Curcumin Eutectics with Enhanced Dissolution Rates: Binary Phase Diagrams, Characterization, and Dissolution Studies

Curcumin is a potentially viable pharmaceutical ingredient obtained from the rhizome of a turmeric plant, Curcuma longa. It is a polyphenolic compound which is known to possess antibacterial, anti-inflammatory, antitumor, and anticancer properties. Its use in pharmaceutical applications has been limited because of its poor aqueous solubility and hence poor bioavailability. In this work, attempts were made to formulate new solid forms of Curcumin with several coformers, mainly to enhance the dissolution rate of curcumin in aqueous medium. Ibuprofen, succinic acid, paracetamol, carbamazepine, ethyl paraben, glycine, tyrosine, N-acetyl d,l-tryptophan and biotin are the coformers investigated in this study. Binary phase diagrams were constructed for each binary system which helped in identifying the nature and the composition of the solid phase. All binary systems except curcumin–ibuprofen exhibited eutectic formation. The curcumin–ibuprofen system resulted in a physical mixture. These solid phases were further characterized through powder X-ray diffraction, differential scanning calorimetry, Fourier transform infrared spectroscopy and Raman spectroscopy. Dissolution studies conducted for eutectics showed enhanced dissolution rates as compared to raw curcumin. The results obtained were compared with the literature reports to present a consolidated account of research being conducted to enhance aqueous solubility of curcumin by developing new solid forms of curcumin such as eutectics, coamorphous solids, and cocrystals. Further, attempts have been made to understand how molecular geometry and intermolecular interactions influence the formation of a specific solid form.