Hot-melt extrusion (HME) using twin-screw extruders (TSEs) is
increasingly being used to make solid dispersions of drugs in a
polymer matrix. The process is useful for poorly soluble drugs
and for alternative dosage forms such as controlled-release drug
devices. Small, benchtop TSEs are available for formulation
development, but these are typically not appropriate for process
development. Mid-size TSEs, however, can be used for process
development and scale-up. In the past, laboratories had only
small-scale batch mixers for formulation development, but during
the past few years, several extruder manufacturers have
introduced laboratory-scale TSEs suitable for API quantities as
small as 5–20 g, thus enabling pharmaceutical manufacturers to
test new drug candidates on a TSE. A TSE has shorter residence
time and exposes the material to lower thermal stress than a
small-scale batch mixer, notes Andrew Loxley, director of new
technologies at Particle Sciences, a company providing drug-
development services. Particl