Impact of Oropharyngeal Deposition on Inhaled Dose

Dolovich, Myrna; Rhem, Rod G.

doi:10.1089/jam.1998.11.suppl_1.s-112

Cited by 35 publications

(13 citation statements)

References 2 publications

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“…29 The CI is operated at constant flow rate for testing most types of inhalers. However, for dry powder inhalers (DPIs), the compendial procedures attempt to simulate an inhalation maneuver in order to operate the device so that the powder is aerosolized as a bolus, as would be the case in normal use.…”

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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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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“…Induction Port (IP): An inlet is required to ensure that the inhaler mouthpiece is oriented with respect to the CI in a fixed horizontal plane, and also to ensure that the aerosol produced is sampled in a defined manner. The IP also serves the purpose of mimicking to a greater or lesser extent depending on its design, the human oropharyngeal region (16). In its role as a model of the entrance to the respiratory tract, the IP collects almost all of the fast moving and so-called ballistic fraction of the inhaler-generated aerosol component of pMDI-produced aerosols formed by flash evaporation of the propellant, and therefore likely to deposit in the oropharynx (16).…”

Section: Contribution To Apsd Measurement Accuracy From Components Ofmentioning

confidence: 99%

“…The IP also serves the purpose of mimicking to a greater or lesser extent depending on its design, the human oropharyngeal region (16). In its role as a model of the entrance to the respiratory tract, the IP collects almost all of the fast moving and so-called ballistic fraction of the inhaler-generated aerosol component of pMDI-produced aerosols formed by flash evaporation of the propellant, and therefore likely to deposit in the oropharynx (16). The pharmacopeial design comprising a straightforward right-angle bend (4,5) is highly simplified both for ease of manufacture and to provide a standardized entry to enable side-byside comparisons of OIP aerosols to be made.…”

Section: Contribution To Apsd Measurement Accuracy From Components Ofmentioning

confidence: 99%

Good Cascade Impactor Practice (GCIP) and Considerations for “In-Use” Specifications

et al. 2013

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Abstract. The multi-stage cascade impactor (CI) is widely used to determine aerodynamic particle size distributions (APSDs) of orally inhaled products. Its size-fractionating capability depends primarily on the size of nozzles of each stage. Good Cascade Impactor Practice (GCIP) requires that these critical dimensions are linked to the accuracy of the APSD measurement based on the aerodynamic diameter size scale. Effective diameter (D eff ) is the critical dimension describing any nozzle array, as it is directly related to stage cut-point size (d 50 ). d 50 can in turn be determined by calibration using particles of known aerodynamic diameter, providing traceability to the international length standard. Movements in D eff within manufacturer tolerances for compendial CIs result in the worst case in shifts in d 50 of <±10%. Stage mensuration therefore provides satisfactory control of measurement accuracy. The accurate relationship of D eff to d 50 requires the CI system to be leak-free, which can be checked by sealing the apparatus at the entry to the induction port and isolating it from the vacuum source and measuring the rate of pressure rise before each use. Mensuration takes place on an infrequent basis compared with the typical interval between individual APSD determinations. Measurement of stage flow resistance (pressure drop; ΔP stage ) could enable the user to know that the CI stages are fit for use before every APSD measurement, by yielding an accurate measure of D eff . However, more data are needed to assess the effects of wear and blockage before this approach can be advocated as part of GCIP.

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“…In such a manner, the fraction of the dose delivered to the lungs may be estimated. Figure 6 , from Dolovich and Rhem [86] , displays seven different " throats " that have been used for this purpose. Of these, the USP -1, USP -2, and twin impinger inlet have been the most popular [87] .…”

Section: Empirical and Semiempirical Modelsmentioning

confidence: 99%

Aerosol Drug Delivery to the Lungs

Finlay

2011

Pharmaceutical Sciences Encyclopedia

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This chapter will begin with a very brief introduction to aerosol mechanics as related to the transport and deposition of inhaled drug particles throughout the respiratory tract. This familiarization then will serve as requisite background for the discussion of aerosol particle sizing instruments in use for research and development, regulatory, and quality assurance purposes, as well as for descriptions of the different types of aerosol delivery systems currently available and in development.

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Impact of Oropharyngeal Deposition on Inhaled Dose

Cited by 35 publications

References 2 publications

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

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

Good Cascade Impactor Practice (GCIP) and Considerations for “In-Use” Specifications

Aerosol Drug Delivery to the Lungs

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