Effects of Granulated Lactose Characteristics and Lubricant Blending Conditions on Tablet Physical Properties in Direct Powder Compression

Lactose is an excipient used extensively for bulking, diluting, and molding active pharmaceutical ingredients in tablet manufacturing. Particularly, granulated lactose (GL) intended for direct powder compression has distinct properties due to differences in manufacturing methods. It contributes to handling blended powders for tableting and tablet quality. In this study, we aimed to compare the functions of different forms of GL added as excipients during direct powder compression on the tablet properties and the effect of magnesium stearate (Mg-S) used as a lubricant on each type of GL. Different GL types obtained using different manufacturing methods (agitated granulation, GL-AG; spray-dried granulation, GL-SD; fluidized bed granulation, GL-FB) were blended with maize starch, low-substituted hydroxypropyl cellulose, and paracetamol in a V-type blender for 10 min. Mg-S was added at varying amounts (0.1, 1.0, and 2.0%) and blending times (5, 10, and 30 min) for the nine types of blended powders for tableting formulation. The powders were tableted, and the tablets were evaluated for weight and drug loading variations, tensile strength, friability, and disintegration time. When tablets with the same blending conditions were compared, the tensile strength and disintegration time were in the order of GL-FB > GL-SD > GL-AG. For each GL, we analyzed the effects of changes in the added amount of Mg-S and blending time using contour plots, evaluated the effects of blending conditions on tablet properties, and determined the target tablet properties. We investigated the optimization of the lubricant blending conditions to obtain suitable tablets.