Urea (yoo-ree-a) (also known as carbamide, carbonyl diamide) is a topical preparation useful for treating a number of skin conditions that need a rehydration of the skin. Urea is an amide that has two amine groups which are joined by a carbonyl functional group. The body uses urea many processes, the most important being for nitrogen excretion. Urea is formed in the liver from ammonia that is produced by the deamination of amino acids, being the principal end product of protein catabolism. It is also commonly used in farming as a fertilizer for a source of nitrogen.
Urea is on the World Health Organization’s List of Essential Medicines.
Naturally, urea is an organic compound, but topical preparations of urea are synthesized from inorganic precursors in a process first discovered in 1828 by Friedrich Wöhler.
Mechanism of action of topical preparations:
Urea has different effects at different concentrations:
~40%: can dissolve the intercellular matrix of the nail plate (may be used for nonsurgical debridement of nails).
>20%: starts to become a keratolytic to cause a breakdown of proteins in the skin, so the dry skin can flake off
<20%: acts as a humectant to help the skin retain moisture and reduce water loss.
Urea also has anti-pruittic affects.
Indications:
In dry skin there is a significant reduction of urea in the epidermis.
Psoriasis, xerosis (dry and rough skin), onychomycosis (40%), ichthyosis, eczema, keratoderma, heel fissures (cracked heels)
Contraindications:
Hypersensitivity to urea or ingredients in the preparation.
Adverse effects:
The topical preparations have next to no adverse effects, except occasional local irritation (maybe a burning sensation or stinging sensation) – self limited and clears with the cessation of use.
The agricultural form of urea in fertilizer may cause a dermatitis from prolonged contact.
Interactions:
None are known.
Precautions:
There are no studies in pregnant women, but animal studies have shown no harm to the fetus
It is not known if urea is excreted in human milk.
Brand names: Walker’s, Umecta, Utopic, Kerafoam, Gordons, Decubal, Carmol, Keralac, and others
Chemical formula: CO(NH2)2
Availability: Over-the-counter
Advice to Patients:
Avoid contact with the eyes
Do not use on broken or bleeding skin
Wash hands after use
Packaging label for a preparation of urea
External Links:
Treatment of distal subungual onychomycosis with a topical preparation of urea
Should you use the 15% or 25% Walker’s Urea Foot Cream
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