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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

Polar histograms of the contact orientations distribution (R=26.25 µm, Γ=0.2 mJ/m2). (a) V=1 m/s, (b) V=2 m/s, and (c) V=3 m/s and (d) V=4 m/s.
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f0025: Polar histograms of the contact orientations distribution (R=26.25 µm, Γ=0.2 mJ/m2). (a) V=1 m/s, (b) V=2 m/s, and (c) V=3 m/s and (d) V=4 m/s.

Mentions: The distribution of contact normal orientations for the carrier particle is presented in Fig. 5, which shows the polar histogram37 of the proportion of contact normal orientations falling within a series of adjacent orientation classes that partition the full orientation space. The unit circle representing the 0–360° full orientation space is partitioned into twelve bands in order to accommodate the contact normal orientations for the contacts between the carrier and API particles. Each contact is interrogated to identify its location in one of the twelve bands. If a contact is located in band , the total contact number for this band is increased by one. After all contacts have been scanned, the contact number of band when the dispersion process is completed, ni, and the original contact number of band when the agglomerate is formed, Ni can be obtained. The radial coordinate of band i, ri is then determined as(13)ri=niNireferring to Eq. (11), is equal to the retention ratio for band .


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)

Polar histograms of the contact orientations distribution (R=26.25 µm, Γ=0.2 mJ/m2). (a) V=1 m/s, (b) V=2 m/s, and (c) V=3 m/s and (d) V=4 m/s.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

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

f0025: Polar histograms of the contact orientations distribution (R=26.25 µm, Γ=0.2 mJ/m2). (a) V=1 m/s, (b) V=2 m/s, and (c) V=3 m/s and (d) V=4 m/s.
Mentions: The distribution of contact normal orientations for the carrier particle is presented in Fig. 5, which shows the polar histogram37 of the proportion of contact normal orientations falling within a series of adjacent orientation classes that partition the full orientation space. The unit circle representing the 0–360° full orientation space is partitioned into twelve bands in order to accommodate the contact normal orientations for the contacts between the carrier and API particles. Each contact is interrogated to identify its location in one of the twelve bands. If a contact is located in band , the total contact number for this band is increased by one. After all contacts have been scanned, the contact number of band when the dispersion process is completed, ni, and the original contact number of band when the agglomerate is formed, Ni can be obtained. The radial coordinate of band i, ri is then determined as(13)ri=niNireferring to Eq. (11), is equal to the retention ratio for band .

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