
408 CHAPTER 15 Some approaches to large-scale manufacturing of liposomes
15.4.3 FREEZE-DRYING METHOD
Since phospholipids are unstable in aqueous dispersions, freeze-drying can be used
as a method to stabilize liposomes for long-term storage [39,40]. Freeze-drying, also
called lyophilization, relies on freezing the liposome dispersion followed by removal
of water under very low pressure (below the triple point of the system). However,
freeze-drying itself may exert a destabilizing effect on liposome bilayers, leading to
liposome fusion and leakage of entrapped hydrophilic material during lyophilization
[40]. This may be minimized by the addition ...