Enhancement of Curcumin Solubility Using a Novel Solubilizing Polymer Soluplus®

Abstract

In this study, a novel solubility enhancement excipient (Soluplus®) was investigated to improve the solubility and dissolution rate of Curcumin, a poorly water soluble drug. Various methods were utilized for the fabrication of Curcumin-Soluplus® mixtures, including the physical mixture, co-grinding, milling physical mixture, and solid dispersion. The drug and polymer mixtures were prepared in a polymer ratio from 10–50% w/w. Curcumin-Soluplus® mixtures were evaluated using Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The order of enhanced solubility was as follows: solid dispersion > co-grind > milling physical mixture > physical mixture. Moreover, the enhanced solubility and drug dissolution increased with increasing polymer ratio. Results of the Fourier transform infrared spectroscopy revealed no chemical interaction between the Curcumin and Soluplus® in physical mixtures, milling physical mixtures, and co-grinding mixtures. The differential scanning calorimetry and X-ray diffraction studies revealed that Curcumin was in an amorphous state in the mixtures prepared by the solid dispersion method. The drug formulated in the solid dispersion method was rapidly and almost entirely dissolved and released the drug within 2 h in 0.5% w/w sodium lauryl sulfate dissolution medium. The Soluplus® showed a significant enhancement in the solubility and in vitro release performance of Curcumin. The solid dispersion is a promising method to enhance the solubility and dissolution rate of Curcumin using Soluplus®.