Deposition, Imaging, and Clearance: What Remains to be Done?
- 1 December 2010
- journal article
- review article
- Published by Mary Ann Liebert Inc in Journal of Aerosol Medicine and Pulmonary Drug Delivery
- Vol. 23 (S2), S39-39
- https://doi.org/10.1089/jamp.2010.0839
Abstract
Deposition and clearance studies are used during product development and in fundamental research. These studies mostly involve radionuclide imaging, but pharmacokinetic methods are also used to assess the amount of drug absorbed through the lungs, which is closely related to lung deposition. Radionuclide imaging may be two-dimensional (gamma scintigraphy or planar imaging), or three-dimensional (single photon emission computed tomography and positron emission tomography). In October 2009, a group of scientists met at the “Thousand Years of Pharmaceutical Aerosols” conference in Reykjavik, Iceland, to discuss future research in key areas of pulmonary drug delivery. This article reports the session on “Deposition, imaging and clearance.” The objective was partly to review our current understanding, but more importantly to assess “what remains to be done?” A need to standardize methodology and provide a regulatory framework by which data from radionuclide imaging methods could be compared between centers and used in the drug approval process was recognized. There is also a requirement for novel radiolabeling methods that are more representative of production processes for dry powder inhalers and pressurized metered dose inhalers. A need was identified for studies to aid our understanding of the relationship between clinical effects and regional deposition patterns of inhaled drugs. A robust methodology to assess clearance from small conducting airways should be developed, as a potential biomarker for therapies in cystic fibrosis and other diseases. The mechanisms by which inhaled nanoparticles are removed from the lungs, and the factors on which their removal depends, require further investigation. Last, and by no means least, we need a better understanding of patient-related factors, including how to reduce the variability in pulmonary drug delivery, in order to improve the precision of deposition and clearance measurements.Keywords
This publication has 100 references indexed in Scilit:
- Application of Three-Dimensional Airway Algorithms in a Clinical StudyProceedings of the American Thoracic Society, 2008
- Deposition-Dependent Normal Ranges for Radioaerosol Assessment of Lung Mucus ClearanceJournal of Aerosol Medicine and Pulmonary Drug Delivery, 2008
- An Analytical Technique to Recover the Third Dimension in Planar Imaging of Inhaled Aerosols—(2) Estimation of the Deposition per Airway GenerationJournal of Aerosol Medicine, 2007
- Re-evaluation of pulmonary titanium dioxide nanoparticle distribution using the "relative deposition index": Evidence for clearance through microvasculatureParticle and Fibre Toxicology, 2007
- Methods to determine lung distribution of inhaled drugs – could gamma scintigraphy be the gold standard?British Journal of Clinical Pharmacology, 2000
- Deposition and Disposition of [C]Zanamivir Following Administration as an Intranasal SprayClinical Pharmacokinetics, 1999
- In Vitro Measurements of Delivery of Medications from MDIs and Spacer DevicesJournal of Aerosol Medicine, 1996
- Difference in pulmonary absorption of inhaled terbutaline in healthy smokers and non-smokers.Thorax, 1991
- Editorial Is 24 Hour Lung Retention an Index of Alveolar Deposition?Journal of Aerosol Medicine, 1988
- The normal human lung: ultrastructure and morphometric estimation of diffusion capacityRespiration Physiology, 1978