E572 (Magnesium Stearate)  is a chemical compound, magnesium salt of stearic acid (octadecanoic acid). It occurs as a light, white, fine powder, insoluble in water, ethoxyethane, ethanol, ether. Soluble in hot water, hot ethanol. On contact with acids it decomposes into stearic acid and magnesium sal's salts.  Commercially it is not pure, but it is a mixture of Magnesium Stearate and Magnesium Palmitate (C₃₂H₆₂MgO₄) extracted from palm oil.

Magnesium stearate has four types of pseudopolymers: monohydrate, dihydrate, trihydrate, anhydrate.

What it is used for and where it is used

Medical

In the pharmaceutical industry, it is an excipient for solid oral dosage forms. It is used as an essential lubricant in production for tablet dissolution, disintegration and hardness.

Hydroxypropyl methyl cellulose can prevent drug precipitation caused by magnesium stearate (1). It is used as a lubricant in the nanoprecipitation/ion exchange method (2). This study investigates magnesium stearate used as an essential lubricant in tablet production and its effect on tablet dissolution, disintegration and hardness (3).

Food. 

Labelled as an anti-caking agent with the number E572 in the list of European food additives for chocolate and chocolate derivatives, cocoa, candied fruit etc. where it has an anti-caking function. 

Other uses

In the plastics industry it is used as a lubricant and stabiliser for cellulose acetate, polyvinyl chloride, ABS, resins etc.

Cosmetics 

Anticaking agent. This compound facilitates free flow and prevents aggregation or clumping of substances in a formulation by reducing the tendency of certain particles to stick together

Bulking agent. It regulates the water content, dilutes other solids, can increase the volume of a product for better flow, acts as a buffer against organic acids, helps to keep the pH of the mixture within a certain level.

Colorant. This ingredient has the function of colouring the solution in which it is inserted in a temporary, semi-permanent or permanent manner, either alone or in the presence of the complementary components added for colouring.

Moisturizing. This ingredient is responsible for preventing the evaporation of moisture from the skin and improving cellular activity. When exposed to cold or hot air currents, the skin absorbs water from its inner layer to compensate for the evaporated water. If the draught phenomenon persists, the stratum corneum is dry and, if at all, damaged.

The most relevant studies on this chemical compound have been selected with a summary of their contents:

Magnesium Stearate studies

Optimal typical characteristics of Magnesium Stearate as a commercial cosmetic product 

• Molecular Formula   C₃₆H₇₀MgO₄    Mg(C₁₈H₃₅O₂)₂
• Linear Formula   [CH₃(CH₂)₁₆CO₂]₂Mg
• Molecular Weight  591.257 g/mol
• Exact Mass    590.512451
• CAS  557-04-0
• EINECS 209-150-3
• UNII 70097M6I30
• DSSTox Substance ID: DTXSID2027208
• MDL number  MFCD00036391
• PubChem Substance ID 24865972
•  InChI Key    HQKMJHAJHXVSDF-UHFFFAOYSA-L
• SMILES    CCCCCCCCCCCCCCCCCC(=O)[O-].CCCCCCCCCCCCCCCCCC(=O)[O-].[Mg+2]
• IUPAC Name    magnesium;octadecanoate
• ChEBI    CHEBI:9254
• Beilstein  3919702
• NACRES  NA.22

Synonyms:

• Stearic acid magnesium salt
  
• Magnesium octadecanoate
• Magnesium distearate
• magnesium dioctadecanoate
• Octadecanoic acid, magnesium salt
• Dibasic magnesium stearate
• octadecanoic acid magnesium salt

References_________________________________________________________________________

(1) Démuth B, Galata DL, Balogh A, Szabó E, Nagy B, Farkas A, Hirsch E, Pataki H, Vigh T, Mensch J, Verreck G, Nagy ZK, Marosi G. Application of hydroxypropyl methylcellulose as a protective agent against magnesium stearate induced crystallization of amorphous itraconazole. Eur J Pharm Sci. 2018 Aug 30;121:301-308. doi: 10.1016/j.ejps.2018.06.008.

(2) Martínez-Acevedo L, Zambrano-Zaragoza ML, Vidal-Romero G, Mendoza-Elvira S, Quintanar-Guerrero D. Evaluation of the lubricating effect of magnesium stearate and glyceryl behenate solid lipid nanoparticles in a direct compression process. Int J Pharm. 2018 Jul 10;545(1-2):170-175. doi: 10.1016/j.ijpharm.2018.05.002. 

(3) Yamamoto K, Tamura T, Yoshihashi Y, Terada K, Yonemochi E. Effect of Magnesium Stearate Mono- and Dihydrate Dispersibilities on Physical Properties of Tablets. Chem Pharm Bull (Tokyo). 2017;65(11):1028-1034. doi: 10.1248/cpb.c17-00429.