Functional Category
Antimicrobial preservative.
Applications in Pharmaceutical Formulation
Imidurea is a broad-spectrum antimicrobial preservative used in cosmetics and topical pharmaceutical formulations; typical concentrations used are 0.03–0.5% w/w. It is effective between pH 3–9 and is reported to have synergistic effects when used with parabens;
Description
Imidurea is a white, free-flowing odorless powder.
Stability and Storage Conditions
Imidurea is hygroscopic and should be stored in a well-closed container in a cool, dry place.
Incompatibilities
Imidurea is incompatible with strong oxidants. It is compatible with other preservatives including sorbic acid and quaternary ammonium compounds.(5) It is also compatible with other pharmaceutical and cosmetic excipients including proteins, nonionic surfactants, and lecithin.
Safety
Imidurea is widely used in cosmetics and topical pharmaceutical formulations, and is generally regarded as a nontoxic and nonirritant material.(5) However, there have been some reports of contact dermatitis associated with imidurea, although these are relatively few considering its widespread use in cosmetics.(7–12) Although imidurea releases formaldehyde, it does not appear to be associated with cross-sensitization with formaldehyde or other formaldehyde-releasing compounds. LD50 (mouse, oral): 7.2 g/kg(13,14) LD50 (rabbit, skin): > 8 g/kg LD50 (rat, oral): 11.3 g/kg