Abstract

Efficient dermal delivery of actives being poorly soluble in water and simultaneously in oils is a challenge in consumer care and cosmetics. A universal technology to increase the bioactivity is submicron crystals, i.e. smartCrystals (> 100 nm to < 1,000 nm) and nanocrystals (≤ 100 nm). The size reduction below 1 µm increases the saturation solubility, thus diffusion pressure into the skin. Incorporation into dermal formulations can be done simply by admixing of smartCrystal concentrates, being commercially available, e.g. various anti-oxidants. The efficiency is documented by in vitro and in vivo data (bioactivity increase in humans up to factor 1,000). The technology allows the use of new classes of plant molecules, being not active before.

INTRODUCTION

Delivery problems in dermal application
Poorly soluble plant actives such as resveratrol, rutin, apigenin etc. are of high interest for delivery to the skin, but their penetration into the skin is very low, therefore they have no sufficient dermal “bioactivity”. The problem is that these molecules are poorly soluble in water and simultaneously in oils. Therefore – in contrast to e.g. coenzyme Q10 – they cannot be dissolved in the oil phase of dermal creams. Application of a suspension of powdered active in a gel or the water phase of a lotion does not solve the problem. The saturation solubility cs is too low, this results in a very low concentration gradient between dermal formulation as “donor compartment” and the skin as “acceptor compartment” (Figure 1, upper). The present regulatory trend is requiring more and more proofs of dermal effects, to substantiate claims for a dermal product. Therefore it is not sufficient anymore just to admix an active to a product, it should be added in a technical form that it develops sufficient dermal bioactivity in the skin. Therefore smart delivery systems to mak ...