Polyoxyethylene alkyl ethers

• BPMacrogol Cetostearyl Ether
• BPMacrogol Lauryl Ether
• BPMacrogol Oleyl Ether
• JPLauromacrogol
• Ph. Eur.Macrogol Cetostearyl Ether
• Ph. Eur.Macrogol Lauryl Ether
• Ph. Eur.Macrogol Oleyl Ether
• Ph. Eur.Macrogol Stearyl Ether
• USP–NFPolyoxyl 10 Oleyl Ether
• USP–NFPolyoxyl 20 Cetostearyl Ether

Brij; cetomacrogol 1000; ceteareth; Cremophor A; Eumulgin; laureth; lauromacrogol; macrogol ethers; oleth; polidocanol; polyoxyl ethers; steareth; Volpo

Polyoxyethylene glycol ethers of fatty alcohols (for example lauryl, cetyl, stearyl, cetostearyl and oleyl alcohols) · [—]

CH3(CH2)x(OCH2CH2)yOH (x typically 11–17; y typically 2–100)

Surfactant, emulsifier

Typical concentrations: — · Dosage forms: Semi-solid

Nonionic surfactants used as emulsifying agents in oil-in-water and water-in-oil creams and lotions, as solubilisers for essential oils, perfumes and poorly soluble drugs, and as wetting agents; cetomacrogol 1000 is the emulsifier in cetomacrogol emulsifying wax and the corresponding creams. Typical levels: emulsifying agent about 0.5–15%, solubilising agent about 1–10%, wetting agent about 0.1–3%. Polidocanol (lauromacrogol 400) is also used in its own right as a sclerosant and topical antipruritic.

A series of nonionic surfactants made by attaching polyoxyethylene chains of varying length to fatty alcohols. They are named from the alcohol and the average number of ethylene oxide units (for example polyoxyl 20 cetostearyl ether or ceteareth-20). They range from colourless or pale yellow liquids to white or cream-coloured waxy solids with a faint characteristic odour.

Physical form

liquids, pastes or waxy solids, depending on the alkyl chain length and number of ethylene oxide units

HLB

wide range, from about 5 (short polyoxyethylene chains) to about 17 (long chains); e.g. cetomacrogol 1000 ≈ 15.7, polyoxyl 23 lauryl ether ≈ 16.9

Solubility

types with few ethylene oxide units are oil-soluble and water-dispersible; types with many units are soluble in water and ethanol

Cloud point

varies with structure; aqueous solutions of the hydrophilic types become turbid on heating

Being ethers, they are chemically stable in strongly acidic and alkaline conditions. The polyoxyethylene chain can undergo autoxidation on storage, forming peroxides, so they should be stored in airtight containers, protected from light, in a cool, dry place.

Discoloration or precipitation can occur with iodides, mercury salts, phenolic substances, salicylates, sulfonamides and tannins. They can reduce the antimicrobial activity of preservatives, notably parabens and phenols, by micellar binding, and peroxide impurities may oxidise sensitive drugs.

Prepared by reacting fatty alcohols with ethylene oxide under alkaline catalysis; the amount of ethylene oxide determines the average polyoxyethylene chain length.

Widely used in topical products and generally regarded as non-toxic and non-irritant at the levels used, although skin and eye irritation can occur with some types and at high concentrations. Polidocanol is administered by intravenous injection as a sclerosant.

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

Included in the FDA Inactive Ingredient Database (topical and other non-parenteral preparations) and in non-parenteral medicines licensed in Europe.

Cetomacrogol emulsifying wax; poloxamer; polyoxyethylene castor oil derivatives; polyoxyethylene stearates; polysorbates.

Combining a low-HLB and a high-HLB member of the series is a common way of making stable emulsions with the required HLB. Because the ether link is not hydrolysed, these surfactants are preferred over ester-type surfactants such as polysorbates in formulations at extreme pH.