Co-solvents are substances added in small amounts to immiscible solutions to increase the solubility of poorly soluble compounds and allow them to mix. Common co-solvents like ethanol, propylene glycol, and glycerin have properties of being non-toxic, non-irritating, and having dielectric constants between 25-80, making them suitable for oral and parenteral use. A 2009 study found the use of a co-solvent increased the solubility of various anti-diabetic drugs by over 500 times. Co-solvents work by reducing the interfacial tension between water and hydrophobic solutes, forming a one-phase solution.

1. Co-solvents
Solution: A homogenous mixture of two or
more substances.
Co-solvants: substances added to an
immiscible solution in small amounts to
increase the solubility of a poorly-soluble
compound and make them mixable to each
other.

2. • common cosolvents for this purpose are
ethanol, propylene glycol, glycerin, sorbitol
and polyethylene glycol.

3. cosolvents characteristics
Non-toxic
Non-Irritancy
Values of Dielectric constant is in between 25-80
Specially for oral and parenteral use

4. Application
• Evidenced by a 2009 study in which
researchers from Panjab University showed
the solubility of various anti-diabetic drugs
has been increased by more than 500 times by
use of a cosolvent.

5. How does it work
• Cosolvent system works by reducing the
interfacial tension between the aqueous
solution and hydrophobic solute thus making
the one-phase solution.