Walter Wigger-Alberti

Efficacy of a barrier cream and its vehicle as protective measures against occupational irritant contact dermatitis

The actual advantage of barrier creams over bland emollients for skin protection is still hotly debated. In a randomized, double‐blinded study, a newly‐introduced barrier cream and its moisturizing vehicle were compared regarding their skin compatibility, efficacy and resulting acceptance. Thus, 2 panels of 25 hospital nurses with mild signs of skin irritation were asked to use 1 of the test products provided (verum or vehicle) over a period of 4 weeks. Effects of both types of preparations were studied weekly by clinical examination and the instrumental assessment of bioengineering parameters. Results showed no significant differences between barrier cream and vehicle. In both groups, clinical skin status improved and stratum corneum hydration increased significantly during the study period. Both preparations were tolerated and accepted well, thus showing both skin protection and skin care. These results contribute to the debate as to whether a strict distinction between “skin care” and “skin protection” products is justified. The vehicle alone is capable of positively influencing skin status. Emphasis must be laid on regular, frequent, and correct application of a product for it to be effective.

Direct and Non-Direct Measurement Techniques for Analysis of Skin Surface Topography

Estimation of skin smoothness is of ever-increasing interest especially in the field of cosmetic research. There are some established methods for assessing skin smoothness, e.g. optical and mechanical profilometry, but the presentation of recently developed new methods reflects the demand for alternatives which are more precise and practical. For fundamental research on ultrastructure of the stratum corneum surface scanning electron microscopy is a suitable method. A direct method is the surface evaluation of living skin, which is based on an optical system in a CCD camera measuring four parameters of roughness, scaling, smoothing and wrinkling. A similar but non-direct method is optical profilometry using skin replicas. Laser profilometry produces a variety of data which can be analysed using complex mathematical functions. A promising new method is transparency profilometry (skin visiometer) using a very thin skin print which allows parallel light to pass through and is analysed immediately after production. The different methods can be used for characterization of the skin microrelief in dermatoses or for dynamic measurements of time-dependent changes in skin surface topography after application of cosmetic or medical products.

Multicentre study for the development of an in vivo model to evaluate the influence of topical formulations on irritation

Although skin protective products to prevent irritant skin reactions are in wide use, neither standardized test models to prove differences in efficacy exist, nor has the quality or the reproducibility of results been evaluated in a multicentre approach. This should be mandatory when developing or testing skin care products. Therefore, we have designed a multicentre study in an approach to find a standardized test procedure for the evaluation of skin protective products. In this irritation study, a repeated short‐time occlusive irritation test (ROIT) with a standardized protocol has been evaluated in 2 phases (12 days and 5 days protocol) in 4 (n=20) respectively 6 (n=33) skilled centres. The skin reaction was induced by 2 irritants (0.5% aq. SLS and toluene, 2× a day for 30 min). Its modification by 3 different cream bases with different hydrophilicity was analyzed. The irritation was monitored by bioengineering methods (TEWL measurement, colorimetry) and by clinical scoring. The evaluation showed that significant results could already be achieved with the 5‐day protocol. Furthermore, in spite of the expected inter‐centre variations due to heterogeneity of the individual threshold of irritation, interpretation of clinical score, and inter‐instrumental variability, the ranking of the vehicles regarding reduction of the irritant reaction was consistent in all centres.

Percutaneous penetration of topically applied melatonin in a cream and an alcoholic solution.

In a clinical study, the skin penetration properties of melatonin 0.01% in a cream and 0.01 and 0.03% in a solution were investigated by evaluation of the serum melatonin levels over a 24-hour time course in 15 healthy volunteers. Blood samples for melatonin measurements were taken at 9.00 a.m. before applying the test preparations and 1, 4, 8 and 24 h after application. The measurements were carried out by radioimmunoassay for melatonin. In 15 volunteers, the serum levels of melatonin before application of the topical preparations were between 0.6 and 15.9 pg/ml. After application of the 0.01% melatonin cream, there was a steady increase starting from 9.00 a.m. up to a mean serum value of 9.0 pg/ml at 9.00 a.m. the next day. The solution of 0.01% melatonin also showed an increase, starting from 5.00 p.m., up to a mean melatonin level of 12.7 pg/ml 24 h after application. The solution containing 0.03% melatonin resulted in elevated melatonin levels 1 and 8 h after application. The values were 18.1 and 19.0 pg/ml. The cumulative melatonin values for each preparation were 7.1, 8.6 and 15.7 pg/ml, respectively. This study shows that the strongly lipophilic substance melatonin is able to penetrate through the skin and leads to dose- and galenic-dependent melatonin levels in the blood. No increase of melatonin above the physiological range was observed.

