SLN was higher than that in NLC.29) No intact SLN and NLC
penetrated into the skin,31) therefore ATRA might be released
from the nanoparticle the drug with or without permeation
enhancers permeate through the skin. After application of
the lipid nanoparticles onto the skin, film formation occurs,
which subsequently leads to an occlusive effect. This leads to
reduced water loss, resulting in increased skin hydration, and
consequently, enhances the penetration of the drug into the
skin.30) Therefore, it is anticipated that the formulation containing
a greater amount of solid lipid would lead to greater
skin penetration.
To make correlative conclusions regarding the skin targeting
of lipid nanoparticles, distributions of rhodamine b base
in porcine skin was investigated using CLSM. It is believed
that rhodamine b base (a lipophilic compound) appears in the
inner phase of lipid nanoparticles (the lipid phase). Figure 5
illustrates the results obtained from CLSM following dermal
delivery of rhodamine B base via the skin for 8 h from rhodamine
B base in M (control) (5a), rhodamine B base loaded
10% L-SLN (5b), rhodamine B base loaded 10% L-NLC (5c),
and rhodamine B base loaded 10% L-NE (5d). The skin thickness
was optically scanned at ca. 10 µm increments from the
surface of the skin (left to right, top to bottom). Ten percent
L-SLN showed the highest intensity of fluorescence, followed
by 10% L-NLC, 10% L-NE and dye in M, respectively (Fig.
6). The fluorescence intensity in the horizontal section at 30
to 75 µm of 10% L-SLN and 10% L-NLC was very strong and
gradually decreased with increasing depth.
Rhodamine B base was used as a model lipophilic drug
for studying skin distribution by CLSM because it has low
solubility and is a fluorescent molecule. The skin distribution
results for rhodamine B base loaded terpene composited lipid