Modulation of the tabletting behaviour of microcrystalline cellulose pellets by the incorporation of polyethylene glycol.

This study investigated the effect of incorporating a soft material (polyethylene glycol; PEG) into pellets of microcrystalline cellulose (MCC) on the compression behaviour and compactability of the pellets. Low and high porosity MCC pellets were formed. Pellets were also formed from a 1:1 (w/w) mixture of MCC and PEG 6000 to have a porosity equal to that of the low porosity MCC pellets. The degree of compression of the pellets and the porosity, permeability to air and tensile strength of the resulting tablets were determined. Some of the tablets were also deaggregated, and the thickness and porosity of the retrieved pellets were determined. The lowest total tablet porosity was seen with tablets made from pellets containing PEG. The intergranular porosity and the permeability of these tablets were similar to those of tablets made of the high porosity MCC pellets. However, the thickness and porosity of retrieved MCC/PEG pellets were similar to those of the low porosity MCC pellets. The degree of compression levelled off at a lower pressure for the MCC/PEG pellets than for the MCC pellets. Tablet strength values for the MCC/PEG pellets was intermediate between the MCC pellet types and not greatly affected by the applied pressure. It was concluded that the deformation propensity of the pellets was, in general terms, increased due to the presence of the soft material. However, the character of the deformation behaviour changed towards an increased tendency for local deformation during compression, i.e., the ability of adjacent pellet surfaces to conform to each other increased, without marked changes in the main dimensions and porosity of the pellets.