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Objective <p>The actuator orifice diameter (OD) of pressurized metered dose inhalers (pMDIs) is known to influence the plume geometry and spray pattern exiting the orifice. Actuator OD has previously been found to influence <i>in vitro</i> regional deposition in an adult extrathoracic airway model for a suspension epinephrine formulation, with smaller OD reducing oral cavity deposition. Whether this effect persists in the smaller extrathoracic airways of school-aged children is unknown.</p> Methods <p>Regional extrathoracic deposition of epinephrine from pMDIs was investigated using an idealized child mouth-throat geometry. A sectioned version of the Alberta Idealized Child Throat (AICT), divided into analogues of the oral cavity, the pharynx/larynx, and the upper trachea, was used to test pMDIs with small and large ODs (0.22 and 0.44 mm) across a range of inhalation flowrates (10, 30, 60, and 100 L/min), with two inhaler insertion angles (transverse and coaxial). In addition, the effect of increasing ambient humidity on regional extrathoracic deposition was explored with both actuator ODs.</p> Results <p>Actuator OD strongly influenced <i>in vitro</i> regional extrathoracic deposition in the child model, with the smaller OD decreasing oral cavity deposition, and increasing delivery to the laryngeal region and lungs. While increased ambient humidity influenced <i>in vitro</i> regional extrathoracic deposition, the influence of environmental changes was minor when compared with changes associated with actuator OD.</p> Conclusion <p>Overall, for the suspension epinephrine formulation tested, the reduction in oral cavity deposition observed for the smaller OD actuator was maintained despite varying extrathoracic airway size (child <i>vs.</i> adult) and varying ambient humidity.</p>

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Regional Extrathoracic Deposition of Inhaled Epinephrine in an Idealized Child Airway: Influence of Pressurized Metered Dose Inhaler Actuator Orifice Diameter

  • 期刊论文

  • 发表日期：

    2026年2月20日

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  • Kineshta Pillay,
  • Scott Tavernini,
  • Conor A. Ruzycki,
  • George H. Luciuk,
  • Kevin W. Stapleton,
  • Warren H. Finlay,
  • Andrew R. Martin

摘要

Objective

The actuator orifice diameter (OD) of pressurized metered dose inhalers (pMDIs) is known to influence the plume geometry and spray pattern exiting the orifice. Actuator OD has previously been found to influence in vitro regional deposition in an adult extrathoracic airway model for a suspension epinephrine formulation, with smaller OD reducing oral cavity deposition. Whether this effect persists in the smaller extrathoracic airways of school-aged children is unknown.

Methods

Regional extrathoracic deposition of epinephrine from pMDIs was investigated using an idealized child mouth-throat geometry. A sectioned version of the Alberta Idealized Child Throat (AICT), divided into analogues of the oral cavity, the pharynx/larynx, and the upper trachea, was used to test pMDIs with small and large ODs (0.22 and 0.44 mm) across a range of inhalation flowrates (10, 30, 60, and 100 L/min), with two inhaler insertion angles (transverse and coaxial). In addition, the effect of increasing ambient humidity on regional extrathoracic deposition was explored with both actuator ODs.

Results

Actuator OD strongly influenced in vitro regional extrathoracic deposition in the child model, with the smaller OD decreasing oral cavity deposition, and increasing delivery to the laryngeal region and lungs. While increased ambient humidity influenced in vitro regional extrathoracic deposition, the influence of environmental changes was minor when compared with changes associated with actuator OD.

Conclusion

Overall, for the suspension epinephrine formulation tested, the reduction in oral cavity deposition observed for the smaller OD actuator was maintained despite varying extrathoracic airway size (child vs. adult) and varying ambient humidity.