Solubility of cefixime in aqueous mixtures of deep eutectic solvents from experimental study and modeling

Deep eutectic solvents (DESs) as green cosolvents can be added to water for increasing the solubility of poorly water-soluble drugs. In this study, the solubility of cefixime is studied in three aqueous solutions of DES, including choline chloride+malonic acid, choline chloride+urea, and choline chloride+glucose. The experiments are conducted in the temperature range of 293.15 K to 333.15 K, pressure of 0.1 MPa and different compositions of the DESs. The results show that adding DES to water increases the solubility of cefixime significantly. For instance, adding 6% (mol/mol) of choline chloride+malonic acid to water increases the cefixime solubility by more than 17 times. The DESs of choline chloride+malonic acid and choline chloride+urea are more effective cosolvents compared with the DES of choline chloride+glucose in increasing the mole fraction of cefixime. In addition, the solubility data are successfully correlated with the activity models of NRTL, Wilson and van Laar. The overall AARD% of the NRTL, Wilson and van Laar models in estimating the mole fraction of cefixime in aqueous solutions of the DESs are 3.88, 3.62 and 10.14, respectively.