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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: 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.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 forces acting on the API particle.
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f0045: The forces acting on the API particle.

Mentions: Fig. 9 illustrates the forces acting on the ith spherical API particle (Eq. (1)), in which fci_n and fci_t are the normal and tangential components of the contact force fci, respectively. Once the air flow is introduced, the air–particle interaction force fapi drags the API particle to a positive y position, since the component in the positive y direction of fapi is dominant. If the API particle is located in the upstream hemisphere of the spherical carrier particle (i.e., 90°≤α≤180°), the air–particle interaction force fapi actually compresses the API particle to the carrier. If the API particle is located in the downstream hemisphere (i.e., 0°≤α≤90°), the air–particle interaction forces fapi actually pull the API particle away from the carrier. When the normal component of the air–particle interaction force fapi is larger than the pull-off force Fc (Eq. (3), the API particle can be removed from the carrier. In addition, due to the effects of the tangential component of the air–particle interaction force fapi and the torque caused by the tangential component of the contact force, fci_t, the API particles located in the upstream hemisphere can move (either slide or roll) to the downstream hemisphere and then be removed from the carrier. This process is also clearly shown in the snapshots in Fig. 2. Therefore, the API particles in the downstream regions of the spherical carrier particle are more likely to be removed by air flow.


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 forces acting on the API particle.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

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

f0045: The forces acting on the API particle.
Mentions: Fig. 9 illustrates the forces acting on the ith spherical API particle (Eq. (1)), in which fci_n and fci_t are the normal and tangential components of the contact force fci, respectively. Once the air flow is introduced, the air–particle interaction force fapi drags the API particle to a positive y position, since the component in the positive y direction of fapi is dominant. If the API particle is located in the upstream hemisphere of the spherical carrier particle (i.e., 90°≤α≤180°), the air–particle interaction force fapi actually compresses the API particle to the carrier. If the API particle is located in the downstream hemisphere (i.e., 0°≤α≤90°), the air–particle interaction forces fapi actually pull the API particle away from the carrier. When the normal component of the air–particle interaction force fapi is larger than the pull-off force Fc (Eq. (3), the API particle can be removed from the carrier. In addition, due to the effects of the tangential component of the air–particle interaction force fapi and the torque caused by the tangential component of the contact force, fci_t, the API particles located in the upstream hemisphere can move (either slide or roll) to the downstream hemisphere and then be removed from the carrier. This process is also clearly shown in the snapshots in Fig. 2. Therefore, the API particles in the downstream regions of the spherical carrier particle are more likely to be removed by air flow.

Bottom Line: 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.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