Pellets are small, spherical particulates with a narrow size distribution, which have many advantages over other pharmaceutical forms.
The purpose of the master thesis was to study the influence of the extrusion and spheronization parameters on the properties of the extrudates and pellets, prepared with extrusion and spheronization. In further, we determined how the thickness and diameter of the spheronization plate openings influenced the physical properties of the extrudate such as moisture content, density and mechanical characteristics. We have demonstrated that using of a thicker spheronitation plate more compact and plastic extrudates were formed. These findings are in accordance with the higher plasticity of extrudes (lower tensile strengt and Young's modulus). The next step was shperonization of the extrudates. The size and the distribution of the pellets were determined by image-analysis so called PATVIS APA technology. In addition, the size distribution of pellets was also evaluated by sieve analysis, and the surface was visualized using the optical and SEM microscopes. We have established that the properties of the spheronization plate are more important for the size and distribution of the pellets, and spheronization parameters are crucial for their shape. A larger proportion of oversized pellets was obtained by using a thicker plate with larger openings, since the extrudate is more compact and during spheronization process breaks into larger and more evenly distributes particles, which need a longer time and higher spheronizer speed for adequate pellet's sphericity. Using a thinner plate, we obtained a brittle extrudate that was fragmenting to smaller particles during the spheronization process (e.g. at high spheronization speed, the proportion of the dust fraction was significatntly higher). Due to the agglomeration of the dust particles, a wider distribution of the pellet size was also obtained. The best yield (the highest proportion of pellets with size between 0,71 to 1,12 mm) was obtained using the thickest matrix (4 mm) and the smallest opening diameter (0,7 mm). For the spherical shape of the pellets, the spheronization time and spheronizer speed are important, which must be optimally determined.
We have shown that the extrusion and ball parameters must be adapted according to the physico-chemical properties of the ingredients, extruders and equipment.