Direct evidence for bioconversion of vitamin E acetate into vitamin E: an ex vivo study in viable human skin.

For better stability, vitamin E is commonly used as the non-active esterified pro-drug. Such esters are postulated to be hydrolyzed to the free active form by skin-related esterases. So far, successful conversion of esterified vitamin E to free vitamin E (tocopherol) has been mainly delineated from observed biological effects. Quantitative evidence in human skin is poor. In vitro and in vivo studies on human and animal skin have proved ambiguous. Formulation-based effects may have added to this controversy. In the present study, comparable amounts of vitamin E acetate (i) in oil (Mygliol-812N), (ii) surfactant-solubilized in water, (iii) encapsulated in liposomes, or (iv) encapsulated in Nanotopes were applied to human skin mounted in modified Franz-perfusion chambers that permit emulation of both open or occlusive conditions. The distribution of vitamin E(total) (vitamin E acetate + vitamin E) was assessed on the skin surface, in the horny layers, and in the underlying skin by high-pressure liquid chromatography (HPLC), with a recovery higher than 90%. Vitamin E acetate in Mygliol deposited exclusively on the surface and in the stratum corneum. In contrast, solubilized or encapsulated vitamin E acetate deposited also in the underlying skin. Nanotopes performed best, followed by liposomes and solubilized vitamin E acetate. Non-occlusive application favored deposition in the skin relative to occlusive application. Conversion of vitamin E acetate to vitamin E was not observed on the skin surface or in the horny layers, while in the underlying skin up to 50% of the vitamin E(total) was deacetylated.

The effectiveness of molecular oxygen in cosmetic formulations.

Synopsis In a preliminary clinical study, two cosmetic preparations were compared, one without an oxygen carrier and therefore without oxygen, the other one containing the oxygen carrier, fully saturated with oxygen. The parameters measured were the moisture content of the skin and the skin profile. Since the oxygen-free product contained the same ingredients, including phospholipids in liposomal form, with the exception of perfluorodecalin - the oxygen carrier, this investigation showed that perfluorodecalin plus molecular oxygen improves the barrier function of the skin. In a second clinical study, five cosmetic preparations containing various amounts of molecular oxygen from 1.44 ml to 4.5 ml per 100 ml product were compared. The parameters measured were the oxygen partial pressure of the skin, the moisture content of the skin, and the skin profile. A linear dose-dependent increase in oxygen partial pressure of the skin (r=0.978) and a linear dose-dependent reduction in fine lines and wrinkles (r=0.9855) was found. The results for the increase in skin moisture were more difficult to interpret. There seemed to be an overlap of the moisturizing base with the efficacy coming from the increasing amount of oxygen per application.

Liposomes from soya phospholipids as percutaneous drug carriers. 1st communication: qualitative in vivo investigations with antibody-loaded liposomes.

The penetration behaviour of liposome (prepared from NAT 106)-incorporated proteins was investigated in vivo by use of monoclonal antibodies (MOAB) as model substances on the skin of young pigs. Within 20 min of topical application, an even distribution of liposome-incorporated antibodies through all skin layers could be shown by means of an immunohistochemical stain.

Liposomes from soya phospholipids as percutaneous drug carriers. 2nd communication: quantitative in vivo investigations with radioactively labelled liposomes.

The percutaneous absorption of liposomes (prepared from NAT 106) was investigated with radioactively labelled substances in comparison with percutaneous absorption without liposomes (controls) in vivo on the skin of young pigs. Radioactivity was monitored as a function of time in skin tissue, plasma or blood and in urine. Elevated tissue levels, increased absorption and renal elimination of the various liposomal preparations in comparison to the controls were measured.