Analytical methods for characterising the functional performance of tablet formulations

Besides API dissolution, the processes of wetting, water uptake, swelling, disintegration and dispersion are characteristics of the functional performance of tablets. In this study, the functional performance of tablets of pure pharmaceutical polymers and related multi-component formulations is investigated by quantitative evaluation of its characteristics. Wetting of pure polymer tablets is analysed by contact angle measurement. A new experimental set-up for the simultaneous and time-resolved determination of water uptake and swelling of tablets is developed, validated and applied. The impact of different tablet formulation properties, e. g. polymer type and particle size, additional excipients, such as fillers, disintegrants and lubricants, tablet porosity, as well as the pH of the test medium is investigated. Furthermore, an empirical model is introduced depicting the experimental results of water uptake and swelling with four characteristic parameters. Disintegration and dispersion are characterised by another newly developed analytical method, where the disintegration time is assessed and a time-resolved size analysis of the disintegrated fragments of the tablets is performed within a flow channel. In addition, the disintegration time of the tablets is determined by a conventional disintegration tester and the results are compared with those of the newly developed technique. By variation of the fluid velocity, the influence of the hydrodynamic conditions on tablet disintegration and dispersion is investigated and a potential relation to the in vivo conditions is discussed. Moreover, the impact of different tablet formulation properties, e. g. polymer type, disintegrants and tablet porosity is investigated.