Long circulating microparticulate drug carriers

To exert its activity a drug must reach its pharmacological site(s) of action(s) within the body. One of the current approaches to achieve site specific delivery utilises the use of a carrier. This review focuses on the physicochemical and biological properties of polymeric particulate carriers in the nanometre size range surface modified by poly(ethylene oxide) (PEO). Such systems are able to bypass the normal physiological defence processes occurring after the intravenous injection of particulates and, depending on the particle size and PEO layer properties, remain for a prolonged period of time in the systemic circulation, or have a degree of selectivity for sites of deposition within the body.