Transport and deposition of cohesive pharmaceutical powders in human airway

Abstract

Abstract. Pharmaceutical powders used in inhalation therapy are in the size range of 1-5 microns and are usually cohesive. Understanding the cohesive behaviour of pharmaceutical powders during their transportation in human airway is significant in optimising aerosol drug delivery and targeting. In this study, the transport and deposition of cohesive pharmaceutical powders in a human airway model is simulated by a well-established numerical model which combines computational fluid dynamics (CFD) and discrete element method (DEM). The van der Waals force, as the dominant cohesive force, is simulated and its influence on particle transport and deposition behaviour is discussed. It is observed that even for dilute particle flow, the local particle concentration in the oral to trachea region can be high and particle aggregation happens due to the van der Waals force of attraction. It is concluded that the deposition mechanism for cohesive pharmaceutical powders, on one hand, is dominated by particle inertial impaction, as proven by previous studies; on the other hand, is significantly affected by particle aggregation induced by van der Waals force. To maximum respiratory drug delivery efficiency, efforts should be made to avoid pharmaceutical powder aggregation in human oral-to-trachea airway.

Image-based modelling of inhaler deposition during respiratory exacerbation

“…This is a speculative explanation as our results in Figure 5 show small variation with cohesive forces. The minor influence of cohesion in our simulations is aligned with the small localised changes shown by Wang et al (2017) when modelling cohesion. As suggested by Islam et al (2020) the effect of particle-particle interactions should be investigated across many cases to understand their influence on respiratory drug delivery, but our study has provided a first step towards this.…”

“…This was as cohesive van der Waals forces have been known to influence the transport of micro-scale particles (Gu et al, 2016a). Soft-sphere (treating particles as deformable) deposition studies have been implemented before but only to observe dynamics in simplified airways (Chen et al, 2012; Wang et al, 2017). This allows understanding of particle dynamics in a fixed system.…”

“…This was as cohesive van der Waals forces have been known to influence the transport of micro-scale particles (Gu et al, 2016a). Soft-sphere (treating particles as deformable) deposition studies have been implemented before but only to observe dynamics in simplified airways (Chen et al, 2012;Wang et al, 2017). We conclude that the computational cost of DEM is too large to be feasible for further study in broad patient populations with varying inhalation parameters and drug properties (particularly smaller particles).…”

A combined CFD-based simulation and experimental study of particle dispersion in a high-concentration airtight space under unorganized airflow

“…With advantages such as high utilization of spraying materials, rapid construction speed and safety, thermal spraying and electrostatic spraying have been widely promoted in various countries in recent years. Spray technology plays an essential role in the engineering field and attracts a large amount of research based on Computational Fluid Dynamics (CFD), including studies of powder transport behavior, [1][2][3] powder concentration distribution 4,5 and spraying process. 6,7 It is significant to obtain the particle distribution data for workpiece processing.…”