## 2 Results
The granules produced at 10\({}^{\circ}\) (IT3) were insufficiently developed, whereas excessive tilt at 50\({}^{\circ}\) (IT1) led to particle segregation and less consistent compaction. Figure 1 illustrates the process of direct tableting, in which all components of the formulation--sodium naproxen (API), dolomite and cellulose (fillers), polyvinylpyrrolidone (binder), and magnesium stearate (lubricant)--are dry-blended in a mixer. The homogeneous powder mixture is then fed directly into a tablet press for compression. This method eliminates the need for a granulation step, reducing the number of operations and processing time. Figure 2 shows the process of indirect tableting, which incorporates a wet granulation stage. After initial mixing of the raw materials, a binder solution is added--typically water in combination with air atomization--to form granules in a granulator. The granulated material is then dried, sieved if needed, and fed into the tablet press. This approach improves powder flow and compressibility, especially beneficial when processing formulations containing cohesive or poorly compactable ingredients. Figure 1: Schematic representation of the direct tableting process, in which powder components are blended and directly compressed without prior granulation. The particle size distribution of the individual raw materials used in the formulation is shown in Figure 3. The curves reveal distinct differences in particle size profiles among the components. Magnesium stearate exhibits the narrowest distribution and the finest particles, with a dominant fraction below 50 \(\upmu\)m. Sodium naproxen and cellulose display broader distributions, peaking around 100-200 \(\upmu\)m, while dolomite is characterized by a wider spread, with a significant fraction of particles above 200 \(\upmu\)m, reflecting its more heterogeneous structure. These differences in particle size and distribution are expected to influence both powder flowability and blend homogeneity during processing. The particle size distribution of polyvinylpyrrolidone (PVP) was not experimentally determined in this study due to its high solubility in a wide range of liquids, including those commonly used as dispersants in wet measurement systems. Laser diffraction analysis was conducted using a wet dispersion unit, which precluded accurate assessment of PVP particle size. According to the manufacturer's specifications, the average particle size of the PVP used in the formulation is approximately 20 \(\upmu\)m.  
Figure 3: Particle size distribution of raw materials. Figure 2: Schematic representation of the indirect tableting process including wet granulation, where the blended powder is granulated before compression. Figure 4 shows the particle size distribution of powder blends prepared by vibratory ball mill mixing at three different mixing times: 2.5, 5, and 10 min. As the mixing time increases, a noticeable shift of the distribution towards larger particle sizes is observed, along with peak broadening. This suggests a tendency for particle agglomeration or mechanical fusion during prolonged vibration. The most intensive mixing (10 min) produces a broader distribution with a reduced proportion of fine particles, indicating more cohesive interactions and possible granule formation effects. These trends can significantly affect downstream processability, particularly in direct compression. Among the granulated batches, granule size was found to correlate with the pan inclination angle used during the granulation process. Batch IT3, prepared at the highest angle of inclination (50\({}^{\circ}\)), produced the largest granules, followed by IT2 at 30\({}^{\circ}\), and IT1 at the lowest angle (10\({}^{\circ}\)), which resulted in the smallest particle size (Figure 5). The corresponding initial moisture content of the wet granules was 18.5% for IT1, 16.8% for IT2, and 14.8% for IT3. Each batch was dried to achieve a residual moisture content below 1%, a level shown to provide optimal conditions for subsequent tablet compression.