Eutectic is a single-phase crystalline compound consisting of two or more molecules combined in a certain stoichiometric ratio by non-covalent bonding. Compared with APIs, eutectic crystals have advantages in solubility, dissolution rate, bioavailability, and stability. Therefore, eutectic crystals are an effective method to improve the solubility of BSC class II and class IV compounds.
Drug eutectic refers to the formation of novel co-crystals with specific physicochemical properties by the action of hydrogen or other non-covalent bonds between APIs and eutectic formers. The formation of eutectic provides room for the transformation of amorphous or difficult-to-crystallize APIs into easily handled and stable solid crystals. Co-crystallization of drugs can improve the physicochemical properties (e.g., solubility, dissolution, bioavailability, stability, etc.) of drugs without changing the covalent bonds between APIs molecules.