Size characterization of lipid-based self-emulsifying pharmaceutical excipients during lipolysis using Taylor dispersion analysis with fluorescence detection

Self-emulsifying drug delivery systems based on lipids have gained in interest in recent years due to their capacity to enhance the bioavailability of poorly water soluble drugs. Their oral intake suggests that they will be in contact with gastric and pancreatic enzymes during their passage through the gastrointestinal tract. The study of the evolution of such systems in the presence of enzymes is thus essential to develop better drug delivery vehicles. In this work, the lipolysis of two lipid based self-emulsifying drug delivery systems, Labrasol (R) and Gelucire (R) 44/14 by pancreatic enzymes and under conditions mimicking the gastrointestinal tract are presented. The following of the digestion is realized by Taylor dispersion analysis using fluorescent detection. A hydrophobic marker was used to tag the microdroplets. Results have shown that, Labrasol (R) droplets decrease exponentially in size with lipolysis time, from 11.8 nm to 3.5 nm in 20 min. On the contrary, Gelucire (R) 44/14 droplets increased sigmoidally in size from 5.6 to 24.7 nm. Even after 120 min lipolysis, both systems maintained a solubilizing capacity of the hydrophobic marker.