Emollients in a propanol-based hand rub can significantly decrease irritant contact dermatitis

The objective of this study is to determine the effect of emollients in a propanol‐based hand rub on skin dryness and erythema. In this prospective, randomized, controlled, double‐blind trial, 35 subjects participated; of them approximately half were atopic (modified Erlanger atopy score ≥8). 2 propanol‐based formulations were tested in a repeated open application test, 1 contained a mixture of emollients (0.81%, w/w). 2 aliquots of 0.7u2003ml of each formulation were applied twice per day over 2 weeks to the cubital fossa of each subject after random assignment of the preparations. Treatment areas were assessed before each application and 3 days postfinal application by visual inspection for erythema and dryness according to a standard scale. The sum score over all assessment time‐points served as primary parameter. The mean sum score for erythema and dryness was significantly lower for the hand rub with emollients (0.8u2003±u20032.4) in comparison with that for the hand rub without emollients (1.5u2003±u20033.5; Pu2003=u20030.022; Wilcoxon signed rank test). A comparison of the atopic and non‐atopic subjects revealed no significant difference for any of the products (Pu2003>u20030.05; Mann–Whitney U‐test). It is concluded that the addition of emollients to a propanol‐based hand rub can significantly decrease irritant contact dermatitis under frequent‐use conditions.

The tandem repeated irritation test: A new method to assess prevention of irritant combination damage to the skin

The effect of a protective cream was tested in a new tandem repeated irritation test with tandem application of 0.5% sodium lauryl sulphate (SLS) and undiluted toluene. The irritants were applied twice daily for 30 min to the ventral forearms of 20 volunteers. Irritant cutaneous reactions were quantified by a visual score, transepidermal water loss, chromametry and skin capacitance. Concurrent application of SLS/toluene induced stronger reactions than those caused by twice daily application of each irritant on its own. A protective effect of the protective cream was obtained against all treatment combinations and was significant for SLS/SLS (p < or = 0.01) and SLS/ toluene (p < or = 0.05). Our results indicate that the tandem repetitive irritation test has great potential in the evaluation of skin care products to prevent irritant contact dermatitis.

Assessment of 'dry skin': current bioengineering methods and test designs.

Dry skin is a frequent problem in dermatology and a sign of dysfunction of the epidermis, especially of the stratum corneum as the morphological equivalent of the skin barrier. It may occur as an individual disposition or as the leading symptom of atopic dermatitis or ichthyosis. Besides the visual examination of the skin, various bioengineering methods have been developed to assess the different pathological and adaptive changes in the skin. In addition to the assessment of skin humidity, barrier function and desquamation, the quantification of skin surface topography and the mechanical properties of skin are suitable methods to characterize a dry skin condition. For clinical assessment of moisturizing products and emollients the parameters of investigation have to be defined and integrated in an adapted study design depending on the composition and content of the active agent in the test product. Newly developed cosmetic products have to be investigated for safety and efficacy. Modern bioengineering methods are suitable to fulfill these challenges.

