Ionic Liquids for Increasing the Solubility of Sparingly Soluble Drug Molecules

Ionic liquids (ILs) have attracted considerable attention as green alternatives to conventional toxic organic solvents. They have several advantageous properties that make them potentially useful in various areas of modern science, especially drug delivery. Owing to their intrinsic tunability and exceptional properties, ILs are undoubtedly capable of addressing the drawbacks associated with sparingly soluble drugs, such as polymorphism, limited solubility, and poor bioavailability. ILs can be used as replacements for conventional volatile organic solvents. Their task-specific optimization at the molecular level can be exploited to obtain effective drug formulations. The structural properties of ILs can be tailored by altering their constituent anions and cations to improve the pharmacokinetic and pharmacodynamic properties and biological activities of drugs. This chapter describes the progress of IL-related research in pharmaceutics. It comprises a discussion of the use of ILs, either as solubilizing agents or solvents/carriers for pharmaceutical drugs. Specifically, the chapter deals with the use of ILs as potential solvents/agents for dissolving sparingly soluble drugs, and with the exploitation of the possible mechanism by which ILs increase solubility. An understanding of the ionic interactions between drug molecules and ILs in an aqueous solution will also stimulate innovative IL-based technologies and the use of ILs in pharmaceuticals and medicine.