Polyvinyl alcohol

• BPPoly(vinyl Alcohol)
• Ph. Eur.Poly(vinyl Alcohol)
• USP–NFPolyvinyl Alcohol

Elvanol; Gohsenol; Mowiol; Poly(vinyl alcohol); Polyviol; PVA; vinyl alcohol polymer; E1203

Ethenol, homopolymer (partially or fully hydrolysed poly(vinyl acetate)) · [9002-89-5]

(C2H4O)n · ≈ 20 000–200 000

Coating agent, film former, Gelling agent, viscosity modifier

Typical concentrations: — · Dosage forms: Solid, Sterile (parenteral/ophthalmic)

Used mainly in topical and ophthalmic preparations as a viscosity-increasing agent and lubricant, for example in artificial tears and contact lens solutions, and as a stabiliser of emulsions. It is the film-forming polymer of several immediate-release film-coating systems, is used in transdermal and film dosage forms and peel-off gels, and is widely used as the stabiliser of the external aqueous phase in preparing polymeric microspheres. Typical concentrations: emulsions about 0.5%; ophthalmic preparations 0.25–3.0%; topical lotions about 2.5%.

A water-soluble synthetic polymer supplied as an odourless, white to cream-coloured granular powder. Grades are classified by degree of hydrolysis (partially hydrolysed, about 87–89%, or fully hydrolysed, about 98–99%) and by the viscosity of a 4% w/v aqueous solution.

Degree of hydrolysis

partially hydrolysed about 87–89%; fully hydrolysed about 98–99%

Viscosity

from a few mPa s to about 65 mPa s (4% w/v aqueous solution at 20 °C), depending on grade

pH

5.0–8.0 (4% w/v aqueous solution)

Solubility

soluble in water, more readily on heating (partially hydrolysed grades dissolve more easily); slightly soluble in ethanol (95%); insoluble in most organic solvents

Stable when stored in a tightly sealed container in a cool, dry place. Aqueous solutions are stable in sealed containers but need a preservative for multi-dose use. The polymer degrades slowly at 100 °C and rapidly at about 200 °C, and is stable on exposure to light.

Undergoes reactions typical of compounds with secondary hydroxyl groups, such as esterification. It decomposes in strong acids and softens or dissolves in weak acids and alkalis. High concentrations of inorganic salts, especially sulfates and phosphates, precipitate it from solution, and borax or boric acid form gels with it.

Made by hydrolysis (alcoholysis) of poly(vinyl acetate), usually in methanol with a sodium hydroxide catalyst; the degree of hydrolysis and the molecular weight of the starting polymer determine the grade. Vinyl alcohol monomer itself is unstable, so the polymer cannot be made directly.

Generally regarded as non-toxic; it is poorly absorbed from the gastrointestinal tract and is non-irritant to the eye and skin at the concentrations used.

Observe normal precautions for the quantity handled. Eye protection and gloves are recommended; avoid generating dust.

Accepted in Europe as a food additive for coating food supplements (E1203) and evaluated by EFSA and JECFA. Included in the FDA Inactive Ingredient Database (ophthalmic, oral, topical and transdermal preparations) and in non-parenteral medicines licensed in Europe.

Polyvinyl acetate phthalate; polyvinyl alcohol–polyethylene glycol graft copolymer.

Partially hydrolysed grades dissolve in cold water and are better emulsion stabilisers, while fully hydrolysed grades need heating to about 80–90 °C to dissolve but give stronger, more water-resistant films. Disperse the powder in cold water with stirring before heating to avoid lumps.