Macromolecular carriers passive targeting

In cancer treatment, passive targeting of macromolecular carriers to tumors is a commonly used approach. This passive targeting is based on the enhanced permeability and retention (EPR) effect, which leads to an accumulation of the high molecular weight carrier in the tumor tissue. The EPR effect arises from the different physiology of tumor vasculature, where the vessel walls are highly porous and lack the tight junctions that are present in healthy tissue. As a result, macromolecular carriers extravasate and accumulate preferentially in tumor tissue relative to normal tissues [63, 64]. 

Grayson, S.M. and Godbey, W.T. (2008) The role of macromolecular architecture in passively targeted polymeric carriers for drug and gene delivery. Journal of Drug Targeting, 16,329-356. 

Fig. 3.6 Targeting strategies for cancer therapy. (1) Passive targeting can be achieved by enhanced permeation and retention (EPR) effect mediated by leaky vascular structures. Accumulation of macromolecular drugs or nanoparticles increases local drug concentration by degradation of drug carriers at the extracellular space or inside cells after endocytosis.

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