Study on the Formation Mechanism of Doramectin Solvate and the Desolvation Process

Doramectin is a broad-spectrum antiparasitic drug used in veterinary medicine. However, there have been no reports on doramectin solvates and their formation mechanisms so far. In this study, three doramectin solvates, doramectin-ethyl acetate (S1), propyl acetate (S2), and butyl acetate (S3), were successfully prepared using the solution crystallization method. Single-crystal X-ray diffraction analyses confirmed that all three solvates are isomorphous crystals. Additionally, the crystal structure results revealed that solvent molecules form hydrogen bonds with doramectin in a 1:1 molar ratio and exist in a channel-like structure. Furthermore, the desolvation temperature of these solvates was positively correlated with the strength of the intermolecular interactions. Overall, this study provides a significant theoretical foundation and methodological guidance for research on doramectin solvates and their subsequent formulation development as well as providing valuable references and research approach for the development of more solid forms of doramectin.