Effect of intragranular and extragranular disintegrating agents on particle size of disintegrated tablets

Five materials were compared for their effectiveness as disintegrating agents: maize starch, sodium calcium alginate, alginic acid, microcrystalline cellulose, and a colloidal aluminum silicate. The effect of the proportion of the agent present and the position with respect to the granule, intra- and extragranular, was examined. The extragranular formulations disintegrated much more rapidly than the intragranular ones, but the latter gave a much finer dispersion of particles. A combination of intra- and extragranular disintegrating agents gave the best compromise; of those tested, the alginates appeared to effect the breakdown to the smallest particles when placed intragranularly. A method of assessing the effectiveness of disintegrating agents for uncoated tablets is suggested, but the resulting weight mean particle size is the more important criterion for tablets complying with a pharmacopoeial disintegration test. The porosity and crushing strength of tablets are useful as guides to disintegration only when a given formulation is used.