Aerodynamically Driven Translocation of Non-newtonian Fluids: the Relevance for Intranasal Drug Delivery

Abstract

Intranasal drug delivery depends on the effective and possibly homogenous application of medical solution on the whole surface of nasal cavity (NC). As known from previous studies, droplets of sprayed medicine administered from an atomizer can penetrate only to the very anterior parts of the NC. This study demonstrates the possibility of translocation of liquid droplets due to interactions with air flowing through a shallow channel used as a model of nasal airspaces. The liquids used in the study are non-Newtonian to simulate the properties of real pharmaceutical formulation used in modern nasal drugs. The experimental data confirmed that aerodynamic shear forces induced by the airflow facilitate translocation of droplets of non-Newtonian fluids along the horizontal channel and this displacement is characterized by dynamic motion of droplets, in contrast to a steady spreading observed in the case of a viscous Newtonian fluid. The displacement pattern depends on the rheological characteristics of liquid, airflow rate, and also on the wettability of the wall. The results obtained in this study indirectly confirm that the inhalation airflows in the nasal channels should allow to spread the deposited liquid drugs to the distal parts of NC, providing the mechanism of more homogeneous drug distribution on the nasal surface.