Preparation, physicochemical characterization and solubility evaluation of pharmaceutical cocrystals of cinnamic acid

Cocrystals have wide applicability in the field of pharmaceutical sciences, promoting improvements in the physicochemical properties of the drugs. Trans-cinnamic acid (TCA) is a secondary plant metabolite, which has several pharmacological activities and presents as an intrinsic characteristic of low aqueous solubility. The aim of this work was the preparation, characterization and evaluation of solubility of TCA cocrystals. The cocrystals were prepared in 1:1 molar ratio of TCA and coformers, employing the solvent evaporation method. The samples were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The solubility of cocrystals was evaluated by shaker-flask method for 24 h. PXRD data showed the potential formation of three cocrystals, from the appearance of new peaks in the diffraction pattern and discarded the occurrence of polymorphism due to no changes in the crystalline pattern. DSC curves showed that the possibility of potential cocrystals formation is associated with a decrease in the melting temperature of the raw materials isolated in the samples, and the FTIR spectroscopy showed changes in the vibration frequencies of the possible functional groups involved in hydrogen bonding. SEM images showed changes in TCA morphology and coformers in cocrystals. Moreover, the solubility of cocrystals showed a significant increase in the aqueous media. The results showed that it is possible to improve aqueous solubility by obtaining cocrystals.