Gelified reverse micellar dispersions as percutaneous formulations

This study describes the use of lecithin organogels (LO) as versatile vehicles for percutaneous administration of methyl nicotinate (MN), fenretinide (4HPR) and curcumin (CUR). LO are able to increase the solubility of poor water-soluble molecules probably due to the formation of a short-range hexagonal organization of the lecithin cylindrical reverse micelles. After six months from production, no phase separation and an almost absence of aggregates was observed. LO exhibited similar viscosities and rheological behaviour both in the absence and in the presence of drug. The in vitro drug diffusion from LO studied by Franz cell showed that higher viscous vehicles result in lower diffusion coefficient. The microscopic investigation of human skin displayed no significant alterations after treatment with LO and with PBS. In vivo topical activity on erythema after cutaneous application of LO showed that LO-MN induce a strong erythema, while LO-CUR inhibit skin erythema due to CUR anti-inflammatory activity. Tape-stripping experiments performed on skin after topical administration of LO showed a decrease in the amount of CUR in the stratum corneum after 1 hour from the occlusion. Shelf life stability studies demonstrated the higher stability of LO-HPR as compared to the others drugs.