Pressurized aerosols for oral inhalation

Morén, Folke

doi:10.1016/0378-5173(81)90022-3

Cited by 27 publications

(10 citation statements)

References 23 publications

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“…In general, it is difficult to determine the precise particle size distribution that is emitted by MDIs. 33,34 Nonetheless, LeBelle et al 35 and Crim et al 36 determined the range of particle sizes of MDIs as 1.1 to 4.7 µm using a cascade impactor. LeBelle et al 35 reported the mass median aerodynamic diameter (MMAD) and geometric standard deviation (σg) of 4 inhalers to lie between 2.28 µm (σg = 2.63) and 4.13 µm (σg = 2.19).…”

Section: Discussionmentioning

confidence: 99%

Orally Inhaled Drug Particle Transport in Computerized Models of Laryngotracheal Stenosis

Frank‐Ito

2020

Otolaryngol.--head neck surg.

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Objective Adjuvant management for laryngotracheal stenosis (LTS) may involve inhaled corticosteroids, but metered dose inhalers are designed for pulmonary drug delivery. Comprehensive analyses of drug particle deposition efficiency for orally inhaled corticosteroids in the stenosis of LTS subjects are lacking. Study Design Descriptive research. Setting Academic medical center. Methods Anatomically realistic 3-dimensional reconstructions of the upper airway were created from computed tomography images of 4 LTS subjects—2 subglottic stenosis and 2 tracheal stenosis subjects. Computational fluid dynamics modeling was used to simulate airflow and drug particle transport in each airway. Three inhalation pressures were simulated, 10 Pa, 25 Pa, and 40 Pa. Drug particle transport was simulated for 100 to 950 nanoparticles and 1 to 50 micron-particles. Particles were released into the airway to mimic varying inhaler conditions with and without a spacer chamber. Results Based on smallest to largest cross-sectional area ratio, the laryngotracheal stenotic segment shrunk by 57% and 47%, respectively, for subglottic stenosis models and by 53% for both tracheal stenosis models. Airflow resistance at the stenotic segment was lower in subglottic stenosis models than in tracheal stenosis models: 0.001 to 0.011 Pa.s/mL vs 0.024 to 0.082 Pa.s/mL. Drug depositions for micron-particles and nanoparticles at stenosis were 0.06% to 2.48% and 0.10% to 2.60% for subglottic stenosis and tracheal stenosis models, respectively. Particle sizes with highest stenotic deposition were 6 to 20 µm for subglottic stenosis models and 1 to 10 µm for tracheal stenosis models. Conclusion This study suggests that at most, 2.60% of inhaled drug particles deposit at the stenosis. Particle size ranges with highest stenotic deposition may not represent typical sizes emitted by inhalers.

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Section: Discussionmentioning

confidence: 99%

Orally Inhaled Drug Particle Transport in Computerized Models of Laryngotracheal Stenosis

Frank‐Ito

2020

Otolaryngol.--head neck surg.

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“…Upon reaching the turbinates, the airstream subsequently changes direction by approximately 90°. These anatomical features would favour inertial impaction in the anterior portion of the nose, especially for large particles emerging from an MDI at high velocity (Moren, 1981;Newman and Clarke, 1983). Since it is virtually impossible for a patient to direct the spray through the nasal valve towards the turbinates, it is likely that the majority of the dose will be deposited in the region of the valve, and will be unable to penetrate further.…”

Section: Discussionmentioning

confidence: 99%

The nasal distribution of metered does inhalers

Newman

Morén²,

Clarke

1987

J. Laryngol. Otol.

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The intranasal distribution of aerosol from a metered dose inhaler has been assessed using a radiotracer technique. Inhalers were prepared by adding 99Tcm-labelled Teflon particles (simulating the drug particles) to chlorofluorocarbon propellants, and scans of the head (and chest) taken with a gamma camera. Ten healthy subjects (age range 19–29 years) each performed two radioaerosol studies with the inhaler held in two different ways: either in a single position (vial pointing upwards) or in two positions (vial pointing upwards and then tilted by 30° in the sagittal plane).The vast majority of the dose (82.5 ± 2.8 (mean ± SEM) per cent and 80.7 ± 3.1 per cent respectively for one-position and two-position studies) was deposited on a single localized area in the anterior one-third of the nose, the initial distribution pattern being identical for each study. No significant radioaerosol was detected in the lungs. Only 18.0 ± 4.7 per cent and 15.4 ± 4.1 per cent of the dose had been removed by mucociliary action after 30 minutes, and it is probable that the remainder had not penetrated initially beyond the vestibule. Since the deposition pattern was highly localized and more than half the dose probably failed to reach the turbinates it is possible that the overall effect of nasal MDIs is suboptimal for the treatment of generalized nasal disorders.

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“…In general, the sizes of particles emitted from medical aerosol dose metered inhalers are not precisely known [13] and results are sometimes contradictory.…”

Section: Discussionmentioning

confidence: 99%

Particle size study of nine metered dose inhalers, and their deposition probabilities in the airways

Bouchikhi¹,

Becquemin²,

Bignon³

et al. 1988

Eur Respir J

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This study deals with the particle size measurement of nine aerosol metered dose inhalers. Calibration was made possible by the use of a laser particle velocimeter (aerodynamic Particle Sizer from TSI). The count median aerodynamic diameters (CMAD) show little variation, from 0.63 to 0.73 micron, with standard deviations (sigma g) between 1.2 and 1.8. Aerodynamic diameter aerosol diagram analysis showed multimodal mass distribution for all the tested dose inhalers. Calculations for the airway deposition probabilities (extrathoracic, tracheobronchial and alveolar) refer to the studies made by W. Stahlhofen and co-workers. As most aerosol metered dose inhalers have a predominantly bronchial therapeutic destination, the deposition at the bronchial level could be enhanced with the following parameters: inspired volume of 1500 ml, inspiratory time of 2 sec, aerosol mass median aerodynamic diameter (MMAD) of 7.5 microns, with a monodispersed distribution. The respective influences of the excipients and propellents used for the aerosolization of these dose metered inhalers are also discussed.

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Pressurized aerosols for oral inhalation

Cited by 27 publications

References 23 publications

Orally Inhaled Drug Particle Transport in Computerized Models of Laryngotracheal Stenosis

Orally Inhaled Drug Particle Transport in Computerized Models of Laryngotracheal Stenosis

The nasal distribution of metered does inhalers

Particle size study of nine metered dose inhalers, and their deposition probabilities in the airways

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