Application of multivariate methods to evaluate the functionality of bovine- and vegetable-derived magnesium stearate

This work distinguishes and quantifies the effects of bovine- and vegetable-derived magnesium stearate (MgSt) molecular and macroscopic properties on lubrication efficiency using multivariate analysis. Principal component analysis (PCA) and partial least-square regression (PLS) were used to evaluate and quantify the lubricant effectiveness on a model tablet formulation. PCA score and loading plots showed a separation of model formulations based on the MgSt sources, which indicated different bovine- and vegetable-derived MgSt lubrication potential. PLS quantified the MgSt molecular [enthalpy of dehydration (ΔHd), enthalpy of melting (ΔHm), percent crystallinity, and moisture content] and macroscopic [particle size (d50 ), specific surface area (SSA-MgSt), and MgSt Hausner ratio (HF-MgSt)] properties, their interactions, and square effects on formulation powder flow and tableting properties relating to MgSt's lubrication effectiveness. For crystalline MgSt, moisture content, HF-MgSt, d50 , and SSA-MgSt showed a major influence on the lubrication efficiency compared with the other MgSt molecular properties (percent crystallinity, ΔHm, and ΔHd). Amorphous MgSt showed poor lubrication, and none of its molecular or macroscopic properties showed significant effects on lubrication efficiency.