Respiratory tract defence mechanisms

Aerosols must be respirable, that is, have a mean aerodynamic diameter of less than 5 xm, to ensure that a reasonable proportion will penetrate the respiratory tract defence systems of the nasal passages and the mucociliary clearance mechanisms. 

The respiratory tract is protected by a number of defence mechanisms, including ... 

From a drug delivery perspective, the components of the host defence system comprise barriers that must be overcome to ensure efficient drug deposition as well as retention in and absorption from the respiratory tract. Important non-absorptive clearance mechanisms include mucociliary clearance, alveolar macrophages and metabolism (Figure 6.2). 

Modulation of epithelial cell-bacteria interaction through EPs 7630 may protect mucous membranes from microorganisms evading host defence mechanisms. This provides a rationale for the treatment of upper respiratory tract infections with EPs 7630 (727). 

---