Sorbitan monostearate (Span 60)

• BPSorbitan Stearate
• Ph. Eur.Sorbitan Stearate
• USP–NFSorbitan Monostearate

Sorbitan stearate; sorbitani stearas; Span 60; Arlacel 60; Crill 3; E491

Sorbitan mono-octadecanoate (partial esters of sorbitol and its mono- and dianhydrides with stearic acid) · [1338-41-6]

UNII NVZ4I0H58X · PubChem CID 16218600

C24H46O6 · 430.6

Surfactant, emulsifier

Typical concentrations: — · Dosage forms: Semi-solid

A lipophilic nonionic surfactant used as an emulsifier and stabiliser in water-in-oil creams and ointments, as a co-emulsifier with polysorbates (for example polysorbate 60) in oil-in-water creams, and as a consistency-improving agent. It is also used in foods, for example in yeast, cake mixes and confectionery coatings, and in the preparation of niosomes and organogels. Typical concentrations: emulsifier used alone in water-in-oil emulsions 1–15%; in combination with hydrophilic emulsifiers in oil-in-water emulsions 1–10%; to increase the water-holding capacity of ointments 1–10%; solubiliser for poorly soluble actives in lipophilic bases 1–10%; wetting agent for insoluble actives in lipophilic bases 0.1–3%.

A cream to light tan, waxy solid supplied as beads, flakes or powder, with a faint characteristic odour and a bland taste. It is a mixture of esters of stearic and palmitic acids with sorbitol anhydrides.

HLB

4.7

Physical form

waxy solid at room temperature; melts at roughly 50–60 °C

Solubility

insoluble but dispersible in warm water; soluble in warm mineral and vegetable oils at higher temperatures; slightly soluble in ether

Gradual soap formation occurs with strong acids or bases; the esters are stable in weak acids and bases. Store in a well-closed container in a cool, dry place.

Incompatible with strong oxidising agents. Like other nonionic surfactants, it may reduce the activity of some preservatives such as parabens.

Prepared by dehydration of sorbitol to sorbitan followed by esterification with commercial stearic acid (a mixture of stearic and palmitic acids), or by direct reaction of sorbitol with the fatty acid at high temperature with a catalyst.

Sorbitan esters are widely used in cosmetics, foods and oral and topical pharmaceuticals and are generally regarded as non-toxic and non-irritant, although hypersensitivity skin reactions have occasionally been reported after topical use.

Observe normal precautions for the quantity handled. Eye protection and gloves are recommended.

Accepted as a food additive in Europe (E491) and permitted as a direct food additive in the USA. Included in the FDA Inactive Ingredient Database (oral, topical and vaginal preparations, among others) and in non-parenteral medicines licensed in Europe.

Polysorbate 60; sorbitan monolaurate (Span 20); sorbitan monooleate (Span 80); sorbitan tristearate; glyceryl monostearate.

Because it is solid at room temperature, it is melted with the oil phase during emulsion preparation. Its saturated fatty-acid chains make it more resistant to oxidation than sorbitan monooleate and give firmer creams.