Transport of Biologics in the Body

The delivery of drugs to a target site frequently involves distribution and transport across various biological barriers. Factors that influence the transport of biologics include molecular size, membrane permeability, macromolecule binding and tissue uptake. The degree and nature of the impediment to drug flux will be addressed. Diffusive and convective mechanisms of drug transport are detailed. Lymphatic, vascular, endocytic and exocytic pathways of drug transport are highlighted.

Two primary transport mechanisms are discussed, diffusion and convection; specific drug transporters will be presented only as a backdrop. Three transport pathways are discussed, of which vascular route is largely for small molecules and oligopeptides. Lymphatic system, endocytosis and exocytosis are primarily for large molecule biologics. Finally, the factors that influence biologics distribution and transport are summarized, including molecular size, membrane permeability, macromolecule binging and tissue uptake.