EFFECT OF MIXING TIME ON THE LUBRICATING PROPERTIES OF MAGNESIUM STEARATE AND THE FINAL CHARACTERISTICS OF THE COMPRESSED TABLETS

The effect of mixing time on hardness, disintegration time and ejectio n force in tabletting of magnesium stearate and lactose granules was s tudied. The hardness of the tablets decreased with an increase in mixi ng time of the blends, as previously reported. A semilogarithmic plot of the hardness versus mixing time gave a straight line having a turni ng point. At the early phase of mixing the hardness was decreasing wit h a large first-order rate and then continued to decrease with another small first-order rate. The change in disintegration time or ejection force versus mixing time was basically the same as that in the hardne ss. This type of plot was applicable to the mixing magnesium stearate with not only granular but also powdered materials.