ABSTRACT
The oral bioavailability of curcumin is limited, attributed to its low solubility or dissolution and poor absorption. Herein, the study describes formulation of curcumin-loaded mixed micelles of Gelucire® 48/16 and TPGS for its dissolution rate enhancement. Curcumin was dispersed in these molten lipidic surfactants which was then adsorbed on carrier and formulated as pellets by extrusion spheronization. Critical micelle concentration (CMC) of binary mixture of Gelucire® 48/16 and TPGS was lower than their individual CMC demonstrating the synergistic behavior of mixture. Thermodynamic parameters like partition coefficient and Gibbs free energy of solubilization indicated that mixed micelles were more efficient than micelles of its individual components in curcumin solubilization. Dynamic light scattering (DLS) suggested slight increase in micellar size of mixed micelles than its components suggesting curcumin loading in mixed micelles. Fourier transform infrared spectroscopy (FTIR) revealed that phenolic hydroxyl group interacts with lipids which contribute to its enhanced solubility. Furthermore, the differential scanning calorimetry (DSC) and X-ray diffraction (XRD) study indicated the conversion of crystalline curcumin into amorphous form. In the pellet formulation, Gelucire® 48/16 acted as a binder and eliminated the requirement of additional binder. Microcrystalline cellulose (MCC) forms wet mass and retards the release of curcumin from pellets. Increase in concentration of water-soluble diluent increased drug release. The optimized formulation released more than 90% drug and maintains supersaturation level of curcumin for 2 h. Thus, mixed micellar system was effective delivery system for curcumin while pellet formulation is an interesting formulation strategy consisting semi-solid lipids.
