Lung deposition, radiolabeling, aerosols, gamma

Radiolabelling of Pharmaceutical Aerosols and Gamma Scintigraphic Imaging for Lung Deposition... 

Hak-Kim Chan, Ph.D. Senior Lecturer, Faeulty of Pharmacy, University of Sydney, New South Wales, Sydney, Australia Radiolabelling of Pharmaceutical Aerosols and Gamma Scintigraphic Imaging for Lung Deposition... 

Measurements of mucociliary clearance in lungs of healthy human subjects were performed by inhaling radiolabeled aerosol particles. Retention of these particles was measured either with a gamma-camera or other gamma-ray detectors from outside the lungs. The fast-cleared fraction of the retention function was used as an indicator of mucociliary clearance. The half-time of the mucociliary clearance in healthy humans was 4(fast) = 2-4 hr, and this fast phase of clearance was flnished after about 6-12 hr. Thus, many authors have used 24-hr clearance as a measure of airway deposition or deposition in the tracheobronchial tree. However, this is true only if all particles are cleared from intrathoracic airways by mucociliary clearance within 24 hr. If particles are retained in airways after 24 hr, they carmot be distinguished from those deposited in the peripheral lungs from where particle transport is well known to be slow (see Sec. III). 

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