Effect of the third component on the aging and crystallization of cinnarizine-soluplus® binary solid dispersion

Multiple carriers may be used to prepare solid dispersions (SDs) for different purposes. The aim of this work is to investigate the effect of the third component on the physical stability and physical aging behavior of cinnarizine-soluplus SDs. HPMC, PVP, sorbitol and citric acid were used as the third component to prepare cinnarizine ternary SDs using hot melt extrusion method. The resultant samples were stored at 25 °C or under stress conditions. Differential scanning calorimetry, powder X-ray diffraction and dissolution tests were performed to investigate the changes of samples during the storage. Infrared spectroscopy was used to evaluate the interactions between drug and carriers. Results showed that the addition of HPMC or PVP enhanced the physical stability of ternary SDs stored at 25 °C rather than those stored under stress conditions. Sorbitol did not show any improvements in physical stability of samples stored at 25 °C or under stress conditions. Surprisingly, the physical stability of samples stored at 25 °C or under stress conditions was enhanced significantly by citric acid due to the ionic and hydrogen bonding interactions. The miscibility between drug and carriers as well as between different carriers should be considered when using multiple carriers. The third component can act as a "linker" by interacting with drug and polymer to enhance the physical stability of SDs effectively.