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Effect of pellet size on degree of deformation and densification during compression and on compactability of microcrystalline cellulose pellets

1998; Elsevier BV; Volume: 163; Issue: 1-2 Linguagem: Inglês

10.1016/s0378-5173(97)00355-4

1873-3476

Barbro Johansson, Fredrik Nicklasson, Göran Alderborn,

Advanced Drug Delivery Systems

Microcrystalline cellulose pellets (size fractions 425–500 and 1250–1400 μm, porosity 38%) were prepared and compacted. The porosity and tensile strength of tablets of unlubricated pellets were determined. Tablets of lubricated pellets were deaggregated and the porosity and the main dimensions of the retrieved pellets were measured. The dominating mechanisms of compression for the pellets were deformation and densification. The original size of the pellets did not affect the volume or porosity changes of the tablet with tablet formation pressure. Consequently, the degree of densification of individual pellets, which occured during compression, was independent of the original pellet size. However, the degree of deformation of individual pellets during compression was higher for larger pellets. There was thus a different dependence of pellet size for the dominating mechanisms of compression for this type of aggregates. An explanation for this is that deformation is a phenomenon related to the force distribution in the pellet bed during compression, while densification is related to the total stress applied to the pellet bed during compression. The results obtained in this study have also shown that the compactability of pellets at moderate applied pressures was independent of the original pellet size, but at 160 MPa, the larger pellets formed tablets of a slightly higher tensile strength.