Table 2. Comparison of technologies employed for SLN/NLC preparation^78-82 .

Lipid Nanoparticle Technology	Methodology	Advantage	Disadvantage
High pressure Homogenization	Hot Homogenization Drug incorporated lipid melt dispersed in surfactant rich hot aqueous phase, followed by homogenization under high pressure.	• Bulk manufacturing • High stability and loading of drugs.	• Not recommended for thermolabile drugs. • Drug may enter in aqueous medium under homogenization
	Cold Homogenization Drug dissolved in melted lipid, swiftly cooled under liquid nitrogen/dry ice, followed by milling. Then milled powder disperse in surfactant rich aqueous solution, followed by homogenization under high pressure.	• No drug partition in aqueous phase. • Thermolabile drugs can also be incorporated	• Surfactant involved may cause irritation/sensitization.
Solvent emulsification/evaporation	Lipid dissolved in organic solvent immiscible with water, followed by formation of an emulsion stabilized by surfactant. Solvent removal by solvent removal under reduced pressure.	• No thermal stress.	• Organic solvent used for dissolving lipid may possess toxicity. • Varied particle size of nanoparticles.
Super critical fluid technology	Supercritical fluids like carbon dioxide have been used for solvent extraction through o/w emulsions.	• Carbon-dioxide can serve as an alternative to other toxic organic solvents.	• Majority of organic solvents utilized are hazardous. • Large quantity of surfactant concentration required.
Ultrasonification	Lipid phase is dispersed surfactant rich aqueous phase, followed by homogenization under high shear/ultrasonication	• Simple manufacturing process.	• Polydispersed nanoparticles. • High concentration of surfactant.
Spray drying	SLN can be prepared from aqueous dispersion.	• Cost effective and substitute to lyophilization.	• Particles aggregation. • Lipids with melting point above 70° C can only be used