Downscaling of the tableting process: Feasibility of miniaturized forced feeders on a high-speed rotary tablet press

With the current transformation of the pharmaceutical industry towards continuous manufacturing, there is an inherent need to embrace this concept already during the early stages of drug formulation. Therefore, this research paper investigated the feasibility of using miniaturized forced feeders on a high-speed rotary tablet press with the intention of downscaling the tableting process. Forced feeders with a reduced volume (up to 46% compared to the conventional two-compartment forced feeder) were designed by either sealing one compartment (i.e. R&D1) or lowering of the compartment height (i.e. R&D2). These feed frame designs were thoroughly analysed in combination with two paddle types over a wide range of process-settings (i.e. tableting speed, paddle speed, direction of paddle rotation, overfill-level). A poorly flowing model powder (i.e. MCC 101) was deliberately selected as challenging formulation. Empirical modelling of feed frame R&D1 revealed a positive impact on the die-filling variability when the radial curved cuboid paddles rotated in counterclockwise direction at high paddle speed. Moreover, a strong resemblance between the R&D2 feed frame and the conventional forced feeder was observed during multivariate data analysis, indicating that this miniaturized type could be used during downscaling studies of the conventional tableting process. The potential of this forced feeder was acknowledged by the similar trends in die-filling variability with respect to varying process settings, when a design-of-experiments (DOE) was performing including feed frame type as a qualitative factor. Overall, it was concluded that both types of miniaturized forced feeders can be used on a high-speed rotary tablet press when lower material consumption rates are desired while the R&D2 feed frame bears the highest predictability regarding the die-filling uniformity in the conventional larger two-compartment forced feeder.