Abstract
This paper reviews scientific understandings relevant to the dry powder inhaler (DPI) development including turbulent airflow characteristics in the inhaler, microparticle entrainment and deaggregation within the airflow and device. Using standardized entrainment tubes (SETs) and powder aerosol deaggregation equation (PADE), the aerosol performance profile in a shear stress range defined by SETs can be predicted. However, such predictions are based on the hypothesis that the shear stresses characterized from SETs are readily translatable to those of the DPIs’. Two selected model DPIs (Rotahaler and Aerolizer) with either gelatin or HPMC capsules were used to evaluate the FPF at the DPI shear stresses. The performance result using DPIs was close to the predicted FPF using SETs and PADE method. The application of SETs and PADE method can be used for performance prediction of these DPIs.
