Compression force/time-profiles of microcrystalline cellulose, dicalcium phosphate dihydrate and their binary mixtures-a critical consideration of experimental parameters

Compression force/time-profiles of microcrystalline cellulose and dicalcium phosphate dihydrate and mixtures thereof were compared on a modern rotary press by three different methods of compression: compression to a constant tablet weight, compression to a constant tablet height and compression from a constant filling depth. Compression was carried out at three different compression force levels. The differences obtained by analysing the area under the curve in the compression, dwell and decompression phase could be explained by differences of the in-die working density of the powders and their respective compression behaviour. From data of the compression phase as well as from the area-quotient-index obtained from the dwell time it was possible to estimate the percolation threshold of dicalcium phosphate dihydrate in a mixture with microcrystalline cellulose to ˜ 50% (w/w) corresponding to 30% (v/v).