To further clarify the previous concepts,
an uptake study was conducted (ElMaghraby et al., 1999) in which stratum corneum membranes were dipped into the test formulation or aqueous solution for a short time (10 min).
Drug uptake was increased only from medicated carriers indicating the necessity of coapplication of drug with the nano-structures.
The uptake ratios (URs) between the vesicles and solution ranged from 23 to 29 with no significant differences between individual formulations.
This significant uptake after such a short timemay imply high affinity of the vesicles for the stratum corneum.
Considering the superiority of deformable nano-aggregates over traditional liposomes in increasing transepidermal flux,
and that no significant differences were found in the URs at short contact time, these finding suggest that ultradeformable
vesicles could have promoted diffusion through the membrane rather than partitioning (uptake) into the tissue.