Revised Internal Volumes of Cascade Impactors for Those Provided by Mitchell and Nagel

Copley, Mark; Smurthwaite, M.; Roberts, D.L.; Mitchell, Jolyon

doi:10.1089/jam.2005.18.364

Cited by 21 publications

(16 citation statements)

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“…Because the resistance and volume of the ACI may have a direct impact on upstream flow conditions in the compressible transient system of interest, an expanded outlet was attached to the computational models of the IP and MT. This expanded outlet is similar in diameter to the stages of the ACI and has a volume approximately equal to that of the total ACI (Copley, Smurthwaite, Roberts, & Mitchell, 2005). The resulting computational geometry for the IP model was previously reported by .…”

Section: Usp Ip and Mt Geometriesmentioning

confidence: 70%

Comparison of ambient and spray aerosol deposition in a standard induction port and more realistic mouth–throat geometry

Longest

Hindle

Choudhuri

et al. 2008

Journal of Aerosol Science

107

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Section: Usp Ip and Mt Geometriesmentioning

confidence: 70%

Comparison of ambient and spray aerosol deposition in a standard induction port and more realistic mouth–throat geometry

Longest

Hindle

Choudhuri

et al. 2008

Journal of Aerosol Science

107

View full text Add to dashboard Cite

“…In the context of DPI testing, the magnitude of the internal dead volume (open space within the assembled CI, including accessories such as the induction port or preseparator, and vacuum tubing) will influence both the time taken for particles to traverse the system and be collected, as well as the rise time for the flowrate to increase to the final value when the flow control solenoid valve is opened to initiate sampling (2). Recently, the dead volumes of the ACI, NGI and multi-stage liquid impinger (MSLI) were accurately measured with and without the various accessories (50). This information provides a useful starting point when selecting a CI for a new product.…”

Section: Dead Volumementioning

confidence: 99%

Minimizing Variability of Cascade Impaction Measurements in Inhalers and Nebulizers

Bonam

Christopher²,

Cipolla

et al. 2008

AAPS PharmSciTech

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The purpose of this article is to catalogue in a systematic way the available information about factors that may influence the outcome and variability of cascade impactor (CI) measurements of pharmaceutical aerosols for inhalation, such as those obtained from metered dose inhalers (MDIs), dry powder inhalers (DPIs) or products for nebulization; and to suggest ways to minimize the influence of such factors. To accomplish this task, the authors constructed a cause-and-effect Ishikawa diagram for a CI measurement and considered the influence of each root cause based on industry experience and thorough literature review. The results illustrate the intricate network of underlying causes of CI variability, with the potential for several multi-way statistical interactions. It was also found that significantly more quantitative information exists about impactor-related causes than about operator-derived influences, the contribution of drug assay methodology and product-related causes, suggesting a need for further research in those areas. The understanding and awareness of all these factors should aid in the development of optimized CI methods and appropriate quality control measures for aerodynamic particle size distribution (APSD) of pharmaceutical aerosols, in line with the current regulatory initiatives involving quality-by-design (QbD).

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“…This approach approximates reality as long as the volume of air sampled is significantly larger than the dead volume enclosed by the CI system. 31 Byron et al recently observed that for such DPI testing in a quality control environment, the setup has to ensure that the flow-time profile is reproducible, irrespective of which impactor, pump, or flow configuration is employed, and that there are no specific controls in the pharmacopeial methods to ensure this goal is achieved. 11 For pressurized metered dose inhaler (pMDI) testing, O'Connor and Tougas have recently highlighted ways in which CI measurement precision can be improved, citing sources of variability such as electrostatic charge on nonconducting components of the CI system, laboratory temperature, and variations in actuation rate (time between individual actuations) of the inhaler.…”

Section: Roles In Inhaler Assessmentsmentioning

confidence: 99%

In vitro and in vivo aspects of cascade impactor tests and inhaler performance: A review

2007

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The purpose of this review is to discuss the roles of cascade impactor (CI) data in inhaler assessment and to examine the relationship between aerodynamic particle size distribution (APSD) and the clinical response to inhaled drugs. A systematic literature search of studies linking APSD to clinical response was undertaken. Two distinct roles for CI-generated data were identified: (1) the control of inhaler/drug product quality; and (2) the provision of data that may be predictive of particle deposition in the respiratory tract. Method robustness is required for the former application, combined with simplicity in operation, resulting in rudimentary attempts to mimic the anatomy of the respiratory tract. The latter necessitates making the apparatus and its operation more closely resemble patient use of the inhaler. A CI cannot perfectly simulate the respiratory tract, since it operates at constant flow rate, while the respiratory cycle has a varying flow-time profile. On the basis of a review of studies linking APSD to clinical response of inhaled drugs, it is concluded that attempts to use CIgenerated data from quality control testing to compare products for bioequivalence are likely to have only limited success, as links between laboratory-measured APSD, particle deposition in the respiratory tract, and clinical response are not straightforward.

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Revised Internal Volumes of Cascade Impactors for Those Provided by Mitchell and Nagel

Cited by 21 publications

References 0 publications

Comparison of ambient and spray aerosol deposition in a standard induction port and more realistic mouth–throat geometry

Comparison of ambient and spray aerosol deposition in a standard induction port and more realistic mouth–throat geometry

Minimizing Variability of Cascade Impaction Measurements in Inhalers and Nebulizers

In vitro and in vivo aspects of cascade impactor tests and inhaler performance: A review

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