On the correlation of output rate and aerodynamic characteristics in vibrating-mesh-based aqueous aerosol delivery

Aerosolization of aqueous formulations is of special interest for inhalative drug delivery, where an adequate nebulizer performance represents a prerequisite for improving pulmonary therapy. The present study investigated the interplay of output rate and aerodynamic characteristics of different excipientbased formulations and its impact on the atomization process by vibrating-mesh technology (i.e. eFlow rapid). Output rate and aerodynamic characteristics were manipulated by both dynamic viscosity and conductivity of the applied formulation. Supplementation with sucrose and sodium chloride caused a decline (down to 0.2 g/min) and elevation (up to 1.0 g/min) of the nebulizer output rate, respectively. However, both excipients were capable of decreasing the aerodynamic diameter of produced aerosol droplets from >7.0 pm to values of <5.0 pm. Thus, the correlation of output rate and aerodynamic characteristics resulted in linear fits of opposite slopes (R2 >0.85). Finally, the overall number of delivered aerosol droplets per time was almost constant for sucrose (<1 x 108 droplets/s), while for sodium chloride a concentration-dependent increase was observed (up to 3 x 108 droplets/s). Overall, the current findings illustrated the influence of formulation parameters on the aerosolization process performed by vibrating-mesh technology. Moreover, concentration and charge distribution of aerosol populations supposedly modify the final characteristics of the delivered aerosols. (C) 2013 Elsevier B.V. All rights reserved.