Liposomes as Targeted Drug‐Delivery Systems

The term “liposomes” was given by Weismann and coworkers to the spontaneously formed closed structures of phospholipid bilayers, when they were hydrated in water. Gregoriadis established the concept that the drugs could be encapsulated into liposomes and used as drug-delivery vehicles. The manufacturing of liposomes has advanced significantly, beginning with the thin lipid film hydration and progressing through reverse-phase evaporation, freeze-drying and scalable ethanol injection methods. Stealth technology has been extensively investigated in developing a drug-delivery system making these liposomes difficult to detect by the mononuclear phagocyte system. Liposome-based products are complex formulations; hence, small changes in the formulation may significantly affect the clinical outcomes. Targeted drug delivery is a strategy that preferentially and selectively delivers the active therapeutics to the site of action, that is, target site while concurrently minimizing the access and exposure to the nontarget site.