:: Section 4
DPI (Dry Powder Inhaler)
A DPI is a metered-dosing system initiated by breath, that is, the patient generates the aerosol by drawing air through a dose of drug powder. Unlike SVNs, no propellants are needed and hand-breath is not required. However, the powder needs to be dispersed into respirable particles and that will required the generation of a turbulent flow in the inhaler. Hence, the ability to inhale the powder with a high inspiratory flow rate is very critical in using the DPI, i.e., the DPI requires a high inspiratory flow rate.