Assessing the performance of two dry powder inhalers in preschool children using an idealized pediatric upper airway model.

High prevalence of pulmonary diseases in childhood requires inhalable medication even for young children. Little is known about the efficiency of aerosol therapy especially in preschool children. One factor which limits the lung dose is the upper airway geometry. Based on clinical data a recently developed idealized pediatric upper airway model (children 4-5 years) was used to investigate the performance of two dry powder inhalers (Easyhaler and Novolizer). In vitro investigations were first examined using steady flow rates and an inhalation volume of 1L. Chosen flow rates were 28, 41 and 60L/min (Easyhaler) and 45, 60 and 75L/min (Novolizer). Afterwards inhalation profiles simulated by an electronic lung were included. The investigations showed high amounts of drug particles (up to 80%) which were deposited in the upper airway model. The pulmonary deposition in vitro using the Easyhaler was about 28% (28-60L/min) and 22% (inhalation profile). Using the Novolizer in vitro pulmonary doses of 8-12% (45-75L/min) and about 5% (inhalation profile) were observed. The idealized model shows good performance reproducibility of dry powder inhalers. We have shown that age-dependent models might be appropriate tools for formulation and device development in pediatric age groups.