Multi-component Crystal Strategy for Improving Water Solubility and Antifungal Activity of Climbazole.

Purpose: The primary problem with climbazole (CLB), a broad-spectrum imidazole antifungal drug, is its low water solubility. In order to increase its water solubility and antifungal activity, three new multi-component crystals were synthesized in this work, and the intermolecular interactions were systematically studied. This work helps to optimize the CLB product formulation and extend its application prospects.

Methods: In this work, three novel multi-component crystals, CLB-malonic acid (CLB-MA) salt, CLB-succinic acid (CLB-SA) cocrystal and CLB-adipic acid (CLB-AA) cocrystal, were successfully synthesized. And the crystal structure, thermodynamic properties, solubility, dissolution, hygroscopicity, and antifungal activity of the three multi-component crystals were fully characterized by single-crystal X-ray diffraction (SCXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic water vapor adsorption (DVS) and powder dissolution tests, etc. The molecular interactions and molecular stacking in multi-component crystals were studied by Hirshfeld surface (HS), molecular surface electrostatic potential (MEP), interaction region indication (IRI) and atom and molecule (AIM) techniques.

Results: The results show that the three multi-component crystals have good moisture resistance stability, and their water solubility is 6-22 times that of pure CLB. Meanwhile, the measurement of the minimum inhibitory concentration (MIC) proves that the cocrystal/salt has a stronger antifungal activity than climbazole. Quantum chemistry calculations of crystal structure visualized and quantified the interactions that exist in multi-component crystals, and explored the microscopic mechanisms underlying the different performance of multi-component crystals.