A problem worth solving

Most medicines are not available in liquid form because over 50% of all drugs are insoluble, or only sparingly soluble, in water or any other pharmaceutically acceptable solvent.

To be administered as a liquid, an insoluble drug must first be suspended. However, suspended medicines undergo sedimentation on standing, leading to a risk of under or overdosing.

In addition, only relatively low concentrations of insoluble drugs can be suspended, without the liquid becoming unacceptably viscous. For these reasons, the use of oral suspensions have largely been confined to paediatric medicine, where only a fraction of the adult dose is required.

Attempts to solve the problem of dispersing pharmaceuticals in water have usually involved the use of thickeners (e.g. gums or polymers) to raise the viscosity of the liquid medium, or viscosifiers to make colloidal dispersions. However, such systems are difficult to handle and are often incapable of dispersing relatively coarse particles.