Evaluation and characterization of disintegrants through dilatometric and calorimetric methods

The evaluation of some disintegrants widely used in pharmaceutical formulations (sodium carboxymethylstarch, sodium carboxymethylcellulose, polyvinylpyrrolidone) and of a new candidate disintegrant (a polymeric derivative of β-cyclodextrin) is reported. Dilatometric and calorimetric measurements have been performed on powdered samples of these materials by water addition, in order to trace a comprehensive profile of the intrinsic properties of these materials, to elucidate the relevant mechanisms of interaction with water, and to outline the possible correlations between these parameters and the performance of the excipients tested. These results have been compared with data obtained by water uptake, sedimentation volume, and hydration capacity determinations. Calorimetric measurements allowed the interpretation of the mechanism of interaction with water in terms of two distinct contributions: heat of wetting and heat of swelling.