ABSTRACT
Liposomes can encapsulate drugs with hydrophilic and hydrophobic properties, which can be entrapped in the liposomes’ lipid bilayer interface and provide various therapeutic applications. Long-circulating liposomes can entrap hydrophilic long-chain polymers; due to the reduction in recognition of liposomes by opsonins to the reticuloendothelial system (RES), they possess a greater half-life in systemic circulation and exhibit target-specific delivery. The liposomes used in passive drug delivery are coated by polyethylene glycol, which resists the interaction of blood components with them, which causes them to escape from RES. The liposome makes contact with the cell membrane, where it is adsorbed onto the surface. There are certain factors to be considered during the formulation of liposome that will influence in vivo characteristics such as stability, drug characteristics, bilayer fluidity, bio-distribution patterns, size, and surface hydration. The fraction of drug cleared by RES is influenced by the size of liposomes.
