Tuning the Orbital® DPI device: how to control delivery parameters and aerosol performance via modification of puck orifice geometry

The current study presents a new approach to tackle high dose lung delivery using a prototype multi-breath Orbital® DPI. One of the key device components is the ‘puck’ (aerosol sample chamber) with precision-engineered outlet orifice(s) that control the dosing rate. The influence of puck orifice geometry and hole number on the performance of mannitol aerosols were studied. Pucks with different orifice configurations were filled with 400 mg of spray-dried mannitol and tested in the Orbital® DPI prototype. The emitted dose and overall aerodynamic performance across a number of ‘breaths’ were studied using a MSLI. The aerosol performances of the individual actuations were investigated using in-line laser diffraction. The emptying rate of all pucks were linear between 20-80% cumulative drug released (R2 > 0.98) and the amount of formulation released per breath could be controlled such that the device was empty after 2 to 11 breath maneuvers. The puck-emptying rate linearly related to the orifice hole length (R2 > 0.95). Mass median aerodynamic diameters of the emitted aerosol ranged from 4.03 to 4.62 µm and FPF (≤ 6.4 µm) were 50-66%. Laser-diffraction suggested that the aerosol performance and emptying rates were not dependent on breath number, showing consistent size distribution profiles.