Combination of argan oil and phospholipids for the development of an effective liposome-like formulation able to improve skin hydration and allantoin dermal delivery

Allantoin is traditionally employed in the treatment of skin ulcers and hypertrophic scars. In the present work, to improve its local deposition in the skin and deeper tissues, allantoin was incorporated in conventional liposomes and in new argan oil enriched liposomes. In both cases, obtained vesicles were unilamellar, as confirmed by cryo-TEM observation, but the addition of argan oil allowed a slight increase of the mean diameter (∼130 nm versus ∼85 nm). The formulations, especially those containing argan oil, favoured the allantoin accumulation in the skin, in particular in the dermis (∼8.7 μg/cm2), and its permeation through the skin (∼33 μg/cm2). The performances of vesicles as skin delivery systems were compared with those obtained by water dispersion of allantoin and the commercial gel, Sameplast®. Moreover, in this work, for the first time, the elastic and viscous moduli of the skin were measured, underlining the different hydrating/moisturizing effects of the formulations. The application of ARG liposomes seems to provide a softening and relaxing effect on the skin, thus facilitating the drug accumulation and passage into and trough it.