Numerical study on the effect of individual variations on inhaled drug particle deposition distribution in grouped realistic inhaler-airway models

Inhaled administration is essential for treating asthma, lung cancer and chronic obstructive pulmonary disease (COPD). Breezhaler®, as a low-resistance dry powder inhaler device, has shown excellent performance. Investigating the impact of different airway structures on the deposition mechanisms of Breezhaler® drugs in various characteristic zones is essential for improving inhaler designs and predicting the particle deposition distribution. The primary aim of this study is to systematically examine how individual differences impact the particle distribution and deposition mechanisms in different areas within the inhaler-airways. CFD was conducted to analyze the airflow pattern within these models. DPM was utilized to track the deposition paths of particles. Fourteen realistic airway models with inhalation devices were reconstructed, and the effects of three distinct inhalation airflow rates and particle sizes were analyzed. The results showed that the curvature of the airway and the length of the pharynx increased the likelihood of particle deposition. When the glottis structure had small cross-sectional tips, it caused uneven velocity distribution, but increasing the circularity and equivalent diameter of the glottis could mitigate this effect. For treating deep lung diseases like COPD, a lower inhalation flow rate makes particle size less critical, while higher flow rates require smaller particle sizes for optimal treatment. For bronchiectasis treatment targeting the tracheobronchial region, users with lower inhalation flow rates should use 4 μm particles, and those with higher flow rates should use 2 μm particles. Model 1 shows potential as a representative model for predicting deposition distribution.