MgSt is a mixture of stearate and palmitate [4]. Several different hydrates and corresponding solid-state forms of MgSt have been identified: anhydrous, monohydrate (acicular or disordered), dihydrate (plate), trihydrate (acicular) [14, 15 ]. MgSt samples may contain crystalline (single or a combination of two or more forms) or disordered forms [15]. Molecular, structural, particle properties, and excipient levels have been identified as potential key material properties of MgSt [4]. The purity of MgSt (ratio of stearic acid to palmitic acid) may affect its lubricating efficiency. The dissolution delay of a highly soluble drug (paracetamol, United States Pharmacopeia (USP) 2 apparatus, 0.1 N HCl pH 1, 25 rpm, 37°C) was more pronounced in the presence of commercial MgSt (a mixture of pharmaceutical grade stearic acid) and stearin palmitate with not less than 40% acid content) compared with high-purity MgSt (90% stearic acid) [9]. The slower drug dissolution stearate was attributed to the formation of an extensive hydrophobic layer around the particles in the commercial product compared to high-purity MgSt. MgSt forms a hydrophobic layer around the particles depending on the solid state form of the excipient. Due to its irregular shape, the disordered MgSt hinders the formation of a smooth film around the particles [16]. Grinding crystalline MgSt destroys its crystal structure, resulting in less crystalline material, which exhibits poor lubrication efficiency [17]. The importance of the degree of crystallinity (CRS) is emphasized because the negative effect of disordered MgSt on lubrication can dominate the lubrication efficiency of the crystalline fraction [18]. Coating strength and uniformity depend on the particle size distribution (PSD) of the lubricant. Due to their higher adhesion on the surface, smaller particles form a thin, uniform layer, while larger particles have relatively less tendency to stick to the surface, resulting in a less uniform coating[ 4]. A statistical evaluation of the factors affecting the lubrication efficiency of MgSt revealed that, for crystalline MgSt, moisture content, Hausner ratio, PSD (d50) and specific surface area (SSA) are key material properties [18]. Finally, the level of excipients in solid dosage forms may affect the coating efficiency of MgSt and its effect on product performance. Tablet disintegration and drug dissolution have been reported to be significantly delayed when increasing the amount of MgSt in the formulation, which is a consequence of reduced tablet wettability