Ionic Liquid Forms of Carvedilol: Preparation, Characterization, and Solubility Studies

Purpose Pharmaceutically active compounds (API) in solid form have several disadvantages which may include polymorphism, poor solubility, and low bioavailability. To overcome these issues, API-based ionic liquids have been proposed to solve this problem. Methods Solvent evaporation method was selected to prepare ionic liquid forms of CVD. A binary mixture of CVD with citric acid, tartaric acid, and saccharin in 1:1 M ratio was dissolved in 5 ml of methanol then they left 4 days for solvent evaporation. The solubility of CVD and prepared ionic liquids were measured in different media. Results A viscous yellow liquid in all cases was obtained. More than three-unit differences between pK(a) of CVD and studied compounds and characterization by different instrumental analysis methods confirmed the formation of an ionic liquid form of CVD and the prepared ionic liquids could significantly change the solubility of CVD. Conclusion Overall, ionic liquids of CVD could be used for overcoming the disadvantages of its solid form and increasing CVD solubility. However, pH, type, and concentration of dissolution medium and the solubility of counter-ions are critical issues which they should be considered in evaluating solubility of CVD and its ionic liquid forms.