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L. B. Bohle Maschinen + Verfahren GmbH

More solid despite less liquid

Tuesday, 13 September 2011


ENNIGERLOH (DE) – Prof. Klaus-Jürgen Steffens of Bonn University has tested the new extruder from L.B. Bohle Maschinen + Verfahren GmbH.

Professor, you have already carried out a number of tests with the BCG (Bohle Conti Granulator). Please explain to us the basic operation method of the system.

The core of the system is a newly designed GMP-compliant twin-screw extruder, which is supplied by a continuous mass-controlled powder dosing unit and a continuous liquid dosing unit. The finished granulate falls directly into the continuous rotating vacuum contact dryer, without requiring transport. The dryer operates with an innovative blending and dispersing unit to reliably prevent the wet granulate caking to any surface. The final granulate size is then adjusted using the well known Bohle BTS Turbo Sieve.

Which tests have you carried out with the system so far?

We have carried out tests with substances that are difficult to granulate, such as Paracetamol and Ibuprofen at a high dosage of 75% active concentration. We have made comparisons with highshear granulation, tested various binding agents as well as the impact of different screw configurations. Our targets were always the properties of the tablets produced from the granulates, such as strength (format-independent as 'tensile strength'), disintegration and substance release.

What are the benefits of the Bohle system in your opinion?

Compared to other extruders the BCG extruder is characterized by the typical Bohle GMP design. The monoblock design features no gaps or connections which make it easy to install and clean. The 'real' torque measurement ' separately on each screw ' is particularly noteworthy, allowing outstanding control of the process. This is another step forward in implementing Process Analytical Technology. Last but not least, the new continuous rotating vacuum dryer of the BCG system features significant advantages vs. other systems.

What do you make of other solutions available on the market? For instance, common features / differences compared to Bohle solutions?

So far, a number of tests for continuous wet granulation have been carried out, such as the continuous fluid bed system or the semi-continuous process utilizing very small pulsed batches. They have not taken hold on the market for wet granulates because of their low shearing force and complicated, failure-prone transport systems. Extrusion, however, is a promising solution. During granulation the shearing forces can be significantly better tuned to the product properties than in any other process.

What are the future trends in pharmaceutical production?

The pharmaceutical market will be dominated by dualism. On the one hand, we will have innovative and expensive pharmaceuticals which will be produced in relatively small batches and for which the production costs will be less important. In contrast, we have been observing global cost pressure and a high concentration of manufacturers on the constantly growing generic drug market. This will result in a greater market share for cost-cutting continuous production systems. It is therefore vital that the control and machine technology of the systems are state-of-the-art to ensure elegant and enhanced failure-free production.

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