THE RELATIONSHIP BETWEEN BULK-DENSITY AND COMPACTIBILITY OF LACTOSE GRANULATIONS

The relationship between the bulk density and the compactibility of la ctose granulations was studied. The granulations were prepared from di fferent alpha-lactose monohydrate and roller dried beta-lactose powder s by wet granulation, using different techniques with only water as a binder, or by slugging. The results demonstrate that by the process of granulation of one lactose powder, granules with different bulk densi ties and different compactibilities can be prepared. In addition to th e type of lactose used, the compactibility of the granule fractions is dependent on the bulk density of the granule fraction. Generally, wit h an increase of the bulk density, the compactibility of a granule fra ction decreases. Little variation is observed between the intergranula r porosities of the granule fractions. More differences are found betw een the intragranular porosities of the granule fractions. However, th e compactibility of granule fractions of one lactose type is mainly de termined by the total porosity of the granule powder bed. Mercury poro simetry determinations on tablets compacted from the granule fractions show a relationship between the tablet pore system and the compact st rength: compression of granulations with a low bulk density results in to tablets with a small average pore diameter and a high crushing stre ngth. Obviously, the possibility to deform a granule fraction during c ompression, the deformation potential, is determined by the total poro sity of the powder bed. A high deformation potential, i.e., a high com pactibility, can be obtained by using a granulation procedure in which granulations with a low bulk density are produced.