Solubility Enhancement of Caffeine and Furosemide Using Deep Eutectic Solvents Formed by Choline Chloride and Xylitol, Citric Acid, Sorbitol or Glucose

The low solubility of active pharmaceutical ingredients (APIs) in aqueous medium hinders the formulation of drugs in liquid solvents. Several methodologies are used to improve their solubilities being one of them the use of Deep Eutectic Solvents (DES). In this work 10 DES formed by xylitol, citric acid, sorbitol and glucose (HBD) and choline chloride as HBA have been prepared. The solubility of caffeine and furosemide in these DES and their stability have been studied. Additionally, their volumetric and rheological properties have been analysed. Results show that in the case of caffeine, the increase of water content, increase the solubility. This trend is the opposite in the case of furosemide. The stability study reveals that the concentrations of API in DES have been stable during the test time. Finally, the rheological study shows that all studied DES are non-Newtonian fluids, with viscosities decreasing when water content increases.