Fig. 2.

Advantages of the inhalation route. The nanoparticle inhalation route has many advantages inherent in the physiology of the respiratory system: (1) avoids the first-pass metabolism effect as well as gastrointestinal proteolysis; (2) enables direct action on injured tissue; (3) makes it easier to reach the circulatory system because of the presence of the dense capillary network and its thin interface, contributing to lower drug doses