Modulated release of triterpenic compounds from a O/W/O multiple emulsion formulated with dimethicones: infrared spectrophotometric and differential calorimetric approaches

From the use of silicones within O/W/O multiple emulsions, we can expect, t wo principal advantages: (1) the silicones with the lowest molecular weight decrease the oily touch; (2) due to the large range of viscosity, this exc ipient should influence the skin distribution of actives after topical appl ication. The purpose of our work is to highlight these advantages. Multiple emulsions were formulated with several dimethicones and with drug model. F irstly, the effects of different dimethicones incorporated within multiple emulsions were studied, through in vitro penetration results. Secondly, we investigated the residual film on the skin by Differential Scanning Calorim etry (DSC) and by Fourier Transform Infrared (FTIR) to determine its struct ure. Correlations were established between the silicone structure and the d istribution of drugs in different skin levels or between the silicone struc ture and the percutaneous penetration. The incorporation of silicones withi n O/W/O multiple emulsions seems to be an efficient means of modulating the penetration and the distribution of drugs in the skin. (C) 2000 Elsevier S cience B.V. All rights reserved.