Solid-state properties, solubility, stability and dissolution behaviour of co-amorphous solid dispersions of baicalin

Baicalin (BL) is a natural, potential therapeutic molecule with a wide range of biological activities. However, poor aqueous solubility, low stability, and slow dissolution are the major limitations of BL. Co-amorphous systems are new and emerging systems that are single-phase, multicomponent amorphous systems consisting of one or more small co-former with a hydrophobic drug. The co-former helps in improving the physicochemical properties of the hydrophobic drug without affecting its pharmacological properties. The objective of this study was to prepare co-amorphous solid dispersions of baicalin (BSDs) using organic acids and amino acids to enhance its solubility, stability and dissolution profiles. The BSDs were prepared in a molar ratio of 1 : 1 of drug and co-former by the solvent evaporation method. The prepared BSDs were characterized by powder XRD and DSC analysis for determining the physical solid-state of BL, and by FTIR to determine possible intermolecular interactions between BL and co-formers. The BSD prepared with histidine (BL-His) showed a perfect co-amorphous system with an approximately 60-fold increase in solubility, complete loss of crystallinity, and complete dissolution of BL within 15 min in simulated intestinal buffer. Further, BL-His showed physicochemical stability over a period of six months without any sign of recrystallization and loss of drug. Therefore, instead of the native and crystalline BL, the use of BL-His could be a better approach for pharmaceutical applications of BL.