Cosolvents are used to increase the solubility of weak electrolytes, nonpolar molecules and volatile constituents that are used to impart a desirable flavor and odor to the product. Weak electrolytes and nonpolar molecules have poor water solubility. These types of solutes are more soluble in a mixture of solvents than in one solvent alone. This phenomenon is called as cosolvency and the solvents that are used in combination to increase the solubility of the solute are called cosolvents. To increase the water solubility of a drug, another water-miscible solvent is used in which the drug has better solubility. A cosolvent works by reducing the interfacial tension between the aqueous solutions and the hydrophobic drug. Examples of commonly used cosolvents are ethanol, sorbitol, glycerin, propylene glycol and polyethylene glycol.