In Vitro/In Vivo Comparisons in Pulmonary Drug Delivery
Publication: Journal of Aerosol Medicine and Pulmonary Drug Delivery
Volume 21, Issue Number 1
Abstract
Establishing clear relationships between in vitro and in vivo data for inhaled drug products is an important goal. In vitro aerodynamic particle size distributions (APSDs) are expected to have some predictive power not only for drug deposition, but also for clinical effects. APSD data obtained by cascade impaction have been compared with lung deposition data measured in gamma scintigraphy studies. Whole-lung deposition correlated significantly with fine particle fraction (FPF) across a range of inhaler devices. FPF, defined in terms of aerosol <5.8 μm or <6.8 μm diameter, systematically overestimated lung deposition for virtually all inhalers. Lung deposition showed closer numerical equivalence to the percentage of the aerosol dose smaller than 3 μm diameter. Correlations exist between APSD data and whole-lung deposition, which may allow the greater use of APSD data for comparing inhaler devices. Agreement between in vitro and in vivo data may be improved by measuring APSD in ways that more closely mimic clinical use, including the use of impactor inlets that simulate the human upper airway anatomy. At the present time there are few published data that relate APSD to the clinical response of inhaled drugs in an unambiguous way.
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Journal of Aerosol Medicine and Pulmonary Drug Delivery
Volume 21 • Issue Number 1 • March 2008
Pages: 77 - 84
PubMed: 18518834
Copyright
Mary Ann Liebert, Inc.
History
Published online: 8 March 2008
Published in print: March 2008
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