Magnesium stearate

Magnesium stearate (CAS 557-04-0) is a magnesium salt of stearic acid, commercially known under names including Dolomol and magnesium distearate. It carries no E-code designation and is classified under HS code 29157030. The molecular formula is C18H36O2.1/2Mg.

In pharmaceutical tablet manufacturing, magnesium stearate functions as a die lubricant, reducing friction between the tablet mass and tooling surfaces to prevent sticking and ensure consistent ejection forces. In plastics processing, it acts as a heat stabilizer and internal lubricant, reducing polymer degradation during high-temperature extrusion. Cosmetic formulators use it as an emulsion stabilizer and slip agent in pressed powders.

Magnesium stearate is available in pharmaceutical-grade (Ph.Eur., USP/NF), food-grade (FCC), and technical-grade forms. It is subject to REACH registration requirements within the EU. Typical packaging includes 25 kg bags, with bulk options available depending on grade and supplier specifications.