Development of a self-microemulsifying drug delivery system to enhance oral bioavailability of β-elemene in rats

Our purpose was to develop a self-microemulsifying drug delivery system (SMEDDS) to enhance oral absorption of β-elemene and evaluate its oral bioavailability in rats. Pseudo-ternary phase diagrams were constructed to identify the efficient self-microemulsification region. SMEDDS formulations were further optimized by measurement of mean droplet size and emulsification time. The in vitro release profile of SMEDDS was determined in different aqueous media. The optimal formulation, which consisted of 10 % Miglyol 812, 41.7 % Cremophor EL, 8.3 % Labrasol, 20 % Transcutol P and 200 mg/g β-elemene, demonstrated a higher release rate in simulated gastric fluid than emulsion and pure drug. In vivo studies showed that the relative bioavailability in rats of SMEDDS versus emulsion was 161.35 %. The Cmax for SMEDDS was also significantly higher than that of emulsion (P < 0.05). Our results indicate that SMEDDS is a potential and promising drug delivery system for oral administration of lipophilic Chinese herbal medicines, such as β-elemene.