Enhancement of loading and oral bioavailability of curcumin loaded self-microemulsifying lipid carriers using Curcuma oleoresins

The therapeutic applications of curcumin, a phenolic compound extracted from Curcuma species, is limited due to poor bioavailability. To enhance the bioavailability, self-microemulsifying drug delivery systems (SMEDDS) with curcumin were prepared. Ethyl oleate, Tween 80, and Transcutol(R) P with surfactant: co-surfactant ratio of 2:1 w/w was selected based on the solubility and pseudo-ternary phase diagrams. The optimized formulation (S-Eo3) was evaluated for use of spice oleoresins as curcumin bioenhancers. The oleophilic phase of curcumin containing SMEDDS formulations was then successfully modified by using bioactive oleoresins extracted from two Curcuma species, viz. C. longa (S-CL1) and C. aromatica (S-CA1). The curcumin content in S-Eo3, S-CL1, and S-CA1 were 69.6 +/- 0.23, 82.4 +/- 0.62, and 88.8 +/- 0.46 mg/g, respectively. Thus, by the partial modification of oleophilic phase of SMEDDS with spice oleoresin (acting as bioenhancer) resulted in similar to 88 k improvement of curcumin aqueous solubility. The pharmacokinetic study in male Wistar rats showed that the relative bioavailability of curcumin in S-CL1 and S-CA1 were 26- and 29-fold vis-a-vis 22-fold in S-Eo3 compared to curcumin suspension. All the SMEDDS formulations were stable for three months as established by ICH guidelines.