Fig. 5From: Scope and relevance of a pulmonary biopharmaceutical classification system AAPS/FDA/USP Workshop March 16-17th, 2015 in Baltimore, MDA schematic diagram of the two compartment “Tube and Bucket” model of lung clearance and absorption. The central airways experience clearance and absorption, the peripheral lung only experiences absorption. (As suggested by Hastedt 2014)Back to article page