Hej. Hofland et al., ESTRADIOL PERMEATION FROM NONIONIC SURFACTANT VESICLES THROUGH HUMAN STRATUM-CORNEUM IN-VITRO, Pharmaceutical research, 11(5), 1994, pp. 659-664
The permeation of estradiol from vesicular formulations through human
stratum corneum was studied in vitro. The vesicles were composed of no
nionic n-alkyl polyoxyethylene ether surfactants (C(n)EO(m)). The ther
modynamic activity of estradiol present in each formulation was kept c
onstant by saturating all formulations with estradiol. The effects of
both the particle size and the composition of the formulation on estra
diol permeation across excised human stratum corneum were investigated
. Stratum corneum that was pretreated with empty surfactant carriers a
llowed for significantly higher estradiol fluxes compared with untreat
ed stratum corneum. However, estradiol fluxes obtained in these pretre
atment experiments appeared to be significantly lower than those obtai
ned by the direct application of the estradiol-saturated carrier formu
lation on top of the stratum corneum. Furthermore, in the case of pret
reatment of the stratum corneum, an increase in carrier size resulted
in a decrease in estradiol flux. For direct application the opposite w
as found. Two mechanisms are proposed to play an important role in ves
icle-skin interactions, i.e., the penetration enhancing effect of surf
actant molecules and the effect of the vesicular structures that are m
ost likely caused by adsorption of the vesicles at the stratum corneum
-suspension interface.