THE EFFECT OF DRY GRANULATION ON THE CONSOLIDATION AND COMPACTION OF CRYSTALLINE LACTOSE

The consolidation and compaction properties of granule fractions prepa red by dry granulation (slugging) of alpha-lactose monohydrate and rol ler dried beta-lactose, respectively, were studied. The results showed that the compactibility of the granule fractions was determined by th e type of lactose used and the granule size. The tablets compacted fro m the granule fractions show a lower compressibility resulting into al most equal crushing strength but a higher specific BET-surface area as compared to the surface area of the slugs. Influence of granule size on tablet strength points to a relation between outside surface area o f granules and tablet strength. Obviously, granule particles sustain t heir integrity to some extent during compaction. Air permeability and mercury porosimetry showed that in tablets with equal strength differe nt pore systems can exist. Generally, tablets compacted from fine gran ule size fractions exhibited finer pore sizes and higher strengths com pared to the tablets compacted from coarse size fractions. Furthermore , mercury porosimetry revealed that the whole pore system determines t ablet strength. This means that granule particles deform during consol idation. The influence of the starting materials on tablet strength ca n not be explained by permeametry surface area measurements and mercur y porosimetry. It is suggested that differences in the internal struct ure between the granules of the two lactose types are responsible.