Lecithin based nanoemulsions: A comparative study of the influence of non-ionic surfactants and the cationic phytosphingosine on physicochemical behaviour and skin permeation.

Charged drug delivery systems are interesting candidates for the delivery of drugs through skin. In the present study, it was possible to create negatively and positively charged oil/water nanoemulsions by using sucrose laureate and polysorbate 80 as non-ionic surfactants. The positively charged nanoemulsions were generated by adding cationic phytosphingosine (PS). The relationship between the physicochemical properties of the nanoemulsions was shown by particle size and zeta potential measurements. These properties were dependent on the type of non-ionic surfactant and the concentration of PS. Furthermore the cationic PS had a positive impact on the skin permeation rates (flux) of the incorporated model drugs fludrocortisone acetate and flumethasone pivalate. An enhancement factor between 1.1 and 1.5 was obtained in relation to the control. The interaction of pre-impregnated porcine skin with positively and negatively charged nanoemulsions was confirmed by DSC analysis. The generated DSC-curves showed a slight difference in the phase transition temperature assigned to the characteristic lipid transition. However, it was not possible to assign the effect to one of the ingredients in the multicomponent system.