Sodium stearyl fumarate

• BPSodium Stearyl Fumarate
• Ph. Eur.Sodium Stearyl Fumarate
• USP–NFSodium Stearyl Fumarate

Fumaric acid octadecyl ester sodium salt; natrii stearylis fumaras; sodium monostearyl fumarate; Lubripharm; Pruv

Sodium (E)-4-octadecoxy-4-oxobut-2-enoate (monosodium octadecyl fumarate) · [4070-80-8]

UNII 7CV7WJK4UI · PubChem CID 23665634

C22H39NaO4 · 390.5

Lubricant

Typical concentrations: 0.5–2% · Dosage forms: Solid

Used as a tablet and capsule lubricant at about 0.5–2.0% w/w. It is chosen in place of magnesium stearate when that lubricant is incompatible with the drug, slows dissolution or gives soft tablets, as it is less hydrophobic and less sensitive to over-blending. It is also used in effervescent and orally disintegrating tablets, and in some food applications.

A fine, white powder with agglomerates of flat, circular particles. Pharmacopoeial material limits the related impurities sodium stearyl maleate and stearyl alcohol.

Melting point

about 224–245 °C, with decomposition

Solubility

practically insoluble in water, acetone and ethanol; slightly soluble in methanol

Sodium stearyl maleate

not more than 0.25% (Ph. Eur.)

Stearyl alcohol

not more than 0.5% (Ph. Eur.)

Stable when stored in a well-closed container in a cool, dry place.

It has been reported to be incompatible with chlorhexidine acetate. As an ester, it may react with strongly basic or nucleophilic drugs under adverse conditions.

Prepared by reacting stearyl alcohol with maleic anhydride to give the monoester, which is isomerised to the fumarate and then converted to the sodium salt.

Partly absorbed and hydrolysed to stearyl alcohol and fumaric acid, which are metabolised; the unabsorbed portion is excreted in the faeces. It is regarded as non-toxic at the levels used.

Observe normal precautions for the quantity handled. Avoid inhaling the dust; eye protection, gloves and a dust mask are recommended.

Permitted as a direct food additive in the USA for specified uses. Included in the FDA Inactive Ingredient Database (oral capsules and tablets) and in non-parenteral medicines licensed in Europe.

Magnesium stearate; glyceryl behenate; stearic acid; sodium lauryl sulfate.

Compared with magnesium stearate it usually gives harder tablets, faster dissolution and less dependence on blending time, though a slightly higher concentration may be needed for equivalent lubrication. It is a useful option for drugs that interact with stearate salts.