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Three-dimensional DEM-CFD analysis of air-flow-induced detachment of API particles from carrier particles in dry powder inhalers.

Yang J, Wu CY, Adams M - Acta Pharm Sin B (2014)

Bottom Line: Hence, an understanding of these mechanisms is critical for the development of DPIs.A carrier-based agglomerate is initially formed and then dispersed in a uniformed air flow.It is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance, which is governed by the ratio of the fluid drag force to the pull-off force.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK ; Department of Chemical and Process Engineering, University of Surrey, Guildford GU2 7XH, UK.

ABSTRACT
Air flow and particle-particle/wall impacts are considered as two primary dispersion mechanisms for dry powder inhalers (DPIs). Hence, an understanding of these mechanisms is critical for the development of DPIs. In this study, a coupled DEM-CFD (discrete element method-computational fluid dynamics) is employed to investigate the influence of air flow on the dispersion performance of the carrier-based DPI formulations. A carrier-based agglomerate is initially formed and then dispersed in a uniformed air flow. It is found that air flow can drag API particles away from the carrier and those in the downstream air flow regions are prone to be dispersed. Furthermore, the influence of the air velocity and work of adhesion are also examined. It is shown that the dispersion number (i.e., the number of API particles detached from the carrier) increases with increasing air velocity, and decreases with increasing the work of adhesion, indicating that the DPI performance is controlled by the balance of the removal and adhesive forces. It is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance, which is governed by the ratio of the fluid drag force to the pull-off force.

No MeSH data available.


Related in: MedlinePlus

The agglomeration process: (a) initial setup and (b) prepared carrier–API agglomerate.
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f0005: The agglomeration process: (a) initial setup and (b) prepared carrier–API agglomerate.

Mentions: Initially, a carrier particle with a radius R and 242 API particles with radii r randomly positioned around the carrier are generated (Fig. 1a). Then the API particles are set to move towards the centre of the carrier at a specified velocity until they attach to the carrier and reach a stable state (Fig. 1b). The work of adhesion between the carrier particle and API particles is initially set to a relatively high value during this attachment process and then reduced to the required value that is used for the simulation. Thereafter, the carrier–API agglomerate is subject to a uniform flow field with a specific velocity V and gravity is introduced; consequently, both the carrier particle and the API particles move due to the resultant forces. The fluid domain is 1260 µm long, 1260 µm wide and 2100 µm high. The lower boundary is set as the gas inlet velocity, and the upper boundary is set as a continuous outflow outlet, whereas the other boundaries are set as non-slip impermeable walls. The fluid cell size is twice as large as the size of the carrier. The particle and fluid properties used in the simulation are listed in Table 1. It is assumed that the carrier and API particles have the same material properties as that of α-lactose monohydrate34. Owing to the relatively small air flow rate in current cases, small works of adhesion are chosen, which are still comparable with the experimental results measured using AFM by Louey et al.35, ranging from 0.3 to 0.9 mJ/m2.


Three-dimensional DEM-CFD analysis of air-flow-induced detachment of API particles from carrier particles in dry powder inhalers.

Yang J, Wu CY, Adams M - Acta Pharm Sin B (2014)

The agglomeration process: (a) initial setup and (b) prepared carrier–API agglomerate.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590728&req=5

f0005: The agglomeration process: (a) initial setup and (b) prepared carrier–API agglomerate.
Mentions: Initially, a carrier particle with a radius R and 242 API particles with radii r randomly positioned around the carrier are generated (Fig. 1a). Then the API particles are set to move towards the centre of the carrier at a specified velocity until they attach to the carrier and reach a stable state (Fig. 1b). The work of adhesion between the carrier particle and API particles is initially set to a relatively high value during this attachment process and then reduced to the required value that is used for the simulation. Thereafter, the carrier–API agglomerate is subject to a uniform flow field with a specific velocity V and gravity is introduced; consequently, both the carrier particle and the API particles move due to the resultant forces. The fluid domain is 1260 µm long, 1260 µm wide and 2100 µm high. The lower boundary is set as the gas inlet velocity, and the upper boundary is set as a continuous outflow outlet, whereas the other boundaries are set as non-slip impermeable walls. The fluid cell size is twice as large as the size of the carrier. The particle and fluid properties used in the simulation are listed in Table 1. It is assumed that the carrier and API particles have the same material properties as that of α-lactose monohydrate34. Owing to the relatively small air flow rate in current cases, small works of adhesion are chosen, which are still comparable with the experimental results measured using AFM by Louey et al.35, ranging from 0.3 to 0.9 mJ/m2.

Bottom Line: Hence, an understanding of these mechanisms is critical for the development of DPIs.A carrier-based agglomerate is initially formed and then dispersed in a uniformed air flow.It is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance, which is governed by the ratio of the fluid drag force to the pull-off force.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK ; Department of Chemical and Process Engineering, University of Surrey, Guildford GU2 7XH, UK.

ABSTRACT
Air flow and particle-particle/wall impacts are considered as two primary dispersion mechanisms for dry powder inhalers (DPIs). Hence, an understanding of these mechanisms is critical for the development of DPIs. In this study, a coupled DEM-CFD (discrete element method-computational fluid dynamics) is employed to investigate the influence of air flow on the dispersion performance of the carrier-based DPI formulations. A carrier-based agglomerate is initially formed and then dispersed in a uniformed air flow. It is found that air flow can drag API particles away from the carrier and those in the downstream air flow regions are prone to be dispersed. Furthermore, the influence of the air velocity and work of adhesion are also examined. It is shown that the dispersion number (i.e., the number of API particles detached from the carrier) increases with increasing air velocity, and decreases with increasing the work of adhesion, indicating that the DPI performance is controlled by the balance of the removal and adhesive forces. It is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance, which is governed by the ratio of the fluid drag force to the pull-off force.

No MeSH data available.


Related in: MedlinePlus