Deposition of Dry Powder Generated by Solovent in Sophia Anatomical Infant Nose-Throat (SAINT) Model

Purpose: To quantify deposition of (99m)technetium-labeled powder in the Sophia Anatomical Infant Nose-Throat (SAINT) model of a 9-month old. Methods: Powder was generated by the Solovent (BD Technologies), an active dry powder inhaler with spacer, during 30 seconds of tidal volume (TV) breathing. Activity that passed through the model was captured on a filter and represented powder that was available for deposition in the lungs. Deposition in the nasal cavity, on the filter, and in the spacer was expressed as a percentage of the injected dose into the spacer. Results: Mean (+/- SD) injected dose averaged 89.5 +/- 0.09%, 90.3 +/- 0.11%, and 91.3 +/- 0.05% at 50, 100, and 200 mL TV, respectively. Mean nasal deposition increased significantly from 50 mL to 100 mL and 200 mL TV with 0.60 +/- 0.002%, 1.72 +/- 0.007%, and 6.75 +/- 07.21%, respectively (all p <= 0.05). Similarly, mean filter deposition increased significantly from 50 mL to 100 mL to 200 mL with 0.28 +/- 0.00%, 1.14 +/- 0.00%, and 3.87 +/- 0.01%, respectively (all p < 0.05). Mean retention in the spacer was similar at 50 mL (93.38 +/- 0.02%) and at 100 mL TV (89.97 +/- 0.04%), but decreased significantly to 71.47 +/- 0.05% at 200 mL TV (all p < 0.05). Conclusions: These data suggest for the first time the feasibility of delivering a dry powder formulation to infants and toddlers by actively introducing the powder into a spacer. Lung deposition and nasal deposition, as a percent of injected dose, were dependent on tidal volume with deposition increasing with increasing TV. Nevertheless, deposition, as a percent of injected dose, was low in both regions. This was likely due to significant retention in the spacer at all 3 tidal volumes.