solubilization

Solubilization is a clever trick for dissolving the undissolvable: it hides an oily, water-hating drug inside tiny soap-like spheres that float happily in water. The drug never really dissolves in the water itself — it is smuggled along inside these microscopic carriers.

The carriers are micelles, which form when surfactant molecules — each with a water-loving head and an oil-loving tail — gather above their critical micelle concentration into clusters with their tails tucked inward. A poorly water-soluble drug partitions into this oily core, so the apparent (total) amount of drug the system can hold rises far above the drug's true aqueous solubility, even though the water phase stays clear.

Solubilization is widely used for hydrophobic drugs, vitamins, essential oils and some injectables; the surfactant Polysorbate 80 and bile salts are common solubilisers. The limits are practical: surfactants can irritate tissues or cause toxicity at high levels, may interact with the drug or container, and the solubilised drug must still release from the micelles to be absorbed.