HIGH SHEAR GRANULATION PROCESS USING CRYSTALLINE SUGARS

Sugars can be used in the granulation process with different purposes. In particular, they can act as diluents, binders but also as taste masking agents, sweeteners and agents for drug controlled release (e.g. sugar beads). Sugars are soluble and sticky excipients [1,2] and their manipulation in high shear granulators may be very difficult because they can adhere to the mixer walls or lead to an uncontrolled granule growth. The purpose of this research was to evaluate the different behaviours in high shear wet granulation of four selected sugars: mannitol, sorbitol, xylitol and sucrose in the size range of 60-300 µm. In order to investigate the mechanism of their agglomeration the four sugars were initially characterized by viscosity measurements and their solid state was studied by X-ray diffraction. Also the hygroscopicity was evaluated by conditioning powders at different relative humidity (RH 65 and 80%). Results highlighted that the humidity uptake did not produce any change in the solid state of the sugars. In order to predict the optimal amount of water required for the high shear granulation, mixtures composed of 25% (w/w) of microcrystalline cellulose and 75% (w/w) of sugar were analyzed with a mixer torque rheometer [3]. Granulation experiments demonstrated not only the feasibility of the process with the selected sugars but also the possibility to predict the amount of water necessary to the process through the mixer torque rheometer. Data also showed the effect of higher thickening power on the reduction of the water required for the granulation.