® and Spinhaler®). Deposition measurements were performed using steady flow rates of 30 and 60 L/min for the Handihaler®/Spinhaler® and 30, 60 and 75 L/min for the Cyclohaler®. The inhalation volume was set at 1 L. For the Cyclohaler®, the in vitro testing was supplemented by a pediatric inhalation profile. Slight differences of pulmonary deposition between the idealized adult (11%-15%) and pediatric (9%-11%) upper airway model were observed for the Cyclohaler®. The applied pediatric inhalation profile resulted in a reduction of pulmonary deposition by 5% compared to steady conditions and indicated the influence of the inhalation pattern on the amount of pulmonary deposited particles. The comparison of two pediatric upper airway models showed no differences. The performance of the Handihaler® was similar to the Cyclohaler®. The Spinhaler® showed an insufficient performance and limited reproducibility in our investigations.