Structural Analysis of W/o/w Multiple Emulsions by Means of Dsc

W/o/w emulsions have numerous advantages arising from their structure, achieving e.g. sustained drug delivery and simultaneous use of active ingredients incompatible with each other. They are widely used both in cosmetic and in pharmaceutical industry. Studying their complex structure is quite a difficult task, which entails great care. The presently available methods give information about the presence of the multiple droplets, about their structure and size distribution directly or indirectly. Microscopic techniques can be used as direct method for droplets analysis; indirect methods involve e.g. use of indicator compounds, rheological measurements [1]. The aim of the present study was to apply, adopt and combine different methods, which are well known, but not widely used for emulsion systems, specially not in case of multiple ones. Microscopic observations combined with differential scanning calorimetry (DSC) measurements were used in order to identify the formed structure, at developmental stage in case of different components, preparation methods, and stirring rates. Thermoanalytical examinations have increasing role in structural investigation of different pharmaceutical substances and dosage forms, including multiple emulsions [2–6]. The majority of the publications are limited to the examination of solid pharmaceuticals, the number of publications relating to semisolid medications and cosmetics is insignificant in comparison. Therefore our research group, in line with its research profile dating back to decades, performed thermogravimetric examinations to verify the microstructure of o/w creams and to detect the factors contributing to structure formation [7].