Spiral mouthpiece design in a dry powder inhaler to improve aerosolization

This study presents the effect of a spiral mouthpiece design in a carrier-based dry powder inhalation on particle aerosol characteristics. Two kinds of mouthpieces, with spiral and non-spiral shaped flow channels, were fabricated by 3D-printing; particle image velocimetry and Anderson cascade impactor were performed to evaluate the drug aerosol characteristics. The obtained experimental results were in agreement with the simulation results of the computational fluid dynamics analysis. The spiral channel created a strong swirl motion of the air flow emitted from the mouthpiece exit, which produced angular momentum rather than the axial flow velocity in the forward direction. This is beneficial in terms of liberating the micronized drug particles from the carrier surface, and leads to more effective delivery of these drug particles to the peripheral target regions of the respiratory system. The spiral device could produce drug particles with significantly smaller mass median aerodynamic diameters and higher fine particle fraction than the non-spiral device.