## 2 Results
Tablets from the direct compression series (DT1-DT3) tend to be slightly thicker than the reference (REF) and granulated (IT1-IT3) batches, with DT2 and DT3 reaching the highest average values. These variations may result from differences in powder compressibility and die fill dynamics. Tablets from the indirect tableting process exhibit more uniform thicknesses and are closer to the overall mean. Figure 9 presents the standard deviation of tablet thickness, providing insight into the consistency of tablet dimensions within each batch. The reference batch (REF) shows the highest variability, suggesting poor uniformity in die filling. The granulated batches (IT1-IT3) display notably lower standard deviations, indicating greater dimensional consistency due to improved flow and packing behavior of granules. Among the directly compressed batches, DT2 and DT3 demonstrate moderate variability, with DT1 achieving uniformity comparable to the IT series. Figure 7: Standard deviation of tablet mass. Figure 10 presents the average tablet abrasiveness, a critical quality parameter reflecting the mechanical resistance of tablets to surface damage during handling. The REF batch demonstrates excessively high abrasiveness (over 7%), far exceeding the acceptable threshold and the overall mean value of 1.613%. In contrast, all experimental batches (DT and IT series) show significantly reduced abrasiveness, with values well below 2%, indicating enhanced tablet integrity. This suggests that both direct compression (with vibratory mixing) and wet granulation considerably improve mechanical robustness. Figure 11 illustrates the standard deviation of tablet abrasiveness, further highlighting batch-to-batch variability. The REF batch again shows the highest inconsistency, followed by DT1. Batches DT2 and DT3 display low variability, suggesting stable processing conditions after extended mixing. Among the granulated batches, IT2 and IT3 show slightly higher variability compared to IT1 but remain within an acceptable range. Overall, granulation contributes to higher reproducibility in mechanical performance, while direct compression with appropriate mixing time (DT3) can yield similarly robust and consistent tablets. Figure 1:0 Average tablet thickness. Figure 1:1 Standard deviation of tablet thickness. The results of API content analysis reveal distinct differences in both average values and variability across the tested batches (Figures 12 and 13). The reference batch (REF) and DT1 (direct compression with shortest mixing time) exhibit the highest average API content, but also the greatest standard deviations, indicating poor homogeneity and significant variation between individual tablets. This is likely due to insufficient mixing and uneven distribution of the active substance in the bulk powder, especially in the absence of granulation or adequate blending time. In contrast, DT2 and IT2 demonstrate the lowest standard deviations, suggesting high uniformity of drug distribution within the batch. For DT2, this result highlights the effectiveness of vibratory ball mill mixing with optimized process duration (5 min) in achieving homogenous blends. Similarly, IT2 benefits from the improved granule formation at the optimal pan inclination angle (30\({}^{\circ}\)), enhancing blend uniformity and die filling consistency. Figure 1:2 Standard deviation of tablet abrasiveness. Figure 1:3 Average tablet abrasiveness. Notably, the indirect tableting batches IT1, IT2, and IT3 exhibit very similar average API content, which confirms the reliability and reproducibility of the granulation-based process. This consistency is particularly valuable in industrial settings, where regulatory compliance requires tight control over dosage uniformity. These findings emphasize the importance of both mixing intensity and granulation conditions in achieving uniform API distribution, and further support the vibratory ball mill as a promising alternative to conventional granulation under optimized parameters.