Preparation and oral bioavailability study of curcuminoid-loaded microemulsion.

Curcuminoid, a dietary polyphenolic compound, has poor water solubility and low bioavailability following oral administration. The aim of this study was to develop a formulation of curcuminoid-loaded microemulsion (Cur-ME) to improve its oral bioavailability. The optimized Cur-ME formulation was prepared by using labrafac lipophile WL 1349, cremophor RH 40, and glycerine as the oil phase, the surfactant, and the cosurfactant, respectively. Pharmacokinetics and bioavailability of curcuminoid suspension and Cur-ME were evaluated and compared in rats. Plasma bisdemethoxycurcumin (BDMC), treated as the representing component of curcuminoid, was determined by high-performance liquid chromatography with fluorescence detector. After gavage administration of curcuminoid suspension, the plasma BDMC level was very low, below 5 ng/mL, whereas for Cur-ME, double peak of maximum concentrations were observed. The relative bioavailability of Cur-ME was enhanced in an average of 9.6-fold that of curcuminoid suspension. It was concluded that the bioavailbility of curcuminoid was enhanced greatly by the microemulsion.