A favourable solubility of isoniazid, an antitubercular antibiotic drug, in alternative solvents

The sufficient solubility of isoniazid in alternative solvents obtained in this work can open new perspectives in pharmaceutical processing. Solid–liquid equilibrium (SLE) measurements have been made using a dynamic (synthetic) method. The melting point and the enthalpy of fusion of isoniazid were acquired using differential scanning calorimetry (DSC). The solubility of isoniazid in bis(trifluoromethylsulfonyl)amide ionic liquids was found to be significantly lower than in the studied trifluoromethanesulfonate ionic liquid. The best solvent amongst studied for this common antibiotic against tuberculosis was discovered. The solid–liquid phase equilibria were described using the six different correlation equations which revealed relatively good description with the acceptable standard deviation temperature range.

► Development of sustainable solvents targeted to pharmaceutical application.
► Applicable solubilities of isoniazid in ionic liquids for pharmaceutical processing.
► Alternative solvents suitability in substitution of flammable and volatile solvents.
► The sufficient solvent was found out.
► Ionic liquids can compete in safer mode with solvents used in pharmaceutical industry.