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Fig. 4 | AAPS Open

Fig. 4

From: Scope and relevance of a pulmonary biopharmaceutical classification system AAPS/FDA/USP Workshop March 16-17th, 2015 in Baltimore, MD

Fig. 4

Transport pathways for drugs across an epithelial barrier (Kolaca et al. 1996). (1) passive transcellular diffusion (probably for most small, sufficiently lipophilic molecules), (2.) paracellular diffusion (for hydrophilic molecules and depending on the integrity of intercellular junctions, also a pathway for peptides and proteins) (3) active transport via specific receptors and “pumps” (4) vesicular transport (endo-transcytosis) (5) efflux to the apical side and/or metabolism by epithelial cells

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