Tween 80-based mixed micelles as felodipine carriers in aqueous medium

UV spectroscopy, precise turbidimetry, and refractometry are employed to measure the solubilization of the lipophilic compounds felodipine (F) (drug) and nonionic surfactants glyceryl monooleate (GMO) and glyceryl monolaurate (GML) (efficient promoters of skin permeability (enhancers)) in aqueous solutions of Tween 80 (Tw). An increase in the concentration of Tw makes it possible to enhance the solubility of the drug by a factor of 10²–10³ and above as compared to F solubility in water. The effect becomes stronger in the presence of an enhancer. The following properties of Tw + F, Tw + GMO, Tw + GML, Tw + GMO + F, and Tw + GML + F micelles are studied: the aggregation numbers of the components, localization of solubilizates, diffusion coefficients, sizes, and degrees of hydration. Experimental data on the kinetics of drug mass transfer by micelles are in good agreement with the calculations performed within the framework of diffusion theory. Tw-based mixed micelles are found to be efficient carriers of F and enhancers in aqueous media, which is of importance for the creation of systems for delivery of lipophilic drugs in a bioavailable form.