Compression characteristics of granulated materials. VII. The effect of intragranular binder distribution on the compatibility of some lactose granulations.

Two sets of lactose-polyvinylpyrrolidone granulations (95:5) of different intragranular binder distributions were produced. The intragranular binder distribution was controlled by a two-step granulation procedure. The compactibility as well as the volume reduction behavior of the granulations was evaluated. Granulations with a more homogeneous distribution of binder in the granules generally produced tablets of a higher mechanical strength than granulations with a peripheral localization of binder. The tablet strength of the latter granulations was also comparatively more reduced by the addition of magnesium stearate. Thus, it is suggested that high granule porosity in combination with homogeneous intragranular binder distribution is advantageous for the compactibility of a granulation. The results of this study therefore contradict earlier suggestions in the literature regarding the preferred intragranular binder distribution.