Assessing the variability of in silico lung deposition predictions when inhaling from soft mist inhalers with various air flow resistances

Authors: Nicolas A. Buchmann, Bernhard Muellinger

Event: RDD 2024, 5-9th May 2024, Tucson, Arizona

Abstract: When selecting a suitable inhaler for effective drug delivery, it is crucial to consider both particle/droplet size and inspiratory flow rate achievable with a specific device.

Inspiratory flow rate varies significantly among inhalers due to different flow resistance. Novel SMIs, such as the pre- filled syringe SMI (PFSI®) offer a customisable range of flow resistances to suit specific patient populations.

Slow and deep inhalation is known to result in high lung deposition and determining the optimal device resistance is a critical design consideration. This study assesses inspiratory flow patterns and drug lung deposition of healthy volunteers and patients with pulmonary arterial hypertension (PAH) using SMIs with different flow resistance.

Conclusions of the Publication:

• Inhalers featuring different flow resistances
  influence the inhalation flow profile of patients.
• Measurements a lung deposition modelling
  indicate that inhalation at higher flow resistance leads to more consistent flow profiles and higher lung dose with lower patient to patient variability.
• All study subjects were able to perform appropriate inhalation manoeuvres at all flow resistances with AIT of 6–10 seconds, with AIF of 12.2–30.4 L/min and AIV of 1.3–2.9 L.
• Small differences in lung deposition are observed for different particle size distributions.
• Emphasizing good inhalation technique is crucial for effective treatment. Selecting an inhaler device such as the PFSI® soft mist inhaler with customizable flow resistance is thus important for predictable aerosol delivery to the lungs.