Epitochem

Sodium Stearyl Fumarate

Sodium Stearyl Fumarate

Sodium stearyl fumarate is a fine, white powder composed of agglomerates of flat, circular-shaped particles. It is practically insoluble in most organic solvents and water at room temperature, though solubility increases with temperature. It has a melting point of 224–245 °C (with decomposition), and a slightly alkaline pH of 8.3 in a 5% w/v aqueous solution at 90 °C. The bulk and tapped densities range from 0.2–0.5 g/cm³.

Chemical Name and CAS Registry Number :-2-Butenedioic acid, monooctadecyl ester, sodium salt [4070-80-8]
Functional Category :-Tablet and capsule lubricant.

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Pharmacopeial Specifications

Test PhEur USPNF
Identification ✔ ✔
Water ≤5.0% ≤5.0%
Assay (anhydrous basis) 99.0–101.5% 99.0–101.5%
Lead — ≤0.001%
Heavy metals — ≤0.002%
Sodium stearyl maleate — ≤0.25%
Stearyl alcohol — ≤0.5%
Saponification value — 142.2–146.0
Related substances ✔ —
Organic volatile impurities — ✔

Applications in Pharmaceutical Formulation or Technology

Used primarily as a lubricant in tablet and capsule formulations, typically at concentrations of 0.5–2.0% w/w. It is especially suitable in formulations where traditional stearate lubricants (like magnesium stearate) may interfere with drug dissolution or compatibility. Sodium stearyl fumarate has a lower hydrophobicity than magnesium stearate, minimizing its impact on dissolution profiles.

Comment

Sodium stearyl fumarate is a preferred alternative to magnesium stearate when issues like delayed dissolution or incompatibility arise. Its lower hydrophobic nature contributes to better dissolution performance in some formulations. It is chemically pure and well-suited for sensitive drug products. A monograph is included in the Food Chemicals Codex (FCC). The excipient is GRAS-listed and permitted in pharmaceuticals and some food applications.

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