Physical stability of the aqueous NLC is the absence of particles
aggregation and creaming in the formulation of cosmetic and pharmaceutical
products. NLC should be small size in the nanometer range. The particles are kept in
suspension by the Brownian motion of the water molecules. NLC surface electrical
charge, the particles are stabilized by electrostatics repulsion, and the physical
stability is even further enhanced when sterictically stabilizing polymers. Han et al.
(62) were studies the influence of surfactants on properties of NLC. The formulation
in the study combined four types of additives including ionic surfactant (sodium
deoxycholate), non-ionic emulsifier (Poloxamer 188 and Tween-80), and Lecithin to
obtain favorably stable NLC drug delivery system, which could stabilize for more
than 1 year without phase separation at 4°C. Teeranachaideekul et al. (10) studies on