## 2 Results
Figure 4: Particle size distribution of mixtures prepared with vibrating ball mill. Figure 5: Particle size distribution of granules prepared with pan granularator. Flowability and packing parameters were assessed for the final compression blends of the REF and DT1-DT3 batches (Table 3). All samples demonstrated cohesive flow behavior, with angles of repose above 44\({}^{\circ}\) and compressibility indices greater than 30%, indicating limited flow. However, the vibratory ball mill-treated blends showed slightly higher bulk and tapped densities than the reference, likely due to better packing efficiency achieved by redistribution of fine and coarse particles during mixing. This is consistent with observations for powders behaving according to Geldart Groups A and B.  
Measurements were not conducted for the IT1-IT3 samples, as these were in the form of spherical granules produced by wet granulation. Due to their shape, granules are known to exhibit inherently good flowability, which is one of the primary purposes of the granulation process. This was indirectly confirmed by the low standard deviations observed in the physical characteristics of the resulting tablets. The results obtained for the finished tablets are presented in Figures 6-13. Given that batch-to-batch consistency is a critical parameter in industrial pharmaceutical processes, the graphs show not only the average values for each measured parameter, but also provide separate figures dedicated to standard deviations. These additional plots offer valuable insight into the reproducibility and reliability of each processing method. The magnitude of the standard deviations reflects the stability and uniformity of the formulation process across replicates within the same batch, allowing for a more comprehensive assessment of process robustness. The average tablet mass across all experimental batches is depicted in Figure 6. The dashed line represents the overall target mean of 0.260 g. Batches prepared by direct  
Figure 6: Average tablet mass. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Angle of** & **Angle of** & **Angle of** & **Aerated Bulk** & **Packed Bulk** & \multirow{2}{*}{**Compressibility**} & **Hausner** \\  & **Repose** & **Fall** & **Difference** & **Density** & **Density** & **Ratio** \\  & **[deg]** & **[deg]** & **[deg]** & **[g/cm\({}^{3}\)]** & **[g/cm\({}^{3}\)]** & **[\%]** & **[-]** \\ \hline REF & 44.7 & 17.8 & 26.9 & 0.784 & 1.163 & 32.0 & 1.48 \\ DT1 & 45  
compression using the vibrating ball mill (DT1-DT3) show mass values very close to the target, with DT2 and DT3 slightly exceeding it. In contrast, tablets produced through indirect tableting (IT1-IT3), which includes pan granulation, show consistently lower average mass values, particularly in batches IT2 and IT3. The reference batch (REF), prepared using a conventional V-type mixer, is also slightly below the target value. These observations suggest that direct compression with vibratory mixing ensures more accurate die filling and mass control compared to the granulated series and the reference method. Figure 7 displays the standard deviation of tablet mass for each batch, with a dashed line marking the overall mean SD value of 0.010 g. The REF batch demonstrates the lowest variability, possibly due to low average mass and limited powder cohesion leading to tightly packed tablets. Among the directly compressed tablets, DT2 and DT3 show higher mass variability, likely linked to slight fluctuations in flow behavior despite improved mixing. Notably, the granulated series (IT1-IT3) exhibits lower standard deviations than DT batches, indicating higher batch-to-batch reproducibility and better powder flow achieved through granulation. This highlights the trade-off between process simplicity (direct compression) and performance stability (wet granulation). Figure 8 shows the average thickness of tablets across all production batches, with the overall mean indicated by the dashed line (3.531 mm).