S. Zhong, F. Olechowski, R. M. Müller, S. M. Pyo
Dermal active substances, in particular anti-aging ingredients, find frequent use in cosmetics for their beneficial effects on theDermal active substances, in particular anti-aging ingredients, find frequent use in cosmetics for their beneficial effects on theskin. But they can only have these effects if they are bioavailable. That means that the substance must efficiently penetratethe skin in a meaningful and effective concentration. Furthermore, the substance must be protected from degradation due toexternal influences such as light or oxygen, both as a raw material and in formulation. Retinol is a highly effective antioxidantand has long been known as an anti-aging ingredient. However, its chemical instability makes it a challenge for formulators.Furthermore, in high concentrations retinol causes skin irritation and redness. Retinol can be stabilised to a substantial degreeby embedding it in a semi-crystalline, unordered matrix of selected solid and liquid lipids in the form of submicron particles in anaqueous suspension. This also gives efficient, controlled penetration of retinol from the particles into the skin over a prolongedperiod, minimising skin irritation. At the same time, with their effective adhesion to the skin, the lipid particles help restore thedamaged skin barrier. This adhesive property also has the benefit of extending the release of retinol. The particles are in solidstate at skin temperature and they are stabilised in suspension.