Effect of airway disease on drug deposition in the lung
Chantal Darquenne1
1University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0623, USA
Summary
Drug inhalation is a mainstay in the management of respiratory diseases. Its success not only depends on the pharmacology of the drugs being inhaled but also on the site and extent of deposition in the respiratory tract. Such deposition is tightly related to the physical properties of the inhaled aerosols (shape, size, density, electrostatic charge) and to the characteristics of the subject (lung geometry and size, breathing pattern, disease state). The most relevant deposition mechanisms for pharmaceutical aerosols are inertial impaction, a velocity-dependent mechanism, and gravitational sedimentation, a time-dependent mechanism. Increasing airflow rates increase the efficiency of deposition by inertial impaction and decreases that by sedimentation while increasing tidal volumes allow particles to reach more distal regions of the lung, where deposition by sedimentation is likely to occur.