The influence of actuation parameters on in vitro testing of nasal spray products

Nasal spray drug products are normally characterized via measurement of shot weight, spray pattern, plume geometry, and droplet size distribution (DSD). In this project, the actuation parameters, such as stroke length, actuation velocity, and actuation acceleration, were investigated to ascertain how they affect nasal spray characteristics. Pfeiffer nasal spray pump units filled with water were used in the study. Actuation parameters were adjusted using an electronic automated actuation system, SprayVIEW NSx. Spray pattern and plume geometry measurements were carried out using a high speed optical spray characterization system, SprayVIEW NSP, and DSD analysis was performed using a Malvern 2600 laser diffraction system. Our results show that different actuation parameters affect the nasal spray characteristics in different ways and to different degrees. Among all the actuation parameters, stroke length and actuation velocity have significant effects on the nasal spray characteristics, while the other actuation parameters have little, if any, effect. Compared to spray pattern, plume geometry and DSD, shot weight provides very little characterization information. The findings from this work suggest that, for in vitro bioavailability (BA) and bioequivalence (BE) studies of nasal spray products, the actuation parameters, stroke length, and velocity must be carefully selected. Spray pattern, plume geometry, and DSD appear to provide critical data for assessment of nasal pump performance.