In vitro and in vivo dermal absorption assessment of acetyl aspartic acid: a compartmental study.

Objective: The purpose of this study was to evaluate the dermal absorption of acetyl aspartic acid (A-A-A) through an in vitro and in vivo evaluation with human skin after 6 and 24 h of topical application of a cosmetic formulation containing A-A-A at 1%.

Methods: The in vitro experiment was carried out using the Franz diffusion cells system with ex vivo human skin samples. The profile of diffusion of A-A-A was evaluated after 6 and 24 h. The in vivo experiment was performed on human volunteers following a tape-stripping protocol after 6 h of topical application. A-A-A was quantified in the main skin compartments, that is the skin surface, the stratum corneum, the skin and the receptor fluid using LC-MS analysis.

Results: The 24-h in vitro experiment confirmed the great penetration potential of A-A-A in all skin compartments. After 6 h of topical application, the removed tape strips from both in vitro and in vivo experiments were analysed and the profile of diffusion of A-A-A was determined, allowing also an in vitro/in vivo comparison. The diffusion profile observed on the in vitro skin penetration test is highly representative of the in vivo situation evaluated on volunteers.

Conclusion: The combination of in vitro with in vivo data confirmed that A-A-A has the capacity to diffuse through the skin after topical application and reach the dermis as the targeted skin layer for potential anti-ageing benefits.