INFLUENCE OF COMMERCIAL AND HIGH-PURITY MAGNESIUM STEARATES ON SODIUM-CHLORIDE AND PARACETAMOL DC GRANULES DURING TABLETTING

Tablets of standardised weight and dimension were prepared on an instrumented single-punch tablet machine, either from unlubricated samples or lubricated binary mixtures containing 0.5% w/w magnesium stearate of commercial or high purity grade. From dynamic compaction data. Heckel plots were constructed and critical parameters measured for comparison. The results indicated that sodium chloride consolidated primarily by plastic deformation and paracetamol DC by fragmentation and plastic deformation. The presence of magnesium stearate did not appear to alter deformation mechanisms, but, as expected, increased compression force transmission ratio, R, and reduced ejection force, EJF. Lubricant effects on yield pressure, P(y), and densification due to particle slippage, D(B), revealed differences between sodium chloride and paracetamol DC and results have been discussed in terms of inter-particulate rearrangement and crystalline slip-plane compaction. The crushing strength, CS, for tablets prepared from lubricated sodium chloride and paracetamol DC was reduced compared with unlubricated systems with a greater change for sodium chloride systems. Overall the high purity magnesium stearate was found to be as effective a powder lubricant as the commercial samples tested.