Experimental design and partial least squares in the study of complex mixtures: microemulsions as drug carriers

Four-component non-aqueous microemulsions, containing lecithin, taurodeoxycholic acid, ethyl oleate and 1,2-propylene glycol have been studied with chemometric techniques to emphasize the role of the components on the release of a drug. Since microemulsions can be obtained only for particular proportions of the constituents, their realm of existence was determined by using Doehlert experimental design. Successively, a mixture design technique was applied to select the set of microemulsions for the measurement of the diffusion rate of a model lipophilic drug, retinol, through a hydrophilic membrane. The drug permeability was modelled as a function of the mixture composition by partial least squares (PLS). The results emphasize the role of the cosurfactant and the oil phase of the system on the drug permeation behaviour from the waterless microemulsion.