Boutell, Suzanne Louise; (1995) Factors influencing the preparation of spherical granules by extrusion/spheronisation. Doctoral thesis (Ph.D.), University College London (United Kingdom).

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Abstract

Pelletization has many advantages over other dosage forms and one of the methods available for producing these systems is the process of extrusion and spheronisation. Although a great deal of information has been published relating to the process of extrusion and spheronisation, the effects of changing the formulation, in terms of the liquid binder and the dry powder characteristics, has on the extrusion profile and the final end product, especially on the shape, size, density and porosity has not been fully investigated. Materials were initially characterized in terms of their hydrophilicity/hydrophobicity, surface tension and viscosity. A pressure membrane apparatus was used to investigate a materials powder bed structure and how, by altering the liquid properties, the movement of liquid through the pore structure within the powder bed was affected. Different ratios of barium sulphate to Avicel PH101, with differing liquid binders and liquid contents was studied in terms of the extrusion profile and liquid movement during the extrusion process. From this it was possible to show how the surface tension, viscosity and the quantity of liquid affected the movement of liquid during the extrusion process and the consequences it had on the final end products in terms of shape, size, density and porosity. Also, the influence of adding glycerol monostearate (a hydrophobic material) to a predominantly hydrophilic system was investigated especially on the extrusion profile and the end product characteristics. Rheological characterizadon of the various mixtures, using a capillary rheometer and a controlled stress rheometer, was used to study the influence of the moisture content and the presence of glycerol monostearate had on various ratios of barium sulphate to Avicel PH101 formuladons in order to predict whether a mixture would be able to produce good granules.

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