Hydrotalcite: a smart technology for innovative active ingredients
Clays are commonly used in the cosmetic and pharmaceutical industries, either as ingredients or as active ingredients. Hydrotalcites are a special class of biocompatible clays able to host in the interlayer region a wide range of active ingredients. The intercalation of cosmetic actives into the layered structure of the hydrotalcite allows the preparation of new raw materials with enhanced stability towards oxidation and photodegradation, better local bioavailability and easier workability. Intercalation compounds have been tested to improve the solubility and kinetic of release of poorly-soluble ingredients. Release studies on ZnAl_SAL showed that the hydrotalcite technology can be successfully applied to prepare dermo-cosmetic formulations with controlled release and high bioavailability of actives.
Great attention has been focused on clay minerals since the earliest days of civilization due to their abundance in nature and potentials. The use of clay minerals for curative and protective purpose is as old as mankind itself (1). The first recorded use of medicinal clay is on Mesopotamian clay tablets around 2500 B.C. Also, ancient Egyptians used clay as anti-inflammatory agents and antiseptics. Clays have been widely employed in medicine and properly administered clays can purify the blood, reduce or even eliminate infection, heal ulcers, and even rid the body of certain allergies. Cutaneous therapy based on clay minerals for the treatments of seborrhoeic skin as antimicrobial and antifungal agents has also been developed (2). Clay minerals possess excellent properties such as low or null toxicity, good biocompatibility, and promise for controlled release, thus give rise to the interest to their development for biological purposes, for example, in the pharmaceutical and cosmetic fields. Studies on both natural and synthetic clay minerals including hydrotalcites for biological applications are extensively carried out (3).