The Clinical Effects of Urea

Urea use in dermatology has been shown to be beneficial for skin, by providing moisturisation, emollient, keratolytic, skin barrier enhancing, antipruritic and antibacterial properties. 

Urea is a low-molecular-weight organic molecule composed of a carbonyl group attached to two amine residues. It is produced mainly after hepatic digestion of proteins. Urea is a hygroscopic molecule (capable of absorbing water) present in the epidermis as a component of the natural moisturizing factor (NMF) and is essential for the adequate hydration and integrity of the stratum corneum. A reduction in the hygroscopic capacity of the skin can increase transepidermal water loss (TEWL), deregulate epidermal proliferation and inhibit skin desquamation, inducing hyperkeratosis and pruritus. (1) 

Urea is a topical emollient and moisturizing keratolytic and antipruritic agent. It plays a key role in keratinocyte gene regulation. In Asia, Africa and Europe, the therapeutic use of urine (urotherapy) has been documented for centuries. One of the first uses of urea in modern medicine was the topical treatment of wounds due to its proteolytic and antibacterial properties [2]. Currently, urea is widely used in dermatology. It is prescribed for the treatment of diverse dermatoses presenting with scaly and dry skin such as atopic dermatitis, ichthyosis, seborrheic dermatitis and psoriasis, among others [3]. Furthermore, urea can increase skin penetration and optimize the action of topical drugs [3]. Urea-containing formulations are available in diverse formulations and concentrations as found in our Elixir range.

Urea-based formulations are well tolerated. Urea-containing creams may present an unpleasant odour, caused by volatile amine, but it dissipates rapidly [4] and with the Elixir cream range offering fragrances of Baked Cinnamon, Fresh Coconut, and French Vanilla, unpleasant odour is not something you need to worry about. Mild skin irritation is occasionally observed and can be more frequent with use at higher concentration. This adverse effect is temporary and usually self-resolving [5].

 The mechanisms of action of urea in dermatology are as follows:

1. Increases moisturization of the stratum corneum
2. Improves skin's barrier function and antimicrobial defence
3. Regulates epidermal proliferation
4. Keratolytic action
5. Increases drug penetration (including our premium ingredients which boast vitamins and minerals)

Topical Formulations Containing Urea

Urea can be easily incorporated into dermatological preparations because it is highly water soluble. There are multiple vehicles and formulations (creams, lotions, emulsions, ointments, gels, shampoos and nail lacquers, among others) and concentrations of urea available in over-the-counter products and prescription medications, which allows great versatility in its application. Diverse factors must be considered before choosing the most adequate product: the disorder to be treated, severity, area of the body involved (and its extension) and cosmetic acceptability [6]. In general, compounds with low urea concentration (2%–10%) are ideal for moisturizing and optimizing the skin’s barrier function [7]. Medium concentration (10%–30%) are ideal for moisturizers and keratolytics [8]. High concentrations (≥ 30%) are ideal for keratolytics and for debriding necrotic tissue [4].

The following table explains urea concentrations and uses in more detail:

Main Indications for urea in Dermatology

1. Maintaining healthy skin
2. Atopic dermatitis
3. Xerosis
4. Ichthyosis
5. Psoriasis
6. Hyperkeratosis and/ or Palmoplantar Keratodermas
7. Nail disorders
8. Tinea Pedis

Conclusions

Urea plays a fundamental role in regulating keratinocyte proliferation, the skin's barrier function and antimicrobial defence. Urea-based formulations are well tolerated and one of the most commonly prescribed moisturizers and keratolytic agents for dermatologic patients. Urea-containing formulations can maintain healthy skin and treat a wide range of skin disorders such as AD, xerosis, psoriasis, ichthyosis and seborrheic dermatitis, among many others, and to improve penetration of topical drugs into the skin and nails.

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