Self-nanoemulsifying drug delivery system (SNEDDS) for oral delivery of Zedoary essential oil: Formulation and bioavailability studies

The aim of the present study was to develop a self-nanoemulsifying drug delivery system (SNEDDS) for the oral delivery of Zedoary turmeric oil (ZTO), an essential oil extracted from the dry rhizome of Curcuma zedoaria. Pseudo-ternary phase diagrams were constructed to identify the efficient self-emulsification regions. ZTO could serve as a partial oil phase with the aid of the second oil phase to enhance drug loading. Increasing the surfactant concentration reduced the droplet size but increased the emulsification time, while the reverse effect was observed by increasing the co-surfactant concentration. Based on the emulsification time, droplet size and zeta potential after dispersion into aqueous phase, an optimized formulation consisting of ZTO, ethyl oleate, Tween 80, transcutol P (30.8:7.7:40.5:21, w/w) and loaded with 30% drug was prepared. Upon mixing with water, the formulation was rapidly dispersed into fine droplets with a mean size of 68.3 ± 1.6 nm and ξ-potential of −41.2 ± 1.3 mV. The active components remained stable in the optimized SNEDDS stored at 25 °C for at least 12 months. Following oral administration of ZTO-SNEDDS in rats, both AUC and Cmax of germacrone (GM), a representative bioactive marker of ZTO, increased by 1.7-fold and 2.5-fold respectively compared with the unformulated ZTO.