Roller compaction as a method for effervescent tablet preparation

This study was designed to assess the effectiveness of roller compaction as a means of reducing the degradation of aspirin in effervescent tablets, and the subsequent effect that this may have on processing. In addition to the evaluation of roller compaction, the influence of tableting force and dwell time on the interaction of aspirin and sodium bicarbonate was also studied. A factorial statistical design was selected for the evaluation of tableting force and dwell time on the degradation of aspirin when combined with sodium bicarbonate. Samples were exposed to two tableting forces and two dwell times. Half of these samples were stored for six months at two different temperatures, 20 and 40°C. These studies indicated that both force and dwell time are significant factors contributing to aspirin degradation when tableted in combination with sodium bicarbonate. Storage temperature was also found to be significant. The influence of force and dwell time is consistent with current powder consolidation hypotheses such as cold welding, and fusion bonding. In order to thoroughly evaluate roller compaction of an effervescent formulation, a statistical design was selected containing all possible combinations of formulation ingredients. These combinations represented complete effervescent formulations composed of powders, granules or a combination of both powders and granules. Each combination was assessed for chemical stability, processing characteristics, and product quality. These studies have shown that the separation of reactive materials, by means of roller compaction and subsequent granulation, is a viable method to improve product stability while still maintaining good product quality and processing characteristics. While this study has focused on effervescent formulations, this same principle is quite applicable to any tableted system where a physical or chemical incompatibility must be overcome