Solid–Liquid Equilibrium Solubility Determination, Modeling, and Thermodynamic Analysis of Ciclopirox Olamine in Ten Monosolvents and Binary Mixed Solvents from 283.15 to 328.15 K

CPO (ciclopirox olamine) is a broad-spectrum antifungal agent, and there is currently a lack of research on its solubility. The solubility of CPO in ten monosolvents and binary solvents at different ratios was determined using the static method at temperatures ranging from 283.15 to 328.15 K. The dissolution behavior consistently followed the pattern of increasing solubility with rising temperature. Experiment demonstrated that CPO exhibited the highest solubility in n-octanol and the lowest solubility in ethyl acetate. Furthermore, the experimental results were interpreted using analysis of solvent polarity, Hansen solubility, and KAT-LSER equations and concluded that the favorable solvents of CPO tend to possess strong hydrogen-bonding donor properties, moderate polarity, and strong solvent interaction capability. The experiment characterized CPO using Differential Scanning Calorimetry (DSC). And, X-ray diffraction (XRD) measurements indicated no changes in crystal structure during the experimental process. Solubility data for the ten monosolvents were correlated using Apelblat, Van’t Hoff, Jouyban, and non-random two-liquid (NRTL) equations. Binary solvent solubility data were correlated using Apelblat, Van’t Hoff, Grafting Solvation Model (GSM), Non-Random Two-Liquid (NRTL), Sun, and Apelblat–Jouyban–Acree equations. The RMSD and ARD values for all data are relatively small, indicating excellent structural model fitting.