Oral delivery of coix seed oil in o/w microemulsion: Preparation, characterization, and in vitro and in vivo evaluation

Abstract

In this study, oral coix seed oil microemulsion (CSOME) was prepared to improve coix seed oil (CSO) bioavailability. The morphology, encapsulation efficiency, active ingredient loading, droplet size, stability, in vitro release kinetics, tissue distribution and CSOME pharmacokinetics were investigated. Data on the oral CSO liposome and microcapsule in previous studies were also included for comparison. The composition of CSOME with high oil loading was EL-40/Span 80/ethanol/coix seed oil/distilled water, and the main parameters of this formulation were 5:1 w/w ratio of EL-40/Span 80 and 3:1 of Km. The CSOME was spherical with the droplet size of 36.2 nm. The in vitro release rate and stability of CSO were significantly improved by loading into the microemulsion. The in vitro release kinetics of CSO from CSOME was best fitted with Ritger-Peppas equation (0.5 < n < 1.0). In addition, CSO from CSOME exhibited sustained release and high bioavailability in vivo was mainly distributed in the liver, lungs and kidneys.