EFFECT OF COMMERCIAL AND HIGH-PURITY MAGNESIUM STEARATES ON INVITRO DISSOLUTION OF PARACETAMOL DC TABLETS

The effects of several commercial grades and a high-purity magnesium stearate on in vitro dissolution of paracetamol DC tablets have been studied. In each case, 0.5% w/w concentration of the lubricant was added to the paracetamol DC granules and mixed for a pre-determined time interval. Tablets of equivalent weight and dimensions were prepared from paracetamol DC and the lubricated mixtures for direct comparison of in vitro dissolution. Whilst the commercial magnesium stearates show marked differences in dissolution between the various grades, all retarded dissolution to a greater extent than the high-purity sample. The in vitro dissolution of unlubricated and lubricated paracetamol DC tablets has been compared. The role of hydrophobic lubricant films has been discussed in terms of magnesium stearate influence on in vitro dissolution. The superior dissolution data for tablets lubricated with high-purity magnesium stearate confirmed the hypothesis that the hydrophobic film formation propensity of commercial and high-purity magnesium stearate is different.