Regional deposition of nebulized hypodense nonisotonic solutions in the human respiratory tract.
Deposition of nonisotonic therapeutic and diagnosis aerosols can cause changes in airway fluid composition and bronchoconstriction in sensitive subjects. "Hypodense" aerosols containing a relatively low concentration of droplets in the carrier air were used in the studies of regional deposition of radiolabelled nebulized solutions of hypo- and hypertonic saline, in order to investigate whether the number of droplets per volume of carrier can affect deposition. Solutions with and without 0.5% nedocromil sodium were nebulized in order to examine the effects of a potential modifier of the rates of heat and mass transfer. The deposition was quantified using penetration index (PI) calculated from images obtained by single photon emission computerized tomography (SPECT) in 11 healthy volunteers per study. There was an increase in the penetration index (10.9%, for the saline only; 15.5%, for the nedocromil study) of the hypotonic compared to the hypertonic aerosol, although the initial size distribution of both types of aerosols was very similar (mass median aerodynamic diameter (MMAD) 3.7 and 3.8 microns; geometric standard deviation (GSD) 1.8 and 1.5 for the hypo- and hypertonic aerosols, respectively). The present results confirm the effects of tonicity on deposition of aerosols found in a parallel study reported in this issue of the Journal. They also give support to the theory that, in addition to the concentration of the nebulized solutions, the number of droplets per volume of the carrier air is a factor affecting deposition of aqueous aerosols. The presence of 0.5% nedocromil sodium in the solutions did not appear to interfere with the processes of heat and water transfer in the airways.
Dept of Pharmacy, University of Sydney, NSW, Australia.
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Chan
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Phipps
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Gonda
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Cook
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Fulton
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Young
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Bautovich
D000328:Adult; D000336:Aerosols / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D006982:Hypertonic Solutions / Q000493:pharmacokinetics; D007038:Hypotonic Solutions / Q000493:pharmacokinetics; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D009330:Nebulizers and Vaporizers; D017835:Nedocromil / Q000008:administration & dosage / Q000493:pharmacokinetics; D010316:Particle Size; D012123:Pulmonary Ventilation; D012016:Reference Values; D016284:Technetium Tc 99m Pentetate; D015899:Tomography, Emission-Computed, Single-Photon; D014132:Trachea / Q000000981:diagnostic imaging / Q000378:metabolism*; D014797:Vital Capacity
D000336:Aerosols; D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D017835:Nedocromil; D016284:Technetium Tc 99m Pentetate