Supercritical CO 2 versus water as an antisolvent in the crystallization process to enhance dissolution rate of curcumin.

Antisolvent crystallization approach using either water (in conventional crystallization process (WAS)), or supercritical CO 2 (in supercritical anti-solvent crystallization (SCAS)), was employed in presence of hydroxypropyl methylcellulose (HPMC) to enhance the dissolution of curcumin. The impact of pressure, temperature and depressurization time on the SCAS process was studied using the Box-Behnken design to achieve the highest saturation solubility. A physical mixture of curcumin-HPMC was prepared for comparison purposes. Saturation solubility, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction analysis and Fourier transform infrared spectroscopy were conducted to characterize the solid-state characteristics of the crystallized samples. Dissolution studies helped in ascertaining the effects of the crystallization techniques on the performance of the formulation. Curcumin crystalized by different antisolvent displayed varied shapes, sizes, saturation solubility's and dissolution properties. In SCAS process, the maximum saturation solubility (2.83 µg/mL) was obtained when the pressure, temperature and depressurization time were 275 bars, 55 °C, and 22 min respectively. The SCAS samples showed the highest dissolution (70%) in 30 min compared to WAS (27%), physical mixture (18%) and unprocessed curcumin (16%). The improved dissolution rate of SCAS sample originates from the development of sponge-like particles with augmented porosity, decreased crystallinity as well as increased solubility of curcumin.