Abstract

The global facial care market offers numerous opportunities for enhancing the outward appearance of the facial area. For this, formulators have numerous cosmetic active ingredients at their disposal. However, a powerful active ingredient can only achieve the desired effect on the skin if it has the relevant bioavailability. The active ingredient must, therefore, be able to penetrate the skin efficiently and build up a specific concentration of the active ingredient there.

Glabridin is a natural whitening agent extracted from the liquorice root (Glycyrrhiza glabra). It intervenes in the biosynthesis of the skin’s own pigment (melanin) and lightens the skin. Its efficacy has been confirmed in numerous publications. However, it is difficult to formulate this active ingredient as it has a very low solubility in lipids. If attempts to incorporate the active ingredient homogeneously into the facial care formulation do not succeed, it will not achieve the relevant bioavailability. This is not the desired outcome given the high price of the active ingredient (five figure amounts per kg). Efficient, controlled penetration of the skin by Glabridin can be achieved by embedding Glabridin in submicron particles made of a semi-crystalline, unordered matrix of selected liquid and solid lipids. Furthermore, the lipid particles help to repair a damaged skin barrier by adhering to the skin thanks to effective adhesion. This adhesion offers the added advantage of prolonged release. The particles are stabilised in suspension and remain in a solid state even at skin temperature.