Natural vegetable fats in the prevention of irritant contact dermatitis

Chronic irritant contact dermatitis (ICD) is one of the most pressing problems in occupational medicine and is common in the food processing industry. To date, protective creams that fulfil the special requirements in the foodstuffs industry have not been available. Therefore, we studied the efficacy of pre‐exposure application of natural vegetable fats in the prevention of experimentally induced ICD. A panel of 20 healthy volunteers was tested with a repetitive irritation test using sodium lauryl sulfate (SLS) as a standard irritant in a randomized study. Application sites were assessed clinically and by the use of bioengineering techniques (evaporimetry, chromametry, and corneometry). Rape seed and palm fats showed significant protective potential. Gas‐chromatographic analysis revealed differences in the fatty acid composition of the vegetable. Higher content of linoleic acid and lower content of oleic acid was associated with beneficial effects. Our results are a new approach in the prevention of ICD and towards the development of new protective preparations for workplaces in the foodstuffs industry.

Melatonin in der Dermatologie Experimentelle und klinische Aspekte

ZusammenfassungMelatonin (N-Acetyl-5-Methoxytryptamin) ist ein unter dem Einflußβ-adrenerger Rezeptoren von der Glandula pinealis produziertes und sezerniertes Hormon mit vielfältigem Wirkungsspektrum. Die Ausschüttung des Hormons folgt einem zirkadianen Rhythmus mit niedrigen, gleichmäßigen Spiegeln tagsüber und einem abendlichen Ansteigen und nächtlichen Peak zwischen 2.00 und 4.00 Uhr. Melatonin beeinflußt den saisonalen Biorhythmus, den Schlaf-Wach-Rhythmus, den Alterungsprozeß und moduliert immunbiologische Abwehrfunktionen. Zusätzlich besitzt Melatonin unabhängig von einem Rezeptorsystem durch seine starken lipophilen Eigenschaften die Fähigkeit, frei durch Zellmembranen zu diffundieren und im extra- wie intrazellulären Raum als Radikalfänger zu wirken. Die Affinität zu dem stark schädigenden Hydroxylradikal ist besonders groß. In der Dermatologie ergeben sich für Melatonin Perspektiven bei einigen Hauterkrankungen wie zum Beispiel dem atopischen Ekzem, der Psoriasis und dem malignen Melanom. Der Einfluß von Melatonin auf das Haarwachstum ist ein weiterer Aspekt. In topischer Anwendung hat Melatonin eine suppressive Wirkung auf die Ausbildung eines UV-Erythems. Über die Penetrationseigenschaften durch die Haut und die orale Verfügbarkeit liegen einige Erkenntnisse vor, die durch weitere Untersuchungen der Pharmakokinetik und Pharmakodynamik ergänzt werden können.SummaryMelatonin (N-acetyl-5-methoxytryptamine) is a hormone with multiple functions in humans, produced by the pineal gland and stimulated by β-adrenergic receptors. Serum melatonin levels exhibit a circadian rhythm with low levels during the day, rise in the evening and maximum levels at night between 2 and 4 a.m.. Melatonin participates in the regulation of several physiological processes such as seasonal biological rhythm, daily sleep induction, aging and modulation of immunobiological defence reactions. Furthermore, melatonin has a highly lipophilic molecular structure facilitating penetration of cell membranes and serving as an extra- and intracellular free radical scavenger. Melatonin seems to quench mainly hydroxyl radicals, the most damaging of all free radicals. Melatonin may play a role in the etiology and treatment of several dermatoses e.g. atopic eczema, psoriasis and malignant melanoma. The influence of melatonin on hair growth is another aspect. Topical application of melatonin inhibits the development of UV-erythema. Penetration through skin after topical application and oral bioavailability auxit further investigations on the pharmacokinetic and pharmacodynamic actions of melatonin.

Transepidermal Water Loss Dynamics of Human Vulvar and Thigh Skin

Refinement in procedures to assess skin surface water loss (SSWL) dynamics of the vulvar skin on a large sample of subjects (60) is described and compared to another semi-occluded skin site, the inner thigh. Vulvar SSWL significantly decreased over a 30-min period from 46.2 ± 2.6 (SE) to 24.7 ± 1.6 g m–2 h (p < 0.001). The inner thigh, another semi-occluded region, showed no similar pattern for SSWL (6.2 ± 0.3 to 6.6 ± 0.5 g m–2 h), and the values were significantly less than those for vulvar skin. There was no significant effect of age, body mass index or atopic status on vulvar SSWL.