Some effects of humidity and heat on the tableting properties of microcrystalline cellulose formulations



Journal Title

Journal ISSN

Volume Title



Microcrystalline cellulose has gained recognition as an outstanding tableting agent for use in the direct compression of pharmaceutical tablets. During preliminary work at the University of Houston it was observed that microcrystalline cellulose which had been exposed to the normal atmospheric conditions of the tableting room did not perform as well as did material drawn from the original, closed container of the same batch of the material. No mention of this was found in the literature. Several procedures were suggested as possible ways to improve the tableting properties of the exposed microcrystalline cellulose. From among them, the following three were selected for experimental work: 1. To heat the exposed material and to feed it to the tableting press without allowing it to cool. If adsorbed moisture was responsible for the change in the tableting properties, the exposure to heat should drive off the moisture. 2. To lubricate the exposed material with magnesium stearate. This would tend to improve its flow properties since magnesium stearate is an efficient glidant type of lubricant. 3. To combine the effects of heat and lubrication. It was thought that the combination of the two procedures might result in a synergistic improvement in the flow and tableting properties of the material. It was found that microcrystalline cellulose which was heated after being exposed to atmospheric conditions for a three week period, demonstrated a statistically significant improvement in its tableting characteristics. Under comparable press conditions, material which had been exposed, heated and tableted gave heavier, harder tablets than did the same material which was simply exposed and then tableted. The heating step was carried out at temperatures of 37 and 57 degrees C., in separate experiments. In both cases, the use of heat improved the properties of the tablets over those produced from the exposed, unheated material. The use of magnesium stearate as a lubricant served to improve the flow properties of both the heated and unheated microcrystalline cellulose. In both cases, however, the final tablets were lacking in hardness, and were therefore not entirely satisfactory for pharmaceutical end uses.