The use of penetration enhancer adjuvants was emerged as a growing trend in
transdermal drug delivery. These adjuvants may reduce the capacity for drug binding to skin
and promote the permeation of bimolecules through the skin. The main objective of this study
was to evaluate the effect of polyvinylpyrrolidone (PVP) and hydroxypropyl–beta-cyclodextrin
(HP- -CD) as well as certain chemical enhancers on solubility of unlabeled corticosterone
(CS) and its transdermal permeation through skin. The results revealed that autoclaving CS
with PVP maintained supersaturated state through inhibition of crystal growth and in turn
increased its flux across hairless mouse skin. The data showed also that HP- -CD had no effect
on CS permeation but could be used as solubilizing agent for highly lipophilic skin permeation
enhancers octyl pyrrolidone (OP) and dodecyl pyrrolidone (DDP). It also prevented depletion
of such lipophilic enhancers into skin, increased by this way the permeation enhancement of
these adjuvants