Table 2.

Comparison between symmetric and asymmetric liposomes.

Item	Symmetric Liposomes	Asymmetric Liposomes
Compositions	Wide range of compositions and ratios	Need specific ratios and compositions Extra reagent or more than one preformed symmetric liposomes as template
Production methods and scalability	Established for production of different sizes and lamellarity Entrapment of small molecules and macromolecules (peptides and genes) For small scale (thin film hydration) and large scale (microfluidic technique) Good reproducibility in terms of characteristics and yields	Established for production of large unilamellar vesicles Nano-dimensions is emerging (e.g., pulse-jet flow) Successful entrapment with small molecules; potential for entrapment of large molecules with less chance of drug leakage and greater protection to labile drug More complex and with extra steps or reagents (for example, to enable lipid exchange) Custom made equipment/devices; scale up opportunity remains to be established
Characteristics, routes, and Stability	Prone to oxidation and hydrolysis related to lipid in use Good long term storage data Parenteral route is the main but can be adopted for all other routes Vesicles with targeting ability (versatile surface modifications)	Prone to lipid instability; potential interleaflet conversion Limited long-term stability data Targetable with different routes and better resembles to biological membranes
Physicochemical properties	size, shape, lamellarity, zeta potential and others.	Prove of asymmetry apart from standard tests.