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

Abstract

The therapeutic applications of curcumin, a phenolic compound extracted from <i>Curcuma</i> 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^® 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 <i>Curcuma</i> species, <i>viz. C. longa</i> (S-CL1) and <i>C. aromatica</i> (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 ∼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 <i>vis-à-vis</i> 22-fold in S-Eo3 compared to curcumin suspension. All the SMEDDS formulations were stable for three months as established by ICH guidelines.