The influence of granule density on granule strength and resulting compact strength

Unit operations are generally considered as separate pieces of the manufacturing processing line. This work investigated the link between high shear granulation and tablet compression.More specifically, the objective of this study was to quantitatively investigate the influence of granule density on granule strength and compact strength. Parametric high-shear wet granulations were conducted according to impeller speed, quantity of water and wet massing time resulting in granules with varying physical attributes. Upon characterizing the granule density, the purpose of confined uni-axial compression tests was two-fold, to determine the compressive strength of the granules and to prepare compacts for further mechanical testing. Compact hardness was determined using indirect tensile testing, the results of which were used to derive the compact tensile strength.Granule compressive strength was modeled to granule density through the exponential Duckworth strength–density model. This relationship held true for granule density prepared by different methods, suggesting that the method of manufacture may not influence the granule strength–granule density relationship. Compact tensile strength was well described by an inverse power law relationship of the extracted granule strength. Although empirically derived, this finding provides insight into the mechanism of strength development during granule compaction. Overall, this work justifies further research into controlling granule density during processing to ensure acceptable and reproducible compaction performance during tablet compression.

graphical abstractImpact of granule strength on compact strength and product.Figure optionsDownload high-quality image (93 K)Download as PowerPoint slideHighlights
► Desired compaction properties can be obtained by controlling granule density.
► Illustrates path independence of manufacturing pathway.
► Supports transition from time based system.
► Possible to monitor the process of densification during granulation to evaluate compact performance.