Targeting to macrophages: role of physicochemical properties of particulate carriers--liposomes and microspheres--on the phagocytosis by macrophages.

Heterogeneous functions of macrophages in human immune systems have renewed interest in targeting of drugs to these cells. Various carrier systems have emerged to deliver drugs to macrophages, albeit the efficacy, reliability and selectivity of these carriers are still in question. To date, the most extensively studied carriers are liposomes and microspheres. Various physicochemical properties of these carriers can alter their efficacy and specificity to a great extent. These properties include hydrophilicity, surface charge, composition, concentration, and presence of various ligands. In this review, a comprehensive evaluation of the literature has been carried out in order to show the role of these parameters in the design of carriers for targeting of drugs to macrophages.