nanocrystal

A nanocrystal is the drug itself ground down to nanometre size, with no carrier material around it apart from a thin layer of stabiliser. Unlike a liposome or polymeric particle that wraps a drug inside something else, a nanocrystal is almost pure drug — picture a sugar cube crushed into an exceedingly fine powder so that it dissolves in your tea far faster than the whole cube would.

The reason this works is geometry. Making particles smaller hugely increases the surface area exposed to the surrounding fluid, and a larger surface dissolves faster, as described by the Noyes–Whitney relationship. At the nanoscale the curvature is so extreme that even the equilibrium solubility rises slightly. The practical payoff is dramatically improved dissolution and absorption for poorly water-soluble drugs.

Nanocrystals are made by milling or by precipitating the drug under controlled conditions, and they must be stabilised by surfactants or polymers, because such tiny particles are desperate to clump back together or grow into bigger crystals over time. They are valued precisely because they let a drug be almost entirely active ingredient, but keeping them stable as a dry powder or a liquid dispersion is the central manufacturing challenge.