Liposome-Based Drug Delivery—A New Therapeutic Paradigm

Abstract

Targeted drug delivery systems have evolved over the years to improve the therapeutic efficacy of drugs and reduce their side effects. In this context, a range of nanoscale delivery vehicles like liposomes have been developed. Liposomes are spherical particles made up of phospholipids, fatty acid esters, and fat alcohol ethers of phosphatides. They consist of a hydrophilic core and an amphipathic outer lipid bilayer. The advantages of using liposomes for drug delivery include biocompability, feasibility to deliver hydrophilic and hydrophobic drugs, low toxicity and wrapping lipids around inorganic and polymeric nanoparticles to form supported monolayers or bilayers for enhanced permeability and retention effect. Different methods of synthesis of liposomes have been developed over the years and they are based on a common principle of hydration of lipids dissolved in organic solvents. The various properties that play a decisive role in efficient drug delivery from liposomes include size, charge and fluidity of liposomes. The mechanism of drug delivery by liposomes involves either fusion of the liposome with cell membrane or by ingestion and degradation of liposomes inside the cell that leads to release of the loaded drug into the cell. Further, liposomes can be efficiently targeted by specific ligand binding. The current chapter discusses the rationale of liposome synthesis, advances in the synthesis process, current state-of-art of liposome drug delivery systems for therapeutic applications in treatment of microbial diseases and cancer, and regulations related to commercialisation of liposomes with examples like DOXIL and MYOCET.