Influence of porosity and formula solubility on disintegrant efficiency in tablets

Water uptake and disintegrating force development are well recognized in the literature as being responsible for tablet disintegration. In a previous work, the study of the relationships between the amount of water taken up and the force developed in tablets enabled us to quantify the capability of a disintegrant to effectively transform water taken up into disintegrating force. This capability was expressed as the 'force equivalent' of a given amount of water. In the present work, simultaneous measurements of water uptake and force development were carried out on model tablets prepared at different compression forces, based on materials of differing solubility and containing a fixed amount of the same disintegrant. The influence of porosity and formula solubility on the 'force equivalent' parameter was assessed: in particular, 'force equivalent' was found to be directly proportional to percentage porosity and mean pore diameter, and inversely related to pore surface area. Moreover, the comparison of the 'force equivalent' obtained for tablets of similar porosity but different solubility showed that a higher value of 'force equivalent' is to be expected when the tablet base material is insoluble in water.