Solubility enhancement techniques in liquid dosage form

• Solubility enhancement techniques in liquid dosage form are crucial in pharmaceutical development, as they improve the dissolution and bioavailability of poorly soluble drugs.

Various approaches can be employed to enhance solubility specifically in liquid dosage forms

1) Cosolvency

• Description: Involves using water-miscible solvents (cosolvents) to increase drug solubility by altering solvent polarity.

• Examples: Propylene glycol, ethanol, glycerin, polyethylene glycol.

2) Micellar solubilization

• Description: Surfactants form micelles with hydrophobic cores that encapsulate poorly soluble drugs, enhancing solubility.

• Examples: Polysorbate 80, sodium lauryl sulfate, bile salts.

3) Complexation

• Description: Drug forms complexes with agents like cyclodextrins, which have hydrophobic cavities to trap the drug, increasing solubility.

4) Salt formation

• Description: Converts drugs into more soluble salts, particularly for drugs with acidic or basic groups.

• Examples: Sodium, potassium, hydrochloride, sulfate salts.

5) pH adjustment

• Description: Adjusting pH to modify the drug's ionization state, enhancing solubility. Weak acids are more soluble at higher pH; weak bases at lower pH.

6) Hydrotropy

• Description: Uses hydrotropic agents to increase solubility by forming clusters that interact with the drug.

• Examples: Sodium benzoate, sodium salicylate, niacinamide.

7) Emulsification

• Description: Disperses lipophilic drugs in an aqueous phase using emulsifying agents, stabilizing the mixture.

• Examples: Lecithin, glyceryl monostearate, sorbitan esters.

8) Nanoemulsions and microemulsions

• Description: Advanced emulsions with very small droplet sizes to enhance solubility and bioavailability. Requires surfactants and cosurfactants.