Table 1.

Methods for the preparation of SLNs and NLCs.

Methods		Advantages	Disadvantages
High energy methods	High pressure homogenization (hot homogenization and cold homogenization)	Widely used method for the preparation of SLNs and NLCs Hot method is used to heat stable materials whereas cold method is used for thermo-labile drugs	Polydisperse distributions and unproven scalability
	Microwave-assisted	This method is not frequently used	–
	Ultrasonication	Reduced shear stress and less time consuming	Contamination of metals may occur
	Supercritical fluid technique	No solvent is used as CO2 acts as a solvent Particles are obtained as dry powder	Very expensive method
Low energy methods	Microemulsion-based technique	No sophisticated machines are required for the preparation of microemulsion Less energy is required	Highly diluted dispersions of particles are obtained
	Double emulsion	Production of SLN-containing peptides and hydrophilic active ingredients	Particle growth will occur on storage
	Membrane contactor technique	Applicable for large-scale production	–
	Phase Inversion technique	Suitable for thermo-labile drugs	Tedious process
Organic solvent-based methods	Solvent emulsification-diffusion technique	Most used method for the preparation of the NLCs	Solvent may interact with the drug molecule
	Solvent emulsification-evaporation technique	Most used method for the preparation of SLNs	Solvent may interact with the drug molecule
	Solvent injection technique	Easy handling and fast production process	Solvent may interact with the drug molecule