Physicochemical Stability - Lipid Nanoparticles: Production, Characterization and Stability - page 91

aggregation in freeze-dried lipid nanoparticles (Zimmermann et al. 2000 ). Other
sugars such as mannitol, sucrose, fructose, glucose and sorbitol have also been used.
An alternative method for elimination of water involves converting a liquid dis-
persion into a dry powder by a process called “spray drying”. The shear forces
involved in the process may destabilize the system. Exposure of the sample to the
elevated temperatures for drying is very short; the thermal stress on the material is
dramatically reduced due to the latent heat of vaporization. There is always a risk,
however, of melting of lipids which can alter the particle size of the nanoparticles
(Blasi et al. 2013 ).
5.6 Conclusions
Physicochemical stability is an important consideration in the development of
lipid nanoparticle formulations. The stability assessment of lipid nanoparticle for-
mulations involves multi-technique investigations. The first major step in the quest
to achieve desired physicochemical stability is the appropriate selection of formu-
lation ingredients. The composition of formulations has an implied influence on
various parameters, including particle size, zeta potential, drug encapsulation effi-
ciency, loading capacity, crystallinity and drug release.
Finally, it should be acknowledged that the desired formulation stability is
always a compromise between storage stability (shelf-life) and the destabiliza-
tion mechanism that modulates the release of drug in biological systems. The goal,
then, is not necessarily to create the most stable dispersion.
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