Cocrystals of diacerein: Towards the development of improved biopharmaceutical parameters

The effectiveness of Diacerein as an anti-osteoarthritis drug is limited due to its acutely poor aqueous solubility and bioavailability. The present study demonstrates cocrystallization as a successful technique to improve the biopharmaceutical parameters of diacerein. Three cocrystals of diacerein were prepared by an eco-friendly technique with three suitable coformers namely isonicotinamide, nicotinamide, and theophylline. The formation of a new solid phase was inferred from the DSC thermograms and powder diffraction pattern and was supported by FTIR. The crystal structures of the cocrystals determined from the PXRD pattern using Material Studio software. Detailed analysis showed the formation of supramolecular hetero-synthons of complementary functional groups of the coformers with the carbonyl and carboxyl groups of diacerein. The structural conformation of the cocrystalline state was also provided by the shifts in the ssNMR pattern of the cocrystals. The three new cocrystals were found to have a relatively high solubility and intrinsic dissolution rate which showed remarkable improvement in anti-arthritic activity as compared to diacerein. Thus, proving cocrystallization to be a potential solution to the solubility limited bioavailability problems of diacerein.