Comparison of granule strength and tablet tensile strength

The granule strength (crushing load) of lactose granulated with 1-9% povidone was measured initially and at intervals during a 1-year period. The granule strengths of dibasic calcium phosphate dihydrate granulated with various concentrations of starch and povidone were measured. The axial and radial tensile strengths of tablets compressed from these granules were determined and related to concentration of binder and granule strength. The effect of compressional force on the integrity of granules in a tablet matrix is shown in scanning electron photomicrographs of the fractured tablets which had undergone a diametral compression test. It appears that the compressional force and the concentration of binder contribute more than granule strength to tablet tensile strength.