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30/10/2025, 00:02 Pharmaceutical Solutions & Sterile Dosage Forms

Methods to modify Solid solubility in
liquids

1. Co-solvency 5. Solubilization
2. Complexation 6. PH control
3. Chemical modification 7. Surface active agents (Micellar formation)
4. Particle size reduction 8. Pro-drug formation

Co-solvency

Water does not dissolve many drug compounds to a sufficient degree to enable the
preparation of a pharmaceutical solution.

Co-solvents are water-miscible liquids with greater drug solubility and hence are added to
water to enhance drug solubility.

Co-solvents are often used to increase the water solubility of drugs which do not contain
ionizable group(s) and whose solubility can thus not be increased by pH adjustment.

When a solute is more soluble in a mixture of solvents than in one solvent alone, this
phenomenon is known as cosolvency, and the solvents that, in combination, increase
the solubility of the solute are called cosolvents.

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