Liposomes as alternative vehicles for sun filter formulations.

The aim of our study was to determine the influence of several types of liposomes with a different lipid composition on the percutaneous absorption of one conventional sun filter with a lipophilic character (ethyl hexyl methoxycinnamate) using both in vitro and in vivo methodologies. Three different liposomes were prepared with unsaturated and saturated phosphatidylcholine (PC, HPC), and with a wool lipid mixture (IWL) with a composition similar to that of the stratum corneum lipids. Results showed that the liquid crystalline state associated with PC liposomes plays a key role in enhancing skin penetration. when liposomes with a composition and structural organization similar to that of the stratum corneum lipids (HPC and IWL) are used, the skin penetration is retarded, suggesting a certain reinforcement of the stratum corneum barrier. These two types of liposomes could be regarded as alternatives to conventional oil/water emulsions in the formulations of lipidic sun filters. Finally, an acceptable correlation was obtained using both in vitro and in vivo methodologies to evaluate the corresponding skin absorption profile.