Lipid-based dispersions for drug delivery

In this chapter, the use of lipid-based dispersions in pharmaceutics is described. In particular, solid lipid nanoparticles (SLNs), ethosomes, and cubosomes are presented as innovative carrier systems alternative to liposomes. SLNs are liquid dispersions of nanoparticles that have attracted increasing attention in recent years and are regarded as an alternative carrier system to traditional colloidal systems, such as emulsions, liposomes, and polymeric microparticles and nanoparticles. The soft structure of ethosomes allows facilitated delivery of the incorporated molecule into the skin lipid bilayers. Particularly, the major potential of ethosomes in promoting penetration through skin with respect to liposomes is ascribed to an interaction between ethosomes and skin lipids. Cubic liquid crystalline materials are an active research topic because their unique structure lends itself well to controlled release and skin care applications. Cubosomes usually have been produced by means of time-consuming methods involving high energy input. Conversely, we have recently tested more conventional dispersion techniques demonstrating that the emulsification of monoglyceride/surfactant mixtures in water results in the formation of aqueous dispersions composed of large lipid particles (28% w/w) and cubosomes characterized by spheroidal shape, few aggregates, mean diameter of 193.5 nm, and high percentage of recovery (88% wt/wt). Organoleptic and morphological features of cubosomes do not change by time, appearing free from phase-separation phenomena for almost 1 year from production. Photon correlation spectroscopy studies showed that cubosomes undergo an initial increase in mean diameter within the first month following production; afterwards they generally maintain their dimensions for the next 6 months.