This range is considered ideal because it allows for good solubility of both polar and non-polar compounds, making it suitable for a wide range of drug formulations. Cosolvents with dielectric constants outside of this range may not be as effective in solubilizing the desired drug compound or may have other undesirable effects on the formulation. Additionally, cosolvents with dielectric constants below 25 may not provide enough solubilizing power, while those above 80 may result in excessive solubility, leading to formulation instability or precipitation of the drug compound.
