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Agglomeration behavior of a twin-screw extruder at different material throughputs was investigated. Water insoluble dicalcium phosphate and the binder povidone were agglomerated with demineralized water with five different screw configurations using conveying-, kneading- or combing mixer elements. Increasing material throughput mainly had an effect on the particle size of granules. Due to a higher filling degree of the barrel, the particle size was higher at increased material throughput. Granule porosity was generally influenced by screw element type. With a higher element dispersivity granule porosity and friability decreased. Compression of the different granule batches led to comparable tablet properties. A simple scale up in order to increase batch size can be realized by increasing either production time at given material throughput or material throughput.

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Abstract. Coating of solid dosage forms is an important unit operation in the pharmaceutical industry. In recent years, numerical simulations of drug manufacturing processes have been gaining interest as process analytical technology tools. The discrete element method (DEM) in particular is suitable to model tabletcoating processes. For the development of accurate simulations, information on the material properties of the tablets is required. In this study, the mechanical parameters Young's modulus, coefficient of restitution (CoR), and coefficients of friction (CoF) of gastrointestinal therapeutic systems (GITS) and of activecoated GITS were measured experimentally. The dynamic angle of repose of these tablets in a drum coater was investigated to revise the CoF. The resulting values were used as input data in DEM simulations to compare simulation and experiment. A mean value of Young's modulus of 31.9 MPa was determined by the uniaxial compression test. The CoR was found to be 0.78. For both tablet-steel and tablet-tablet friction, active-coated GITS showed a higher CoF compared with GITS. According to the values of the dynamic angle of repose, the CoF was adjusted to obtain consistent tablet motion in the simulation and in the experiment. On the basis of this experimental characterization, mechanical parameters are integrated into DEM simulation programs to perform numerical analysis of coating processes.

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