Imidurea

• USP–NFImidurea

Abiol; Biopure 100; Germall 115; imidazolidinyl urea; Imidurea NF

N,N''-Methylenebis{N'-[3-(hydroxymethyl)-2,5-dioxo-4-imidazolidinyl]urea} · [39236-46-9]

UNII M629807ATL · PubChem CID 38258

C11H16N8O8 · 388.29

Antimicrobial preservative

Typical concentrations: 0.03–0.5% · Dosage forms: Semi-solid

An antimicrobial preservative used in topical pharmaceutical products and, much more widely, in cosmetics and toiletries, typically at 0.03–0.5% w/w. It is more active against bacteria than against yeasts and moulds, so it is usually combined with parabens or other antifungal preservatives, with which it acts synergistically.

A white, free-flowing, odourless or almost odourless, hygroscopic powder with a faint characteristic taste. It is a formaldehyde-releasing condensation product of allantoin and formaldehyde.

Solubility

very soluble in water; soluble in glycerin; sparingly soluble in propylene glycol; practically insoluble in most oils and in ethanol

Effective pH range

broad, about pH 3–9

pH

≈ 6.0–7.5 (1% w/v aqueous solution)

Hygroscopic. Store in a well-closed container in a cool, dry place.

Compatible with most cosmetic and topical ingredients, including non-ionic surfactants and proteins, which inactivate many other preservatives. As a formaldehyde donor, it may react with amines and other nucleophilic components.

Prepared by the condensation of allantoin with formaldehyde.

Of low systemic toxicity, but it can cause allergic contact dermatitis, partly through the release of formaldehyde; patients sensitised to formaldehyde may react to products containing it.

Observe normal precautions for the quantity handled; eye protection, gloves and a dust mask are recommended.

Included in the FDA Inactive Ingredient Database (topical preparations). In the EU it is permitted as a preservative in cosmetic products at up to 0.6%, and products containing formaldehyde releasers carry a warning when the released formaldehyde exceeds the set threshold.

Diazolidinyl urea; DMDM hydantoin; parabens; quaternium-15.

Because its antifungal activity is weak, imidurea alone rarely protects a formulation adequately; preservative efficacy testing should be carried out on the final product. The use of formaldehyde releasers is declining in favour of other preservative systems because of sensitisation concerns.