Studies on the Granulation Process of Granules for Tableting with a High Speed Mixer. II. Influence of Particle Size of Active Substance on Granulation.

Abstract

In the process of granulation for tableting using theophylline as a model drug, the power consumption pattern and the physical properties of the granules were examined with varied particle sizes of theophylline. During kneading of the physical mixtures containing these varied particle sizes into granules for tableting, the first peak of the power consumption curve declined with decreasing particle size of the physical mixtures and a second peak appeared for physical mixtures with smaller particle sizes. The optimal kneading end point for granules was at the end of the first peak for mixtures with larger particles and at the beginning of the second peak for those with smaller particles.The best granules for tableting prepared from individual physical mixtures at different end points had maximum pore volume and consisted of a mixture of similar size of porous loose agglomerates and bulk powder as reported previously. This inner structure of granules is assumed to induce plastic deformation and particle movement upon compression and to result in high mechanical tablet strength.