Introduction - Lipid Nanoparticles: Production, Characterization and Stability - page 4

Table 1.1 Advantages of using a solid lipid in the manufacture of colloidal drug carriers
Solid core
Enhanced physicochemical stability of colloidal carrier
Enhanced chemical stability of encapsulated drug molecules
Reduced mobility of drug molecules
Enhanced mechanical stability
Increase in electrochemical stability due to reduction in diffusing drug molecules (which otherwise
decrease stability)
Prevention of drug leakage
Sustained-release of drugs
Static emulsifier-particle interface
Facilitates surface modification
Facilitates drug targeting
1.3 Lipid Nanoparticles: History and Scope
Speiser and co-workers were among the first to use solid lipids in the preparation of
nanopellets. They used high sheer homogenizers followed by ultrasonication to pro-
duce lipid nanopellets for peroral administration (Speiser 1986 ). Lipospheres, which
are carrier systems similar to nanopellets, were later produced by Domb ( 1993 ). The
use of lipid nanoparticles as drug carriers has been greatly exploited ever since (e.g.
Cutanova Cream nano Repair Q10, NanoLipid Restore CLR, IOPE SuperVital, etc.).
1.4 Lipid Nanoparticles: Types
1.4.1 Solid Lipid Nanoparticle (SLN)
Solid lipid nanoparticles (SLNs) are often referred to as the first generation of
lipid nanoparticles. Gasco ( 1993 ) and Müller and Lucks ( 1996 ), for example, pre-
pared SLNs using different production techniques, and the number of research
groups actively involved in SLN production has increased rapidly in subsequent
years. SLNs have roused increasing attention in the scientific community as prom-
ising drug carriers due to their simplicity and versatility. By definition, they have
small particle sizes and, in fact, the smaller the particle size the more likely they
are to remain stable, the more likely they are to exhibit targeted responses, and the
more likely they are to encapsulate large amounts of drugs (Müller et al. 2002 ;
Wissing et al. 2004 ). The challenge, with SLN production, is to produce a small
particle size but without generating a polydisperse sample.
SLNs are colloidal particles derived from oil-in-water emulsions by replac-
ing liquid lipids with a lipid matrix that is solid at body temperature and stabi-
lized by the use of surfactants. A schematic diagram depicting an SLN is shown in
Fig. 1.1 a. SLNs potentially emphasise the benefits of colloidal carriers discussed
earlier (see Sect. 1.2 ) whilst reducing the probable shortcomings associated with