THE INFLUENCE OF MOISTURE-CONTENT ON THE PREPARATION OF SPHERICAL GRANULES OF BARIUM-SULFATE AND MICROCRYSTALLINE CELLULOSE

The influence of water content on the ability of mixtures of a range of proportions of barium sulphate and microcrystalline cellulose to form spherical granules by extrusion spheronisation has been assessed. Producing the extrudate by a ram extruder indicates that a range of steady state extrusion forces, which produce a satisfactory product, can be assigned to formulations. Below 2500 N, the extrudate is too wet and agglomerates, while above 10 000 N the product is too dry and fails to round or cohere. The range of moisture contents over which successful products can be prepared is relatively wide for contents of barium sulphate from 20 to 60%. As this level is exceeded, the moisture content becomes more critical and once 80% of barium sulphate is reached, a critical moisture content is required. The quantity of water relative to the microcrystalline cellulose content, which was required to produce a consistent product in terms of particle size, was found to be proportional to the percentage of barium sulphate in the mixture. The ratio ranged from 1:1 for 20% barium sulphate to 1:1.5 for 80% barium sulphate.