ABSTRACT
The human respiratory tract has the potential to provide the means for non-invasive drug delivery of molecules that could not be efficiently and reproducibly, or rapidly, delivered without injecting them into the body. From the early parts of the twentieth century, there have been many attempts to use inhalation to deliver insulin for the treatment of diabetes. Satisfactory efficiency of delivery is only meaningful when it goes hand-in-hand with adequate safety. The inhalation route in general has been associated with a very good safety record for the delivery of asthma drugs evidenced both during the development stages and by their wide acceptance post-approval. The gas-exchange areas, for example, do not have the mucociliary clearance but they have alveolar macrophages that can phagocytose ‘‘foreign’’ materials. These alveolated regions also have a much greater and more permeable environment than the upper and conducting airways.
