Solid–Liquid Phase Equilibrium and Ternary Phase Diagrams of Telmisartan-Saccharin Cocrystal in Methanol, Ethanol, and Methanol/Chloroform Mixtures at 298.15 and 313.15 K

In this work, ternary phase diagrams of telmisartan-saccharin (TEL-SAC) cocrystal in methanol, ethanol, and quasi-ternary sections of the quaternary system TEL-SAC–chloroform–methanol were determined at 298.15 and 308.15 K. The results show that the stable region of cocrystal is greatly biased towards SAC in methanol and ethanol; this is due to the large solubility difference between TEL and SAC. In the mixed solvent of chloroform and methanol, the cocrystal stable region appears at the center of the whole phase diagram when the mass fraction of chloroform is 80%, which indicated that the solubility difference between TEL and SAC in the mixed solvent was relatively small. Moreover, the solubility behavior of TEL-SAC cocrystal was studied and the results showed that the solution complexation model in methanol and ethanol was 1:1 + 1:2, and the complexation model in chloroform and binary mixtures of chloroform/methanol was 1:1.