In vivo and in vitro evaluation of topical formulations containing physiological lipid mixture for replacement of skin barrier function

Abstract

Aim: The aim of the study was to describe a new in vivo and in vitro approach of the efficacy evaluation of cosmetic emollients to better understand the link between the formulation and the activity of cosmetic products.

Methods: Two long term in vivo studies were carried out on nine healthy Caucasian volunteers mean age 40±12 years to evaluate the protecting and repairing effects of the two different barrier repair cosmetic formulations. The application of the formulations was repeated once a day during 7 days and biophysical parameters (TEWL and Skin Hydration) were measured before and after Sodium laureth sulphate exposure The in vitro study was carried out by freeze substitution transmission electron microscopy (FSTEM) on stratum corneum samples obtained by sections of fresh skin from young pigs, depleted with a solvent mixture and treated with the two products

Results: The in vivo results demonstrated that daily product application provided a reinforcement of the skin barrier with protecting and repairing effects from chemical injuries the extent of which was dependent on the formulation features (product A>product B) The role of the technical form on the lipid availability was confirmed by the in vitro evaluation tests.

Conclusion: The results point out that a daily application of physiological lipid mixture containing emulsion can protect healthy skin and promote the reparing effect on unpaired barrier skin, reducing TEWL and maintaining hydration of the stratum corneum. The efficacy degree is higher when the cosmetic form promotes the availability of active ingredients increasing the product performance.