Internal lubrication can be associated with reduced tabletability. Deformation mechanism, lubricant type, lubricant blending time and paddle speed (PS) of the forced feeder are known to be influenceable factors. This study investigated the effect of lubricant blending time and PS of forced feeders on the tensile strength of lubricated microcrystalline cellulose (MCC) and lactose tablets. Magnesium stearate (MgSt), sodium stearyl fumarate (SSF) and stearic acid (SA) were used as lubricants. Tablets were produced on a compaction simulator and a rotary tablet press to investigate lubricant sensitivity during upscaling. Lubricant sensitivity was found higher for MCC compared to lactose which was attributed to the higher plasticity of MCC. The reduction in tensile strength upon lubricant addition followed the order: MgSt > SSF > SA; which could be linked to particle size, specific surface area and particle shape of the lubricants. Although differences in tensile strength were observed between the lubricant types, comparable ejection forces were obtained. The impact of PS on tensile strength was higher compared to lubricant blending time for both tableting machines. A good correlation of tensile strength and lubricant sensitivity between the compaction simulator and rotary tablet press was observed based on the calculation of paddle passes (NPP).
Keywords: Compaction simulator; Direct compression; Internal lubrication; Lubricant sensitivity; Powder compaction; Upscaling.
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