Sodium Stearyl Fumarate Excipient | Uses, Suppliers, and Specifications
Sodium Stearyl Fumarate is 2-Butenedioic acid (E)-, monoactadecyl ester, sodium salt, a synthetic organic salt corresponding to the chemical formula C22H29NaO4 and a pharmaceutical excipient. It may thus be described as a long-chain fatty acid with weak basic properties. Sodium stearyl fumarate is supplied as a fine white powder, which may agglomerate or form clumps. Under light magnification, it appears in the form of circular-shaped particles.
Pharmacopoeial Compliance: USP-NF; Ph.Eur; B.P; J.P; I.P
Synonyms and Trade Names: Sodium Stearyl Fumarate; Fumaric Acid, Actadecyl Ester, Sodium Salt; Pruv®; ALUBRA®; LUBRIPHARM®; LubriSanaq®
Uses and Applications: Tablet and Capsule Lubricant
Sodium stearyl fumarate is a monoester of fumaric acid used as a water soluble lubricant in the development of various solid dosage forms. it corresponds to Sodium octadecyl fumarate (chemical formula C22H29NaO4), rendering it a fatty acid ester albeit with weak basic properties. It is produced by reacting stearyl alcohol with maleic anhydride. The product of this reaction then undergoes an isomerization step followed by salt formation to produce sodium stearyl fumarate.
In the world of lubricants, Sodium stearyl fumarate is a relatively new material. One of the earliest studies on its functionality was in 1979 by two Swedish researchers Hölzer and Sjögren working at Astra Zeneca, Mölndal, who suggested it as a good substitute for magnesium stearate.
For this reason, Sodium stearyl fumarate is frequently selected when the less pure stearate-type lubricants are unsuitable owing to chemical incompatibility. Since sodium stearyl fumarate is less hydrophobic than magnesium stearate or stearic acid it has minimal effect on tablet dissolution when compared with magnesium stearate.
Sodium stearyl fumarate is supplied as a fine, white powder with agglomerates of flat, circular-shaped particles.
Chemical Structure & Identifiers
|2-Butenedioic acid monooctadecyl ester sodium salt
|CAS Registration Number
|UNII Code (FDA)
Sodium stearyl fumarate is an approved excipient. It is listed in the B.P; I.P, Ch.P, USP-NF and Ph.Eur, is additionally GRAS listed and included in the US FDA Inactive Ingredients Database (covering oral tablets and capsules). It is also permitted by the US FDA for use in food products both for human and animal consumption (up to 0.2 – 1.0% w/w). A specification for Sodium stearyl fumarate is contained in the Food Chemicals Codex (FCC).
|White powder, may agglomerate
|pH = 8.3 for a 5% w/v aqueous solution at 900C
|Log P (ChemAxon)
|224.-2450C (with decomposition)
|Sparingly soluble in water (0.0003 g/l) at 25 oC; Soluble in methanol; insoluble in ethanol
|Specific surface area
|Sodium stearyl fumarate
|Sodium stearyl fumarate
|Sodium stearyl fumarate
|Sodium stearyl maleate
Key: n/a Specification is not listed
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Applications in Pharmaceutical Formulations or Technology
The principal use of Sodium stearyl fumarate is as a tablet and capsule lubricant. The typical concentrations are 0.5 – 2.0% w/w. It is also used in certain food applications and nutraceutical formulations. It is useful in formulations or processes where lubricants are likely to cause problems, such as the potential to slow down dissolution or produce weak tablets, for instance, when magnesium stearate is selected.
Advantages of Sodium stearyl fumarate over Magnesium stearate
- Relatively inert (Magnesium stearate is incompatible with several APIs, including aspirin, iron salts, alkaloid salts, miconazole, triamcinolone, nifedipine, ibuprofen, ramipril, diclofenac, clarithromycin, omeprazole, and azathioprine)
- Is more hydrophilic than magnesium stearate
- Is closest in morphology to Magnesium stearate of all the alternative lubricants
- Does not reduce tablet strength to the same extent as Magnesium stearate
- Is not animal-derived
- Fully compendial
Sodium stearyl fumarate is supplied in a very high state of purity making it highly advantageous when the less pure stearate-type lubricants are unsuitable owing to chemical incompatibility. Furthermore, since it is less hydrophobic than magnesium stearate or stearic acid it has a less retardant effect on tablet dissolution. However, Sodium stearyl fumarate is comparatively more expensive and therefore its selection must be justified by the added cost of the formulation.
Safety and Precautions
Sodium stearyl fumarate is approved for use in oral pharmaceutical formulations and food products. It is generally regarded as a nontoxic and nonirritant material. Several studies in rat and dog models have shown that Sodium stearyl fumarate has a bioavailability of 80%. Following uptake, approximately 35% of the material is hydrolyzed to Stearyl alcohol and Fumaric acid, with the stearyl alcohol further oxidized to stearic acid. Both Stearyl alcohol and stearic acid are naturally occurring constituents and therefore present no serious concerns in terms of their long-term effects on the body.
Stability and Storage Conditions
Sodium stearyl fumarate is a stable excipient (assigned shelf life of 24-36 years) when stored correctly. To ensure long-term stability, the bulk material should be stored in a well-closed container in a cool, dry place away from direct sunlight.
Although the material is not a known irritant, workers should observe established SHEQ protocols appropriate to the circumstances and quantity of material being processed. Aim to work in a well-ventilated place and eye protection and the use of PPE are advised.
Sustainability and Environmental Impact
A sustainability score for Sodium stearyl fumarate has not been provided.
Manufacturers & Suppliers
Additional Resources (Downloads)
References and Literature Used
 G.K. Bolhuis, A.J. Smallenbroek, C.F. Lerk, Interaction of tablet disintegrants and magnesium stearate during mixing I: Effect on tablet disintegration, Journal of Pharmaceutical Sciences, 70 (1981) 1328-1330.
 N.H. Shah, D. Stiel, M. Weiss, M.H. Infeld, A.W. Malick, Evaluation of two new tablet lubricants-sodium stearyl fumarate and glyceryl behenate. Measurement of physical parameters (compaction, ejection and residual forces) in the tableting process and the effect on the dissolution rate, Drug Development and Industrial Pharmacy, 12 (1986) 1329-1346.
 D.S. Desai, B.A. Rubitski, S.A. Varia, A.W. Newman, Physical interactions of magnesium stearate with starch-derived disintegrants and their effects on capsule and tablet dissolution, International Journal of Pharmaceutics, 91 (1993) 217-226.
 G.M. Mahrous, M.A. Ibrahim, H.F. Mostafa, E.M. Elzayat, Application of a quality-by-design approach for utilizing sodium stearyl fumarate as a taste-masking agent in dextromethorphan hydrobromide orally disintegrating tablets, Pharmaceutical Development and Technology, 24 (2019) 711-719.
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