Percutaneous absorption of sunscreens from liquid crystalline phases

• Published in: Journal of controlled release Vol. 60; no. 1; pp. 67 - 76
• Main Authors: Brinon, Laure, Geiger, Sandrine, Alard, Valérie, Doucet, Jean, Tranchant, Jean-François, Couarraze, Guy
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 28-06-1999; Elsevier
• Subjects: Animals; Biological and medical sciences; Crystallization; Cutaneous permeation; Diffusion; General pharmacology; In Vitro Techniques; Liquid crystal; Medical sciences; Nonionic surfactant; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Skin Absorption; Sunscreen; Sunscreening Agents - administration & dosage; Sunscreening Agents - pharmacokinetics; Surface-Active Agents - administration & dosage; Surface-Active Agents - chemistry; Swine; Liquid crystal; Sunscreen; Diffusion; Cutaneous permeation; Nonionic surfactant; Pharmaceutical technology; Non ionic surfactant; Permeation; Liquid crystals; In vitro; Pig; Vertebrata; Mammalia; Absorption; Animal; Dosage form; Skin; Sunscreen product; Absorption enhancer; Artiodactyla; Diffusion coefficient; Ungulata
• ISSN: 0168-3659; 1873-4995
• DOI: 10.1016/S0168-3659(99)00054-1

The purpose of the present study was to investigate the effects of two nonionic surfactants with liquid crystalline structures on the cutaneous availability of two sunscreens. Three liquid crystalline structures were investigated: lamellar, hexagonal and cubic. The diffusion of sunscreens within the liquid crystals was determined by measuring transport kinetics into an unloaded surfactant medium from a similar system loaded with the sunscreens. The diffusion coefficients were the greatest in the cubic systems for benzophenone-4 (a hydrosoluble sunscreen) and in lamellar systems for octyl methoxycinnamate (a liposoluble sunscreen). So the diffusion in this surfactant systems was strongly dependent on the structure of the liquid crystal and on the physicochemical properties of the solute. The transcutaneous fluxes were determined using a Franz-type diffusion cell. The liquid crystalline vehicles modified the transcutaneous fluxes of benzophenone-4 but did not change those of octyl methoxycinnamate. The solute diffusion within the vehicle was not the rate-determining step for transcutaneous permeation for either sunscreen. The diffusion of benzopenone-4 within the stratum corneum and that of octyl methoxycinnamate within the dermis could be the rate-determining steps for their transcutaneous permeation. These two steps could be affected differently by nonionic surfactant vehicles.