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Influence of Rotational Speed and Surface of Rotating Disc on Pellets Produced by Direct Rotor Pelletization

Robert Pis¡ek, Odon Planins¡ek, Matjaz¡ Tus, and Stane Src¡ic

University of Ljubljana, Faculty of Pharmacy, Ljubljana (Slovenia)

The aim of this research work was to investigate the influence of disc surface and its speed on the direct pelletization with rotor technology. Rotor technology is “single pot” method of pellet production based on fluid bed technology. Two series of experiments have been carried out on GPCG 1 (Glatt Powder Coater Granulator) fluid bed apparatus. In the first series of the experiments mixture of 350 g of pentoxifylline and 150 g microcrystalline cellulose were used for pellets production. In the second series of experiments, the same amount of ketoprofen was used instead of pentoxifylline. In both series suspension of EudragitâNE 30 D was used as liquid binder but in each series at different concentration. Within each series of experiments the process variables were kept constant within limitations of the process, except rotational speed of the disc during agglomeration and spheronization step. Additionally, two different rotating disc were used; one with smooth and the other with textured surface. The results show that both surface and rotational speed of the disc have influence on shape, surface and size of pellets while there is less effect on true density, humidity content and yield of the experiment. Keeping rotational speed of the smooth disc constant during agglomeration of powder particles and increasing rotational speed during spheronization of agglomerates results in more spherical pellets with larger diameters and smoother surfaces. The influence of rotating disc with textured surface is opposite to the previously mentioned influence of smooth disc. Increasing rotational speed during spheronization step at the constant speed during agglomeration step results in smaller and less spherical pellets with rougher surface.

Key words Direct rotor pelletization, disc surface, rotational speed · Fluid bed technology · Microcrystalline cellulose · Pellets, single-pot production