The granulation of binary mixtures: the effects of the properties of the component powders on granules

Sulphanilamide and citric acid individually and in various proportions with lactose, have been granulated by massing and screening. There was an optimum blend, that produced granules of maximum mean size and strength, for each binary system examined. The proportion of the components of this optimal blend was dependent on the physical properties of the second component in a mixture with lactose. Results from three systems, lactose:boric acid, lactose:sulphanilamide and lactose:citric acid indicate that although part dissolution of powder during granulation is a factor affecting granule properties, in some systems other physical properties of the second component may become dominant. It is suggested that the combined effect of cohesiveness and wettability of the powders may make the major contribution to granule strength with the sulphanilamide systems. The ultimate mean granule size produced is determined by the wettability or solubiluty of the powders, or both, in all cases examined. The great affinity of citric acid for aqueous binder solution was the dominant factor determining the properties of granules prepared from lactose:citric acid mixtures.