Fate of liposomes and encapsulated drug after intravenous administration i.v.injection of liposomes Uptake RES/MPS Liposome disintegration in Long circulating liposomes blood (SSL) Release in cell Slow release of agent in blood,and/or:accumulation Release of(in)active Release in blood at non-MPS tumor and agent from cell inflammation sites Reticuloendothelial system=RES Mononuclear phagocyte system=MPS Proposed Liposome Classification Based on Pharmacologic Behavior ·Vehicle -Majority of drug rapidly released into central compartment prior to MPS uptake of liposome -Possible safety advantages over other vehicles (i.e.,cremophor/ethanol,Tween)>less hemolysis,allergic reactions -Infusion reactions to liposomes well documented,so safety trade-off uncertain7 Fate of liposomes and encapsulated drug after intravenous administration Reticuloendothelial system = RES Mononuclear phagocyte system = MPS i.v. injection of liposomes Uptake RES/MPS Liposome disintegration in blood Long circulating liposomes (SSL) Release in cell Release of (in)active agent from cell Release in blood Slow release of agent in blood, and/or: accumulation at non-MPS tumor and inflammation sites