Twin-Screw Extruders for Pharmaceutical Products from a Technical and Historical Perspective
The twin-screw extruder (TSE) dominate the market for continuous mixing and devolatilization, and single-screw extruders (SSE) high-pressure pumping for the extrusion of parts such as film, sheet, profiles, tubes, fibers, and coatings. Interestingly, in terms of the number of units currently installed each year, there are approximately ten times as many SSEs compared to TSEs, implying there are still opportunities for usage of SSEs for therapeutic drug delivery systems, particularly for multifunctional medical devices. The most widely used for the plastics and pharmaceutical industries is the high-speed energy input corotating, intermeshing TSE. Counterrotating intermeshing twin screw extruders are available in either the high-speed energy input configuration or in a low-speed late-fusing format. If the old saying "the best indication of future performance is past performance" holds true, then the future for twin-screw extrusion to develop and manufacture dosage forms will eventually dominate the pharmaceutical manufacturing landscape for new drug entities.