Application of external lubrication during the roller compaction of adhesive pharmaceutical formulations

A novel use of external lubrication has been investigated in which magnesium stearate was applied directly to the roll surface during roller compaction. A scalable parameter; travelling roll distance per shot (D(pS)), has been defined which ensures that an equal amount of magnesium stearate is applied to the roll surface per rotation at any roll speed. It was found that a formulation containing 20% w/w of either the API Pravastatin or Ibipinabant required a smaller D(pS) than a placebo formulation in order to prevent roll adherence. The inherent adhesiveness, and hence the required amount of external magnesium stearate to prevent roll adhesion, will depend on the material properties of the formulation. The amount of magnesium stearate transferred from the roll surface to the ribbon was measured using inductively coupled plasma optical emission spectroscopy and was found to be less than 0.01% w/w. This is a significant reduction in magnesium stearate compared to the normal manufacturing procedure of blending 0.25-2.0% w/w within the formulation.The advantage of external lubrication during roller compaction is the significant reduction in magnesium stearate from the formulation which could lead to the production of tablets with superior mechanical properties and faster dissolution times.