Background: Semisolid SLNs are novel strategy for dermal drug administration instead of
incorporating the SLN dispersions into conventional semisolids. Etofenamate loaded semisolid SLNs
were successfully prepared and in vitro characterization of formulations were performed in our previous
study. The present study is an attempt to evaluate the dermal behavior of the semisolid SLNs selected
on the basis of previous research and investigate the properties in terms of the convenience for topical
Objective: The objective of this study is to evaluate the skin penetration characteristics of semisolid
SLN formulations. The occlusive and mechanical properties of semisolid SLNs were also evaluated because
of their impression on the dermal behavior of the formulations.
Method: The occlusive properties were investigated by in vitro occlusion test. Texture analysis was performed
to define the hardness, compressibility, adhesiveness, cohesiveness and elasticity of the formulations.
Rat skin was chosen to evaluate the ex vivo penetration of etofenamate loaded semisolid SLNs
and commercial gel product. Coumarin-6 was used to visualize the dermal distribution of the semisolid
SLN formulations. For monitorizing the penetration of coumarin-6 into the skin samples Confocal Laser
Scanning Microscopy was employed.
Results: The occlusive and mechanical properties of C1 coded semisolid SLN formulation were found
more favorable in comparison with P1. The cumulative etofenamate amount in skin samples was found
to be 39.88 ± 1.50 μg/cm2 for C1 and 30.56 ± 2.10 μg/cm2 for P1 coded formulations. According to
CLSM images, greater fluorescence intensities and deeper skin penetrations were obtained with both of
the semisolid SLNs in comparison to plain Carbopol gel.
Conclusion: It can be concluded that the semisolid SLNs are promising alternative dermal drug delivery
systems to the conventional dosage forms.