The internal blending of magnesium stearate is often associated with decreasing tensile strengths and longer disintegration and dissolution times. Therefore, external lubrication has gained interest in the pharmaceutical industry as these negative effects could be minimized using this method. In this study, an external lubrication system implemented in a compaction simulator was investigated. The influence of 2 process parameters related to the external lubrication system, spraying time and atomizing pressure, on the responses was studied using 4 common fillers and 2 model drugs. While the parameters of the external lubrication system had a significant impact on the ejection forces, no negative effect was observed on the tensile strength and disintegration time as similar values were obtained compared to non-lubricated experiments. Moreover, equal or lower ejection forces were obtained for external lubrication using a lower concentration of magnesium stearate compared to internal lubrication, where a decrease in tensile strength and prolonged disintegration was noticed for most formulations. The observed results could be correlated to the wall friction angle, compaction properties and tablet brittleness index of the raw materials and blends. This study showed the potential of external lubrication as an alternative lubrication method for lubricant-sensitive formulations.
Keywords: Compaction simulator; External lubrication; Lubrication; Magnesium stearate; Powder compaction; Tablet properties.
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