Quantitative Investigation of Synthetic Mucus Effects on Spray Deposition in a 3D-Printed SLA Nasal Cavity Model

To quantify the deposition distribution of intranasally administered sprays in an anatomically accurate 3D-printed nasal model under varying conditions.

A multipiece nasal cast was used to assess deposition under three head positions (upright, 22.5° backward tilt, and 45° backward tilt) and two airflow conditions (no flow and gentle sniff). Synthetic mucus coatings were prepared using saline-based xanthan gum (XG) solutions with two different XG concentrations: 0.25% w/v, representing a healthy state, and 1% w/v, representing a diseased state. Regional doses were quantified using salinity-based measurements for both uncoated and coated nasal casts.

The results demonstrate that synthetic mucus coatings significantly altered intranasal spray dosimetry, promoting broader spreading and deeper translocation compared to dry-wall models. In the middle turbinate region, the highest mean deposition occurred under sniff airflow at a 45° backward tilt with a 1% XG coating (76 ppm), representing a 244% increase over the dry condition (22 ppm). For the posterior nasal cavity, the most effective mean deposition was achieved at a 22.5° backward tilt with sniff airflow and a 0.25% XG coating (63 ppm vs. 0 ppm dry). The mucus viscosity can significantly alter regional distribution. A 0.25% XG coating facilitated deeper translocation to the posterior nasal cavity, while 1% XG enhanced retention in the middle turbinate region.

These findings highlight the importance of incorporating synthetic mucus in in vitro nasal models to improve physiological relevance and provide insights for optimizing intranasal drug delivery techniques.