To compare three different curcumin-loaded solid dispersions, assess their solubility, and conduct antioxidant and biological safety assays.

Three different curcumin-loaded solid dispersions were prepared using the solvent, solvent melting, and melting methods, and characterized using a scanning electron microscope, differential scanning calorimeter, and X-ray diffractometer. Additionally, the drug content, equilibrium solubility, dissolution, 1,1-diphenyl-2-picrylhydrazyl, 2,2ʹ-azinobis-(3-ethylbenzthiazoline-6-sulphonate) scavenging ability, and biological safety were investigated.

X-ray diffractometer and differential scanning calorimetry analyses confirmed that curcumin existed in an amorphous state in the solid dispersion, while Fourier-transform infrared spectroscopy suggested intermolecular interactions between curcumin and polyvinylpyrrolidone K29/32, and scanning electron microscope showed the disappearance of crystalline morphology and formation of a homogeneous matrix. The optimized solid dispersion significantly improved the aqueous solubility of curcumin. Rapid drug release was observed, with more than 70% of curcumin released within 20 min, whereas free curcumin exhibited very limited dissolution. The solubility of the solid dispersion was potential of hydrogen-dependent, with higher solubility under weakly acidic to near-neutral conditions and a marked decrease under alkaline conditions. In antioxidant assays, the solid dispersion exhibited stronger free radical scavenging activity than curcumin alone in a concentration-dependent manner. In addition, the solid dispersion showed reduced cytotoxicity, with improved cell viability compared with free curcumin at higher concentrations.

Solid dispersions supported by polyvinylpyrrolidone K29/32 showed significantly increased solubility of curcumin, and had higher antioxidant activity and biological safety than those of curcumin alone.