There is currently no in vitro technique for assessing plume geometry of nasal sprays under airflow conditions. However, a majority of FDA approved nasal products recommend that patients inhale during actuation. Therefore, a reproducible in vitro test that measures plume angles under physiologically relevant inhalation flow rates would be useful. The purpose of this study was to adapt the recently described Plume Induction Port Evaluator (PIPE) apparatus for nasal sprays under flow and correlate these with nasal cast deposition patterns.
Mass Median Plume Angles (MMPAs) of four nasal spray formulations with increasing viscosities were determined using the PIPE apparatus in the absence and presence of airflow. MMPAs were then correlated to drug deposition within 3D printed nasal casts using airflow. We evaluated different inhalation instructions obtained from the package insert of nasal products.
MMPAs significantly reduced (narrower angles) when using flow for the three formulations with the lowest viscosities. An increase in the turbinate deposition was observed in the nasal casts when just one of the nostrils was closed during inhalation, except by the highest viscosity formulation. The turbinate deposition numerically correlated with changes in the plume angles observed using PIPE.