Alessandra Pelosi

Hydration vs. skin permeability to nicotinates in man

Background/aims: Prolonged skin occlusion increases stratum corneum water content and often increases skin permeability and irritant dermatitis. As skin wetness from wearing diapers is considered an important factor favouring the onset of diaper dermatitis, optimal diapering might decrease skin hyperhydration and dermatitis. Our aim is to define the quantitative relationship between nicotinate ester (a model penetrant) skin permeability and hydration, as measured by water evaporation rate (WER), decay curves (at individual time points) and WER‐area under the curve (WER‐AUC); and also to determine the level of skin hydration and skin permeability to nicotinates following a diapering simulation.

Strontium nitrate suppresses chemically-induced sensory irritation in humans

Skin care products are complex formulations that may cause sensory irritation symptoms, characterized by stinging, burning, and itching. Substances capable of counteracting sensory irritation are of great practical interest. Strontium salts have been demonstrated to inhibit sensory irritation and inflammation when applied topically. In this double‐blind study, we evaluated the efficacy of strontium nitrate in reducing chemically‐induced skin sensory irritation in 8 subjects. In a random order, 20% strontium nitrate in 70% glycolic acid (pH=0.6) (mixture) was applied to the volar aspect of the forearm and a positive control (70% glycolic acid, pH=0.6) to the contralateral forearm. The irritation sensation was evaluated each min for the first 20 min after topical application using a scale from 0–4. The duration of the irritation sensation in min was also recorded. Strontium nitrate mixed with glycolic acid, in comparison with glycolic acid alone, markedly (p<0.01) shortened the duration of the irritation sensation from 24.4±4.1 (mean±SEM) min to 8.9±3.7 (mean±SEM) min, and significantly (p<0.05) reduced the mean magnitude of the irritation sensation at all time points (overall). The study demonstrated that strontium nitrate potently suppresses the sensation of chemically‐induced irritation.

A bioengineering study on the efficacy of a skin protectant lotion in preventing SLS‐induced dermatitis

Background/aims: This study evaluated the efficacy of a dimethicone skin protectant lotion against sodium lauryl sulfate (SLS)‐induced irritant contact dermatitis (ICD) by clinical visual grading and bioengineering techniques in 12 healthy humans.

Antipruritic and thermal sensation effects of hydrocortisone creams in human skin.

Few studies evaluate the effect of topical corticosteroids on thermal sensation and in alleviation of itch produced by intradermal injection of histamine. We evaluated the antipruritic effect of hydrocortisone (1% and 2.5%) on histamine-induced itch and sensory effects by measuring itch magnitude, itch duration and thermal thresholds using a computerized thermal sensory analyzer (TSA). This was a double-blind, random, comparative, controlled, single-dose and single-center study. Itch was experimentally induced in both forearms by intracutaneous injection of histamine in 18 subjects. Hydrocortisone 1%, 2.5% and placebo were applied to test sites on both forearms. The thermal threshold for warmth sensation, cold sensation, cold and heat pain was measured with the TSA. Itch magnitude was measured each minute after histamine injection for 10 min with a visual analogue scale (VAS). Itch duration was also recorded. In comparison to placebo, 2.5% hydrocortisone significantly (p = 0.03) reduced itch duration from 12.6 ± 11.0 min (mean ± SD) to 8.6 ± 8.2 min (the reducing rate was 32%) as well as itch magnitude (at minutes 3, 6, 7 and overall). Placebo, 1% and 2.5% hydrocortisone significantly altered (p <0.05) the cold sensation threshold. No treatment altered cold or heat pain thresholds. These data suggest that topical application of 2.5% hydrocortisone may be significantly beneficial for the treatment of histamine-induced itch. The correlation between thermal measurements and antipruritic effects warrants further study.

Strontium nitrate decreased histamine-induced itch magnitude and duration in man.

Background: Previous studies have demonstrated that strontium salts have a potent and broad ability to suppress sensory irritation. Objective: To ascertain the possible antipruritic effects of topical strontium salts, we conducted a double-blind randomized study to evaluate the effect of 20% strontium nitrate on itch magnitude (intensity) and duration. Methods: In 8 human subjects, strontium nitrate was applied to the volar forearm and vehicle control to the contralateral volar forearm for 30 min; both substances were reapplied for an additional 5 min. Itch was then experimentally induced by intradermal injection of histamine. Itch magnitude was rated each minute for the first 20 min using a visual analogue scale (VAS). Itch duration in minutes was also recorded. Results: Strontium nitrate, in comparison to its vehicle control, significantly shortened itch duration from 28.1 ± 5.4 min (mean ± SEM) to 18.5 ± 4.2 min (p < 0.01) and reduced itch magnitude at time points 12–20 min and overall (p < 0.05). Conclusion: Strontium nitrate may act as a topical antipruritic agent in reducing histamine-mediated itch.