Figure 3 shows the variation of TEWL before the application of the formulations and 5 min, 2 and 4 h after its removal (application time was 1 h). It is well known that corticosteroids increase the TEWL value as a signal of the disturbance of skin barrier function . However, for all tested formulations TEWL did increase in a non-significant way when measured 5 min post-application, then decreased gradually to reach the basal value after 4 h. The reason for the increase of TEWL after formulation removal is probably the evaporation of residues of water contained in the formulation. Overall, at least for the application time examined in this study, the commercial cream, NP and Na-DOC gel formulation produced no significant disturbance on the barrier function of stratum corneum after a single application.