Comparative Tableting Properties of Sixteen Microcrystalline Celluloses

The tableting characteristics of sixteen NF grade microcrystalline celluloses produced by seven manufacturers were investigated. Nine samples were type 1 celluloses (fine powders) and seven corresponded to type 2 celluloses (coarse powders). Some samples were second batches of the same products. The powders were examined for their moisture content, particle-size distribution, for their true, bulk and tap densities and for their flow properties. The effect of adding a lubricant with a low friction coefficient (0.5% magnesium stearate) on the packing and flow properties was evaluated.Basic compression studies were made on an instrumented eccentric tableting machine at an axial pressure of 100 MPa. The work of compression and the elastic recovery of the compacts were determined, as well as many friction parameters. The tabletability of the powders was assessed by measuring the diametral crushing force of the compacts.In a second set of experiment, we examined the effect on the compactability of the powders of adding 0.5% magnesium stearate.Weight variations of lubricated tablets were studied on a high speed rotary machine. In these runs, the force required to prepare tablets of a given mechanical strength was monitored. The uniformity of dimensions, the friability and the disintegration time of the tablets were also checked.Great differences in packing and tableting properties and in sensitivity to the addition of a lubricant were generally observed between products from the various manufacturers. In contrast, lot-to-lot variability was quite acceptable.