Use of Hot Melt Extrusion in Life Sciences Explored at Coperion Congress

The benefits of hot-melt extrusion in pharmaceutical and medical applications took centre stage on 15 April, when equipment builder Coperion held an in-house “congress” at its facility in Stuttgart, Germany. Approximately 100 guests from the pharmaceutical industry attended the event, which provided an overview of what the company describes as a rapidly growing application of hot melt extrusion technology with a demonstration of the company’s pharmaceutical version of its ZSK twin-screw compounder.Coperion (formerly Werner & Pfleiderer) counts itself among the pioneers of hot melt extrusion. Its ZSK compounders are used for the continuous production of tablet mixtures, transdermal patches with active ingredients and adhesives for medical devices such as ostomy bags, notes the company in a press release issued after the event. Other applications for hot melt extrusion include the manufacture of medical compounds with delayed ingredient release, the processing of insoluble substances or substances that are more difficult to dissolve, encapsulation and taste masking.

The star of the show, so to speak, was the Coperion ZSK MEGAcompounder PLUS for pharmaceutical and medical applications. The system is self-cleaning and has virtually no dead spots, and all parts that come in contact with the product are manufactured from proven materials with specially treated surfaces. Only US FDA–approved oils and lubricants are used. In addition, the extruder meets the stringent workplace safety requirements of the pharmaceutical industry. Congress participants were able to gain a practical impression of these special features during a demonstration of hot melt extrusion in Coperion’s test lab. Organic pigments from Rudolf Wild GmbH & Co. KG were worked into a Soluplus matrix polymer from BASF.

The technology of hot melt extrusion

Hot melt extrusion technology mixes active pharmaceutical ingredients (APIs) into a matrix. The APIs, the matrix substances and the additives are fed continuously in precise quantities by means of gravimetric feeding systems into the process section of the extruder, where they are melted with the aid of the co-rotating twin screws and then gently mixed and homogenised at a low temperature in a matter of seconds.  The screw shafts of the ZSK MEGAcompounder PLUS feature different, process-optimised screw flights for each extruder zone. If required, further solid or liquid substances can be fed into the extruder barrel via lateral feeding devices. A vacuum venting system can be installed upstream of the discharge section to release trapped air, volatiles and/or solvents and, thus, obtain a bubble-free melt. The finished compound can then be directly extruded and made into pellets via an extrusion die plate or further processed in a downstream calender.

Advantages of hot melt extrusion in pharmaceutical applications

Compared with conventional processes, continuous hot melt extrusion affords the manufacturer a several advantages, according to Coperion:

• Substances that are insoluble or difficult to dissolve in water are compounded into a matrix with a stable and uniform dispersion profile.
• API content is increased as is the bioavailability of the APIs.
• Because it is a solvent-free process, some production stages such as drying are eliminated.
• Homogeneity is ensured, and the short residence time and low operating temperature ensure gentle compounding.
• The process is suitable for the production of medical masses with tailored or delayed release systems.

Tags: coperion, hot melt extrusion