Polyethylene oxide

• USP–NFPolyethylene Oxide

Polyox WSR; Polyox WSR 301; Polyox WSR 303; Polyox WSR Coagulant; Polyox WSR N-10; Polyox WSR N-80; Sentry Polyox; polyoxirane; PEO

Poly(oxy-1,2-ethanediyl), α-hydro-ω-hydroxy- · [25322-68-3]

(CH2CH2O)n, n ≈ 2 000–200 000 · ≈ 100 000–7 000 000 (approximate average, depending on grade)

Release-modifying polymer, Binder

Typical concentrations: — · Dosage forms: Solid

Used as a hydrophilic matrix former in extended-release tablets, as the swelling 'push' layer in osmotic pump tablets, as a tablet binder, mucoadhesive and thickening agent, and in hot-melt extrusion. High-molecular-weight grades are used in abuse-deterrent tablets because they make the tablet hard to crush and form viscous gels that hinder extraction and injection. Concentrations range from about 5% as a binder to well over 50% in extended-release matrices.

A non-ionic homopolymer of ethylene oxide of high molecular weight. It is chemically similar to polyethylene glycol but of much higher chain length, and is supplied as a white to off-white, free-flowing powder; commercial grades usually contain a small amount of antioxidant (BHT) and may contain fumed silica as a flow aid.

Physical form

white to off-white, free-flowing powder with a slight ammoniacal odour

Melting point

about 65–70 °C (crystalline polymer)

Solubility

soluble in water, forming viscous solutions; soluble in some organic solvents such as acetonitrile and chloroform; insoluble in aliphatic hydrocarbons

Viscosity

strongly grade dependent; solution viscosity rises steeply with molecular weight

The powder is stable when stored in a cool, dry place in a tightly closed container. The polymer is susceptible to oxidative chain scission, which lowers viscosity; this is accelerated by heat, UV light, transition-metal ions and peroxides, and solutions also lose viscosity under high shear.

Incompatible with strong oxidising agents. Residual peroxides and oxidative degradation products may affect oxidation-sensitive drugs.

Produced by catalytic (heterogeneous) polymerisation of ethylene oxide to give very long polyether chains.

Regarded as non-toxic and non-irritant at the levels used in oral products; because of its high molecular weight it is very poorly absorbed from the gastrointestinal tract.

Observe normal precautions for the quantity handled. Avoid dust generation and inhalation; eye protection, gloves and a dust mask are recommended. Spilled powder becomes very slippery when wet.

Included in the FDA Inactive Ingredient Database (oral tablets, including extended-release tablets, and other non-parenteral preparations) and in non-parenteral medicines licensed in Europe.

Polyethylene glycol; poloxamer.

In matrix tablets the rate of drug release is controlled mainly by the molecular weight and level of the polymer. To prepare solutions, disperse the powder in water with vigorous stirring (or pre-wet it with a non-solvent such as ethanol) to avoid lumps, then stir slowly to avoid shear degradation.