Ethylparaben

• BPEthyl Hydroxybenzoate
• JPEthyl Parahydroxybenzoate
• Ph. Eur.Ethyl Parahydroxybenzoate
• USP–NFEthylparaben

Ethyl p-hydroxybenzoate; ethyl 4-hydroxybenzoate; ethylis parahydroxybenzoas; Nipagin A; Solbrol A; E214

Ethyl 4-hydroxybenzoate · [120-47-8]

UNII 14255EXE39 · PubChem CID 8434

C9H10O3 · 166.17

Antimicrobial preservative

Typical concentrations: — · Dosage forms: Liquid, Semi-solid

An antimicrobial preservative used in oral and topical pharmaceutical products, cosmetics and foods, effective over a wide pH range (about 4–8) and more active against yeasts and moulds than against bacteria. It is commonly used in combination with other parabens (methyl-, propyl- or butylparaben) to broaden the spectrum, at concentrations similar to or somewhat lower than those used for methylparaben, generally in the range of about 0.02–0.2%. In the EU, cosmetics may contain up to 0.4% of a single paraben (as acid) and 0.8% of paraben mixtures.

Colourless crystals or a white, odourless or almost odourless, crystalline powder.

Melting point

115–118 °C

Solubility

very slightly soluble in water; freely soluble in acetone, ethanol, ether and methanol

pKa

about 8.2

Effective pH range

about 4–8; activity falls at higher pH as the phenolate forms

Aqueous solutions at pH 3–6 are stable and can be autoclaved with little decomposition; at pH 8 or above hydrolysis is rapid. Store in a well-closed container in a cool, dry place.

Antimicrobial activity is markedly reduced by nonionic surfactants such as polysorbate 80, through micellar binding. Parabens can be absorbed by some plastics and adsorbed by magnesium trisilicate and aluminium silicate, are discoloured by iron and are hydrolysed by weak alkalis and strong acids.

Prepared by esterification of p-hydroxybenzoic acid with ethanol in the presence of an acid catalyst, followed by purification.

Parabens are rapidly absorbed, metabolised to p-hydroxybenzoic acid and excreted, and are of low systemic toxicity. Hypersensitivity reactions, mostly delayed contact dermatitis after topical use, are the main concern. Parabens have weak oestrogenic activity that increases with chain length; EFSA has set a group ADI for methyl- and ethylparaben and their sodium salts.

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

Accepted as a food additive in Europe (E214) and evaluated by JECFA. Included in the FDA Inactive Ingredient Database (oral and topical preparations) and in non-parenteral medicines licensed in Europe.

Butylparaben; methylparaben; propylparaben; sodium ethylparaben (E215).

Because of its limited water solubility, ethylparaben is usually dissolved in hot water, ethanol or propylene glycol before being added. The sodium salt is more water-soluble but raises the pH of unbuffered preparations.