Effect of dry powder inhaler resistance on the inspiratory flow rates and volumes of cystic fibrosis patients of six years and older

Several inhaled drugs for use by cystic fibrosis (CF) patients are formulated for nebulizer use only. This therapy is time consuming and includes the risk of contamination of the nebulizers. Dry powder inhalers (DPI) can be an attractive alternative for CF drugs. Inhaled flow rate and volume, and the device resistance are important determinants for optimal dispersion of drug from a DPI. It is important to understand how these variables interact in the CF population in order to properly design a new DPI formulation targeted for these patients. The objective of this study was to assess the inspiratory variables of a representative population of CF subjects 6 years and older with varying degrees of lung disease while inhaling through resistances that simulate DPI devices. Ninety-six stable CF patients were enrolled, ages 6–54 years, FEV1 19–126% predicted. Subjects inhaled forcefully through four different resistances (0.019, 0.024, 0.038, and 0.048 kP0.5/LPM, respectively), while inspiratory time (ITDPI), p...