PENETRATION OF STRATUM CORNEUM BY DOUBLE-LABELLED ULTRADEFORMABLE LIPOSOMES EMPLOYING A NON-OCCLUSIVE TECHNIQUE

JORGE A. M. MONTANARI; LEANDRO A. LADO; LEONARDO RIVADENEYRA; MARÍA J. MORILLA; EDER L. ROMERO

Versailles, Francia

Simposio; Skin and Formulation, 3rd Symposium – Skin Forum, 10 th Annual Meeting; 2009

Purpose: To compare the penetration depth into the stratum corneum of ultradeformable liposomes labelled with Rhodamine-phosphatidyl ethanolamine (Rho-PE) vs. conventional liposomes, employing a Saarbrücken penetration model modified ad-hoc for non occlusive conditions. Methods: 100 nm-sized unilamellar ultradeformable liposomes of soy phosphatidylcholine (SPC)and sodium cholate (NaChol) containing Rho-PE as membrane probe and the green label HPTS (pyranine) as aqueous marker, were non-occlusively applied to human skin explants and incubated 1h at 32ºC, followed by transversal cryosection and observation by confocal laser fluorescence microscope. Conventional (non ultradeformable) double-labelled liposomes were used as control. Results: Confocal images revealed that Rho-PE from ultradeformable liposomes appeared in several stratum corneum layers, until a depth of 14 mm in average, while the HPTS was found in a deeper separate fraction into the viable epidermis, reaching a depth of 24 mm in average. On the contrary, the Rho-PE from conventional liposomes was observed only on the first superficial layer of stratum corneum while the HPTS signal remained absent. Conclusions: The lipid matrix of ultradeformable liposomes deeply entered the stratum corneum, on the coast of losing their aqueous content along the penetration. However, the leaked hydrophilic label could deeply penetrate across the epidermis. On the other hand, only the lipid matrix of conventional liposomes was detected on the surface of the stratum corneum. Hence, only during squeezing of ultradeformable matrices across the stratum corneum, small hydrophilic drugs are released, to be found in deeper skin layers.