The effect of magnesium stearate and sodium starch glycolate on powder flowability

Abstract

The powder flow plays an important role in the manufacture of dosage form such as direct compression tablets. The objective of this research was to investigate the individual and interaction effects of magnesium stearate (MgSt) (Merck Ltd., Germany) as lubricant and sodium starch glycolate (SSG) (Primojel?) as superdesintegrator on powder flowability. Powder formulations were prepared by mixing different concentration of MgSt (0.25% and 5%) and SSG (0.5% and 4%) with microcrystalline cellulose (MCC) (Vivapur?101) or spray-dried lactose (LAC) (Super Tab 21AN) as diluents. Eight powder formulations were prepared using as filler LAC and MCC, as superdesintegrator SSG and as lubricant MgSt in ratios as follows: P1 (LAC : 0.5% SSG : 0.25% MgSt); P2 (LAC : 4% SSG : 5% MgSt); P3 (LAC : 0.5% SSG : 5% MgSt); P4 (LAC : 4% SSG : 5% MgSt); P5 (MCC : 0.5% SSG : 0.25% MgSt); P6 (MCC : 4% SSG : 5% MgSt); P7 (MCC : 0.5% SSG : 5% MgSt); P8 (MCC : 4% SSG : 0.25% MgSt). The powder formulations were evaluated using indirect methods of flowability evaluation according to 9th European Pharmacopoeia: measurement of tapped and bulk density (Ph.Eur.9, 2.9.34) and angle of repose (Ph.Eur. 2.9.36). Also, compressibility index, Hausner?s ratio were calculated. A full factorial design with three factors at two levels and response surface methodology were applied to evaluate the influence of various concentrations of MgSt and SSG on powder flowability. The results indicate that flow properties improved with decrease of SSG content and with increase of MgSt content. Magnesium stearate in powder formulations with microcrystalline cellulose has a greater influence on the improvement of the flow properties than powder formulations with spray-dried lactose.