Table 2.

Summary of liposome preparation methods and their suitability for continuous manufacturing Reprinted/adapted with permission from [117] and used under the Creative Commons license permission (CC BY 4.0). Copyright 2018, John Wiley & Sons, Inc. All rights reserved.

Method	Mechanism	Suitability for Continuous Manufacturing
Bangham	Rehydration of thin lipid film	Not practical—needs continuous dehydration/rehydration steps
Sonication	Sonication of aqueous lipid suspensions	Requires small-scale batch operation to ensure sonication efficiency
Reverse-phase evaporation	Aqueous phase added to organic phase and evaporated to form liposomes	Very complex to regulate continuous solvent evaporation, sterile boundary hard to establish
Detergent depletion	Liposomes forms through detergent–lipid interaction	Slow process with difficult-to-establish sterile boundary, detergent use generally disadvantageous
Microfluidic channel	Intersection of lipid and API solutions in micromixers	Continuous but small/medium scale that can be upscaled in parallel
High-pressure homogenization	Liposome formation through high-pressure mixing	Very high pressures required, difficulty in sterilizing equipment
Heating	Heating of lipid aqueous/glycerol solution to form liposomes	Hydration step and high temperatures make continuous production impractical
Supercritical fluid methods	Use of supercritical fluids as solvent for lipids instead	High pressures required for feed vessels make resupply/continuous operation impractical
Dense gas	Use of dense gas as solvent for lipids	High pressures required for feed vessels make resupply/continuous operation impractical
Dual asymmetric centrifugation	Mechanical turbulence and cavitation	Only for batch sizes ~1 g or less
Ethanol/ether injection	Precipitation of liposome from organic phase into aqueous	Simple process with inherently continuous liposome formation step
Crossflow	In-line precipitation of liposome from organic phase into aqueous	Simple process with inherently continuous liposome formation step