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

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

Methods: 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.

Results: 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.

Conclusions: 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.