Optimising the use of urea in dermatology

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Advances in the use of topical imiquimod to treat dermatologic disorders

Imiquimod (IQ) is an immune-response modifying agent, first approved by FDA for the topical treatment of external genital and perianal warts in 1997. It induces, through stimulation of Toll-like receptors (TLRs) localized on the surface of antigen-presenting cells, synthesis and release of several endogenous pro-inflammatory cytokines such as interferon-α (IFN-α), tumor necrosis factor-α (TNF-α) and interleukins (IL) 6 and 12, which in turn stimulate both the innate and acquired immune pathways, resulting in upregulation of natural antiviral and antitumor activity. IQ 5% cream has been used for the treatment of a wide variety of dermatologic conditions in which the immune system is thought to play a role in regression of the disease. In some disorders, such as genital and perianal warts, actinic keratoses, basal cell carcinomas, Bowen’s disease and molluscum contagiosum, relative safety and efficacy are supported by randomized controlled trials of IQ. However, it is common for patients to experience local skin reactions, which can range from mild to severe in intensity, but usually resolve 1–2 weeks after interrupting treatment. Additional randomized trials are encouraged to assess safety and efficacy of IQ in the treatment of an even wider range of cutaneous disorders

Multiple reactive keratoacanthomas in a patient with hypertrophic lichen planus treated with cyclosporine: successful treatment with acitretin.

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All-Optical Method to Assess Stromal Concentration of Riboflavin in Conventional and Accelerated UV-A Irradiation of the Human Cornea.

PURPOSE. We investigated the concentration of riboflavin in human donor corneas during corneal cross-linking using two-photon optical microscopy and spectrophotometry. METHODS. Eight corneal tissues were de-epithelialized and soaked with 20% dextran-enriched 0.1% riboflavin solution for 30 minutes. After stromal soaking, three tissues were irradiated using a 3 mW/cm(2) UV-A device for 30 minutes and three tissues irradiated using a 10 mW/cm2 device for 9 minutes. Two additional tissues were used as positive controls. A Ti:sapphire laser at 810 nm was used to perform two-photon emission fluorescence (TPEF) and second harmonic generation axial scanning measurements in all specimens before and after stromal soaking and after UV-A irradiation. In addition, spectrophotometry was used to collect the absorbance spectra of each tissue at the same time intervals. Analysis of the absorbance spectra and TPEF signals provided measures of the concentration depth profile of riboflavin in corneal stroma. RESULTS. After stromal soaking, the average peak concentration of riboflavin (0.020% +-0.001%) was found between a stromal depth of 100 and 250 lm; the concentration of riboflavin was almost constant up to 320 6 53 lm depth, then decreased toward the endothelium, though riboflavin was still enriched in the posterior stroma (0.016%% 6 0.001%). After conventional and accelerated UV-A irradiation, the concentration of riboflavin decreased uniformly 87% 6 2% and 67% 6 3% (P < 0.001), respectively. CONCLUSIONS. The combined use of two-photon optical microscopy and spectrophotometry provides relevant information for investigating the concentration of riboflavin in corneal stroma. The method can assist with the assessment of novel riboflavin formulations and different UV-A irradiation protocols

History of urea as a dermatological agent in clinical practice.

Urea, also known as carbamide, is a polar, hygroscopic molecule produced by the human body that was first discovered in urine in 1773 by the French chemist Hilaire Rouelle and was artificially synthesised from inorganic precursors in 1828 by the German chemist Friedrich Wöhler. The importance of urea in dermatology is twofold: it primarily has a physiological key role for the maintenance of skin hydration, and it secondarily has been used for more than a century in different topical preparation and concentration in various skin conditions. One of the first uses of urea was the topical treatment of wounds because of its antibacterial and proteolytic properties. Since the second part of the 20th century, urea became one of the most common moisturisers and keratolytic agents, useful for the treatment of xerosis, atopic dermatitis, ichthyosis and psoriasis

Clinical evidences of urea at low concentration

Urea is a hygroscopic molecule that, because of its moisturising properties, is topically used for the treatment of skin dryness at concentrations ranging from 2% to 12% in different formulations. Based on existing literature, low-concentration urea-containing products are effective in the treatment and/or prevention of xerosis in some skin disorders such as ichthyosis, atopic dermatitis and psoriasis, or unrelated to specific skin diseases. Generally, urea formulations at low concentration are well-tolerated and suited for the treatment of large skin areas, once or twice daily, even for a long period of time. At low concentrations stinging and burning sensation is rare and transient, whit no reported sensitisation despite its widespread use

Clinical evidences of urea at medium concentration.

Urea-based topical compounds at medium concentrations (15%-30%) represent useful dermatological agents for their humectant and keratolytic effects by enhancing stratum corneum hydration and by loosening epidermal keratin, respectively. The aim of this paper is to review the clinical evidences of the use of 15%-30% urea as single topical agent. Although limited evidence supports the use of these concentrations of urea in skin disorders characterised by xerosis and hyperkeratosis, in clinical practice they are largely used especially in xerosis of limited skin areas, in which the side effects are tolerable, or hyperkeratosis involving large or more sensitive (eg, face, genital region, etc) areas, in which higher concentration may be irritant. In addition, urea at medium concentrations is used in combination with other substances including topical antifungals as penetration enhancer

Double-ended Pseudocomedones in Hidradenitis Suppurativa: Clinical, Dermoscopic, and Histopatho­logical Correlation

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