High shear granulation of crystalline sugars

Sugars can be used in granulation processes with different purposes: as diluents, binders, taste masking agents, sweeteners and agents for drug controlled release (e.g. sugar beads). They are soluble and sticky excipients and their processing in high shear granulators may be difficult: they can easily adhere to mixer walls or lead to uncontrolled granule growth. The purpose of this research was to evaluate the different behaviour in high shear wet granulation of four selected sugars: mannitol, sorbitol, xylitol and sucrose (size range of 60-300 μm). They were characterized by flowability and 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 changes in the solid state of the sugars but caused a reduction in flowability that was stronger in the case of sorbitol and xylitol. Powder flowability showed correlation to hygroscopicity but not to the final thickening of dissolved sugars. Granulation experiments demonstrated the feasibility of the process with the selected sugars and the possibility to predict the amount of water necessary to the process through mixer torque rheometer measurements.