255530 Formation of Itraconazole-Succinic Acid Cocrystals by CO2 Antisolvent Cocrystallization

Thursday, November 1, 2012: 9:14 AM
Oakmont (Omni )
Courtney A. Ober and Ram B. Gupta, Chemical Engineering, Auburn University, Auburn, AL

Cocrystals of itraconazole, an antifungal drug with poor bioavailability, and succinic acid, a water-soluble dicarboxylic acid, were formed by gas antisolvent (GAS) cocrystallization using pressurized CO2 to improve itraconazole dissolution. In this study, itraconazole and succinic acid were simultaneously dissolved in a liquid solvent, tetrahydrofuran, at ambient conditions. The solution was then pressurized with CO2, which decreased the solvating power of tetrahydrofuran and caused precipitation of itraconazole-succinic acid cocrystals. A fundamental understanding of cocrystallization in a CO2-expanded liquid was obtained by modeling the equilibrium concentrations of drug and former in solution as a function of pressure using the Peng-Robinson equation of state and AspenTech software. The cocrystals prepared by GAS cocrystallization were compared to those produced using a traditional liquid antisolvent, n-heptane, for size and surface morphology, crystallinity, thermal behavior, chemical structure, clinical relevance, and stability. Scanning electron microscopy, powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy analyses showed that itraconazole-succinic acid cocrystals with physical and chemical properties similar to cocrystals produced using a traditional liquid antisolvent technique can be prepared by CO2 antisolvent cocrystallization. The dissolution profile of itraconazole was significantly enhanced through GAS cocrystallization with succinic acid, achieving over 90% dissolution in less than 2 hours. The cocrystals appeared stable against thermal stress for up to 4 weeks under accelerated stability conditions, showing only moderate decreases in their degree of crystallinity but no change in their crystalline structure. This study shows the utility of an itraconazole-succinic acid cocrystal for improving itraconazole bioavailability while also demonstrating the potential for CO2 to replace traditional liquid antisolvents in cocrystal preparation, thus making cocrystal production more environmentally benign and scale-up more feasible.

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