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In search of innovative pharmaceutical (extruder) lines

15.06.2016

Pharmaceutical extrusion poses specific challenges to users that are quite different from those observed in the plastic material processing industry.

In general, extrusion of various kinds of materials involves their ability to flow, a property which substances used as drugs often do not have. To obtain extrusion processing material, it is necessary to create mixtures of ingredients that are active with polymeric media, belonging, in principle, to a group of biopolymers. In this process an important issue is the fact that the active ingredients cannot be subjected to high temperatures, because it would involve the loss of their properties. Due to the fact that the applied pharmaceutical agents require an adequate selection of polymeric media, it should be based on their respective processing parameters. Unfortunately, this procedure entails additional difficulties associated with process sensitivity to even small changes in parameters.

 

There are several types of extruders used in the pharmaceutical industry, including fast-speed or low-speed single-screw extruders or twin-screw extruders. The differences between extruders intended for plastic material and rubber processing and those designed, in the strict sense, for the pharmaceutical industry, are reduced to certain insignificant design solutions and selection and quality of materials, which various device components should be made of, as well as specific documents necessary to manufacture the product in compliance with the principles of Good Manufacturing Practice (GMP).

The pharmaceuticals extrusion process must be characterized by a particularly high level of hygiene and repeatability. Issues related to extrusion in the pharmaceutical industry include:

 

• Detailed, well-developed design of individual elements with respect to their cleaning
• Stainless steel device framework and cylinder cover
• Ground and polished welding joints
• Full calibration and all process parameters documentation
• Gear oils application and greases approved by the Food and Drug Administration (FDA)
• Mercury-free pressure sensors
• Materials in contact with the product are made of stainless steel or nickel-based alloys
• Paints approved by the FDA for the parts which cannot be made of stainless steel (gearbox)
• Validated Programmable Logic Controller (PLC) [1].

Polymeric materials processing by means of extruders is associated with performing such unit operations as dispensing, melting, mixing, degassing, and pumping, while in the case of pharmaceutical substances the treatment processes are generally more complex. Namely, they include a number of different stages of component processing, e.g. media dispensing, partial melting and mixing, degassing volatile substances, active and inert ingredients dispensing, mixing ingredients, removing gases for purification, degassing under high vacuum, unloading and compaction [1].

Building a line intended for the pharmaceutical industry (extruders and associated accessories - granulator, pelletizer, cooling belt, etc.) in accordance to desired properties also requires proper (sophisticated) design of individual extruder components, i.e. screws, cylinder, nozzle, and the use of additional auxiliary devices. A separate issue is demanding implementation procedure of the finished product to market and its commissioning.

On the basis of the above, it can be concluded that delivering to the Client a device that meets complex pharmaceutical industry requirements is a task requiring broad interdisciplinary knowledge and many years of experience in the design and construction of extruders, which Zamak Mercator possesses.

 

References

[1] M. Charles, I. Ghebre-Sellassie, Pharmaceutical Extrusion Technology, 2003

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