Multiple W/O/W emulsions as dermal peptide delivery systems

Dermal delivery of peptides is a difficult task that needs to be solved by formulators in the pharmaceutical as well as in the cosmetic industry. Since multiple W/O/W emulsions are interesting vehicles for delivery of peptides, the influences of different plant-derived oils, namely avocado, wheatgerm and olive oil, on the formation and properties of multiple emulsions were investigated. The multiple W/O/W emulsions were characterized in terms of long-term stability, rheological properties, droplet size and internal structure. Moreover, the in vitro skin permeation of acetyl hexapeptide-8 (AH-8) from the multiple emulsions was investigated by Franz-type diffusion cells with porcine skin. The use of olive oil led to the most stable multiple emulsion with enhanced skin permeation of AH-8 compared to the other multiple emulsions. Moreover, a significantly increased skin permeation of AH-8 at acidic compared to physiological conditions revealed a strong dependency of AH-8 permeation on the chosen pH value.