Polymers for targeted and/or sustained drug delivery

Recent advances in the use of polymers for passive targeting of drugs attached or incorporated into polymeric species (enhanced permeability and retention, EPR) as well as active targeting of drugs by ligands or antibodies of receptors overexpressed on the surface of the targeted cells, is discussed in the present review. Examples of sustained, slow release of a drug incorporated into a polymeric matrix are cited. Drugs used for passive modes of targeting have been described in the context of polymer-drug conjugates, drugs in the polymer coated liposomes, and drugs inserted into polymeric micelles. Active targeting of the drugs and their internalization by receptors, on the surface of the targeted cells, was also discussed. Release of the drugs inside cells, after are broken the environmentally sensitive links attaching them to polymeric platforms was described. Examples illustrate targeting drug by local heat generated by ultrasound, or by photodynamic treatment. Delivery modes of drugs incorporated into other nanoparticles and the concept of prodrugs have been investigated. Copyright © 2008 John Wiley & Sons, Ltd.